A Guide for establishing primary AC-DC transfer
standard using ET2001 ADS system
(Tentative Version 2.01, 12/Apr./2007)
Nano-Electronics Research Institute / AIST, Japan
Preliminary Version 1.03b
About This Manual
This manual, "A Guide for establishing primary AC-DC transfer standard using ET2001 ADS system",
provides detailed technical information about the operation of type-ET2001 AC-DC Standard
system (hereafter referred to as “ADS” system), and its application for the evaluation of thermal
converters to establish a primary AC-DC transfer standard.
Contents of the other manuals are as follows:
“Quick-Start Manual for ET2001 ADS system”
This manual provides technical information for the use of ET2001 ADS system, including
comprehensive guidance for installation and initial setting-up of the equipment.
"Technical Reference for ET2001 ADS system Hardware"
This manual provides detailed technical information about hardware of the ET2001 ADS
system, including the interfacing commands and circuit descriptions.
"Technical Reference for ET2001 Thermal Converters"
This manual provides detailed technical information about the special TVCs, LF-TVC, HFTVC, and MF-TVC, to be combined with the ET2001 ADS system.
The organization of the manual is to first provide a simple overview of AC-DC transfer standard
using the ET2001 ADS system. This is followed by examples for setting up the equipment and
program in Chapters 2 - 3. Subsequent chapters provide information on the operation of FRDCDC, AC-LF, and AC-DC difference measurements (Chapters 4 - 6), followed by examples on the
evaluation of TC modules in Chapter 7. Supplementary information is given in Chapter 8.
chapter 1
Concepts of
ADS system
chapter 8
Supplementary
Information
Introductory guide
for AC-DC standard
chapter 4
chapter 2
Configure
System
FRDC-DC Measurement
chapter 5
AC-LF Measurement
chapter 3
Set-up
Software
FAQs, Credits
Contact Address
chapter 6
AC-DC Measurement
chapter 7
Evaluation of
Thermal Converter
Guide for evaluation of
AC-DC difference of TCs
Preliminary Version 1.03b
Important Notes
(PS&USB Module)
CAUTION! --- Check correct voltage setting for the AC line voltage before applying the ac
power to the PS&USB module.
(FRDC Module)
CAUTION! --- Output current of more than 30 mA may results in the permanent damage
for analog switches in the output circuit.
NOTE --- Output voltage lower than 1V may not have sufficient output stability.
(DSS Module)
CAUTION! --- Output current of more than 50 mA may results in the permanent damage in
the output buffer circuit.
NOTE --- Output voltage lower than 1V may not have sufficient output stability.
NOTE --- Output current of more than 30 mA may cause instability in the output and
increase in the distortion of the waveform.
(TC/AMP Module)
CAUTION! --- Incorrect setting of the [Nominal Input] in [TVC specification] may result in
the overloading of the thermal converter element.
CAUTION! --- Incorrect setting of the [Input resistance] in [TVC specification] may result
in the overloading of the FRDC and/or DSS output circuit.
NOTE --- When connecting a TVC to AMP module, the Input-Lo/Guard of the AMP
module should be connected to Output-Lo of FRDC/DSS module via
Output-Lo/Chassis of the TVC.
NOTE --- All the TC/AMP modules must have corresponding specification files
stored in the "Etrace\TCspecs" folder.
Preliminary Version 1.03b
List of Abbreviations
AC-AC [AC to AC (difference)]: Relative AC-DC difference with respect to fixed frequency.
AC-DC [AC to DC (difference)]: Error in comparing rms AC quantity with DC quantity.
AC-LF [AC to Low Frequency AC (difference)]: LF characteristic in AC-AC difference.
ADC [Analog to Digital Converter]: Converts output EMF of TC element to digital quantity.
AMP [Amplifier (module)]: TC module without dedicated TC element inside the chassis.
CPDC [Chopped DC (mode)]: Quasi steady-state DC waveform with periodical off-times.
DVM [Digital Voltmeter]: Replaced by AMP module in ET2001 ADS system.
ADS [(ET2001) AC-DC Standard (system)]: The equipment described in this manual.
DDS [Direct Digital Synthesis (chip)]: A semiconductor chip for generation of sine-wave.
DSS [Digital Sine-wave Synthesizer (circuit)]: A circuit (module) for generation of sine-wave.
FRDC [Fast-Reversed DC]: Quasi-rectangular waveform with equal rms power in AC and DC.
HF-TVC [High-Frequency Thermal Voltage Converter]: A TVC for high-frequency reference.
GPIB [General-Purpose Interface Bus]: Interface bus commonly used in measuring instruments.
LF-TVC [Low-Frequency Thermal Voltage Converter]: A TVC for low-frequency reference.
MDFR [Modified FRDC (mode)]: Modified FRDC waveform with periodical off-times.
MDR [Miniature Delta Ribbon (cable)]: A standard cable used in ET2001 ADS system.
MES [Measurement]: A thermal AC-DC transfer standard to be calibrated (UUT).
PS [Power Supply (circuit)]: Power supply circuit in USB&PS module.
REF [Reference]: Reference standard by which UUT standard is calibrated.
TC [Thermal Converter]: Thermal Converter to be used in AC-DC comparison.
TC [Thermal Converter (module)]: Combination of a TC element and a ADC circuit.
TVC [Thermal Voltage Converter]: Thermal Converter for AC voltage standard.
USB [Universal Serial Bus]: Serial Interface Bus used in ET2001 ADS system
USB&PS [USB and Power Supply (module)]: Power-supply module with USB interface.
UUT [Unit Under Test]: A thermal AC-DC transfer standard to be calibrated (MES).
Preliminary Version 1.03b
Table of Contents
1. Introduction................................................................................................................. 8
1.1. Background .......................................................................................................... 8
1.2. AC-DC Transfer Standard..................................................................................... 8
1.2.1. AC-DC Difference ..................................................................................... 8
1.2.2. Thermal Converter ..................................................................................... 9
1.3. Determination of Frequency Characteristics........................................................ 11
1.3.1. DC Characteristics ................................................................................... 11
1.3.2. Low-Frequency Characteristics ................................................................ 12
1.3.3. High-Frequency Characteristics ............................................................... 13
1.4. Principles of Measurements ................................................................................ 13
1.4.1. FRDC-DC Difference Measurement ........................................................ 13
1.4.2. ACLF-AC Difference Measurement......................................................... 16
1.4.3. AC-DC Difference Measurement ............................................................. 17
2. Set-up ET2001 ADS System ...................................................................................... 19
2.1. System Overview................................................................................................ 19
2.2. FRDC System..................................................................................................... 20
2.2.1. Configuration........................................................................................... 20
2.2.2. Measurement Sequence............................................................................ 21
2.3. AC-LF System.................................................................................................... 21
2.3.1. Configuration........................................................................................... 22
2.3.2. Measurement Procedure ........................................................................... 22
2.4. AC-DC System................................................................................................... 23
2.4.1. Configuration........................................................................................... 23
2.4.2. Measurement Procedure ........................................................................... 24
3. Set-up ET2001 ADS Software ................................................................................... 26
3.1. Software Components......................................................................................... 26
3.2. Manual Operation ............................................................................................... 27
3.2.1. Initial Set-up Procedure............................................................................ 27
3.2.2. Manual Operation .................................................................................... 29
3.3. Setting Parameter................................................................................................ 32
3.3.1. Register Reference Point .......................................................................... 32
3.3.2. Register Measurement Procedure ............................................................. 33
3.3.3. Register Measurement Parameter ............................................................. 35
3.3.4. Specify File Name to Save Results........................................................... 36
3.3.5. Register Measurement Options................................................................. 37
3.3.6. Specify Email Address to Send Data. ....................................................... 37
3.4. Start/Stop Measurement...................................................................................... 38
4. FRDC-DC Difference Measurement......................................................................... 41
4.1. Executing Measurement...................................................................................... 41
4.1.1. Measurement Procedure ........................................................................... 41
4.1.2. Data Format ............................................................................................. 43
Preliminary Version 1.03b
4.2. Curve-fitting ....................................................................................................... 44
4.3. Evaluation of Uncertainty ................................................................................... 44
4.3.1. Type-A Uncertainties ............................................................................... 45
4.3.2. Type-B Uncertainties ............................................................................... 46
4.3.3. Uncertainties in Sensitivity Coefficient .................................................... 48
4.3.4. Combined Uncertainty ............................................................................. 49
5. AC-LF Measurement ................................................................................................ 51
5.1. Executing Measurement...................................................................................... 51
5.1.1. Measurement Procedure ........................................................................... 51
5.1.2. Data Format ............................................................................................. 52
5.2. Evaluation of Uncertainty ................................................................................... 53
5.2.1. Type-A Uncertainties ............................................................................... 53
5.2.2. Type-B Uncertainties ............................................................................... 55
5.2.3. Uncertainties in Sensitivity Coefficient .................................................... 55
5.2.4. Combined Uncertainty ............................................................................. 57
6. AC-DC Difference Measurement.............................................................................. 58
6.1. Executing Measurement...................................................................................... 58
6.1.1. Measurement Procedure ........................................................................... 58
6.1.2. Data Format ............................................................................................. 60
6.2. Evaluation of Uncertainty ................................................................................... 61
6.2.1. Type-A Uncertainties ............................................................................... 61
6.2.2. Type-B Uncertainties ............................................................................... 62
6.2.3. Uncertainties in Sensitivity Coefficient .................................................... 63
6.2.4. Combined Uncertainty ............................................................................. 65
7. Evaluation and Calibration of TC modules.............................................................. 66
7.1. General Scheme.................................................................................................. 66
7.2. Evaluation of a Reference Thermal Converter..................................................... 66
7.2.1. Method of Evaluation............................................................................... 66
7.2.2. DC Characteristics ................................................................................... 67
7.2.3. Low Frequency Characteristics ................................................................ 68
7.2.4. High Frequency Characteristics................................................................ 68
7.2.5. Over-all Characteristic ............................................................................. 69
7.2.6. Evaluation of Uncertainty ........................................................................ 70
7.3. Calibration of a Thermal Converter..................................................................... 71
7.3.1. Comparison of AC-DC transfer difference ............................................... 71
7.3.2. Evaluation of Uncertainty ........................................................................ 73
7.3.3. Remote Calibration .................................................................................. 74
8. Supplementary Information...................................................................................... 75
8.1. FACs .................................................................................................................. 75
8.2. Trouble Shooting ................................................................................................ 75
8.3. Acknowledgements............................................................................................. 75
8.4. Contact Address.................................................................................................. 75
Preliminary Version 1.03b
Appendix
Appendix-A Data Examples ..................................................................................179
Preliminary Version 1.03b
1. Introduction
1.1. Background
DC voltage standards precise to 10-9 are achievable with Josephson junction devices. High
precision for AC voltages, even to 10-7 are much more difficult to measure, so that the method to
set an AC standard most commonly used is through the "transfer" or comparison with a precision
DC standard. This is achieved by comparing the RMS power of the AC voltage with that of the
standard DC using a thermal converter. AC voltage standards in the frequency range between 10
Hz and 1 MHz can thus be derived. However, because every electrical system is subject to noises
from many sources, with many dependent on the frequency, predetermined corrections must be
added to the measurements to compensate for these and to calibrate the equipment under test.
Especially troublesome are non-negligible heating or cooling during the DC input mode. These
Thomson and Peltier thermoelectric effects give rise to frequency-independent AC-DC differences
at a 10-6 level [1]. Because of the difficulties in avoiding or evaluating the thermoelectric effects in
a thermal converter, only a limited number of national metrology institutes have been able to
establish independent primary standards of AC-DC transfer. Since 2001, the AIST in Japan [3]
uses the Fast-Reversed DC (FRDC) method to evaluate the frequency independent AC-DC
difference in the transfer standard.
FDRC was developed in the 1990's, aiming at the experimental determination of the
thermoelectric effects in thermal converters [2]. The FRDC method is based on the assumption
that, if the frequency of the polarity reversal in a rectangular FRDC waveform is much faster than
the thermoelectric time constant, the thermoelectric effects do not affect the temperature
distribution.
This document describes a second-generation FRDC instrument, ET2001 AC-DC Standard (ADS)
System, developed at AIST in cooperation with Sunjem Co. Ltd, Japan. The new instrument
includes not only the FRDC source, but also a complete miniature AC-DC comparator system,
consisting of a DSS module, TC/AMP modules, and HF-TVC. The system may be used to
establish an independent primary AC-DC transfer standard in calibration laboratories.
1.2. AC-DC Transfer Standard
1.2.1. AC-DC Difference
The ac voltage is defined by the root-mean square (rms) value of the sinusoidal waveform:
VAC (rms) ≡
1
T
∫
T
0
2
{V (t)} dt
€
-8-
(1.1)
Preliminary Version 1.03b
In accordance with this definition, it is possible to compare an ac voltage with a dc voltage by
alternately applying them to the same heater in a thermal converter (TC) and measuring the
temperature rise with a thermocouple. When dc and ac voltages that result in equal power output are
applied to the input of an ideal thermal converter, the resultant EMFs are the same. In the case of an
actual TC, however, the output EMFs are influenced by the effect of non-joule heating and the
frequency dependent characteristics of the heater circuit. The AC-DC transfer difference is
conveniently defined by the following equation.
δ AC − DC ≡
VAC − VDC
VDC
(1.2)
E AC = E DC
The quantities EDC and EAC represent the output EMFs of the thermocouple when the dc voltage
VDC and the ac voltage VAC, respectively, are applied to a thermal converter.
Steady-State DC
AC(Sine wave)
Output
Input
VDC
EDC
VAC (t)
EAC ( f )
Thermal
Converter
Fig. 1.1 Thermal converter for AC-DC transfer Standard
1.2.2. Thermal Converter
The most accurate AC-DC transfer standards are realized by the use of "thermal converters".
Single-Junction Thermal Converters (SJTCs) were developed in the 1950s. The structure of a
typical SJTC element is shown in Fig. 1.2. A thin filament-heater and a thermocouple are enclosed
in an evacuated glass bulb. The thermocouple junction is in thermal contact with the heater at the
midpoint of the heater, but is electrically insulated from it by a bead of glass or ceramic.
Multijunction Thermal Converters (MJTCs) were developed in the 1970s-1980s. The MJTCs are
designed to suppress the Thomson and Peltier effects. These are the main cause of the AC-DC
transfer difference around 1 kHz. The structure of type-JSTC04 thermal converter element,
developed at AIST in cooperation with Nikkohm Co., is illustrated in Fig. 1.3. The thermopile
(thermocouples connected in series) is formed on a thin polyimide membrane supported by an
alumina (Al2O3) frame. The heater is formed on an AlN (aluminum nitride) chip mounted on the
polyimide membrane. The thermal converters are capable of comparing the joule heating between
ac and dc modes at 0.1 ppm level, and are widely employed as the primary standard in most
national standard laboratories.
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Preliminary Version 1.03b
Heater
Bead
Support Lead
Glass Bulb
Thermocouple
Fig. 1.2 Structure of Single-Junction Thermal Converter
Heater
(NiCr)
Thermocouple
(Bi/Sb)
Output-Hi
Polyimide
Film
Input-Hi
AlN
Chip
Alumina
Frame
Input-Lo
Output-Lo
Fig. 1.3 Structure of JSTC04 Multi-Junction Thermal Converter
There are three main causes of the AC-DC transfer difference:
(1) Thermoelectric effect (dc offset): When the dc current is passed through the heater of a
thermal converter, non-joule heating/cooling takes place along the heater due to thermoelectric
effects such as the Thomson or Peltier effect. In the case of SJTC with standard construction,
an AC-DC difference of a few ppm is observed due to the thermoelectric effects.
(2) High-frequency characteristic: In the frequency range above 10 kHz, the skin effect of the
conductor and the stray inductance and capacitance in the input circuit become significant.
When a standard-design SJTC-element is combined with a current-limiting metal-film resistor
of 1kΩ, the effect to the AC-DC transfer difference is of the order of 0.1 ppm, 1 ppm, and 100
ppm at the frequency of 10 kHz, 100 kHz, and 1 MHz, respectively.
(3) Low-frequency characteristics: The thermal time constant of a standard-design SJTC-element
is about 1 s. At frequencies below 100 Hz, double-frequency thermal ripple is created due to
insufficient thermal inertia. In the case of a standard SJTC, the effect to the AC-DC difference
is of the order of 0.1 ppm and 10 ppm at 100 Hz and 10 Hz, respectively.
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Preliminary Version 1.03b
The AC-DC transfer difference of a thermal converter over the 100 Hz to 1 MHzfrequency range
is given in equation 1.3. The three components are as follows:
LF: low frequency component
HF: high frequency component
TE: thermoelectric effects
(1.3)
δ AC − DC ≅ δ LF ( f ) + δ HF ( f ) + δ TE
The typical frequency characteristic of a thermal converter is illustrated in the figure. Frequency
characteristic of a thermal converter can be evaluated using special thermal converters (HF-TVC
and LF-TVC), as described in subsections 1.3.2 and 1.3.3. The thermoelectric effects, which occur
at the dc-mode, give the frequency-independent offset in the AC-DC difference. Since both the
low-frequency characteristic and the high-frequency characteristic reduce below 0.1 ppm in the
frequency range between 100 Hz and 10 kHz, the AC-DC difference in this range is predominately
a DC offset due to the thermal effects and is not frequency dependent.
δAC-DC
Thermal
Ripple
Stray L,C
δTE
0
10 kHz
100 Hz
DC Offset
f
Fig. 1.4 Frequency characteristic of a thermal converter
1.3. Determination of Frequency Characteristics
1.3.1. DC Characteristics
The major source of the frequency-independent AC-DC difference is the second-order Thomson
effect. The typical temperature distribution along the heater due to Joule-heating is shown in Fig.
1.5(a). When the Thomson effect is present, the electric current influences the heat flow and
modifies the temperature gradient along the heater. The change in temperature distribution due to
the Thomson effect is shown in Fig. 1.5(b). The Thomson effect can result in a temperature
distribution as large as 0.1 K. However, most of the effects are canceled to the first-order by
reversing the polarity of the current and taking the mean. The temperature gradient due to the
second-order Thomson effect is of the order of a few mK, as shown in Fig. 1.5(c), and contributes
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Preliminary Version 1.03b
to the AC-DC difference at the ppm level. The AC-DC difference due to the second-order Thomson
effect can be evaluated using the formula by Widdis:
δac −dc
2
1 σ θ0
=−
12 ρk
(1.4)
The symbols σ, θ0, ρ, and κ represent the Thomson coefficients, mid-point temperature-rise,
electric resistivity, and the thermal conductivity of the heater. In the case of standard SJTCs, the
thermal transfer difference is of the order of a few parts in 10-6. The thermoelectric effects in
thermal converters can be evaluated by the "fast-reversed dc" method.
ΔT
Joule
Component
(a)
≅100K
x
1st-order
Thomson
Effect
DC-
ΔT
≅0.1K
x
2nd-order
Thomson
Effect
DC+
(b)
ΔT
≅1mK
x
(c)
Fig. 1.5 Temperature distribution along heater
1.3.2. Low-Frequency Characteristics
When sinusoidal voltage of frequency f is applied to a TVC (thermal voltage converter), joule
heating varies with double-frequency, 2f. If the frequency is sufficiently high, i.e., if the thermal
time constant τ is much longer than the period of the double-frequency heating (τ>>1/f), the
variation of temperature becomes negligible due to the thermal inertia of the heater. At
frequencyies below 100 Hz, thermal inertia of the heater becomes insufficient to suppress the
double-frequency thermal ripple. The thermal ripple causes the AC-DC difference of a TVC due
to the imperfections in the SJTC elements:
(a) Non-linearity of input-output characteristic of TVC.
(b) Frequency dependence of the heater-resistance.
(c) Imperfect averaging of the voltage ripple in EMF output.
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Preliminary Version 1.03b
In the case (c), the effect to the AC-DC difference may be reduced by use of a low-pass filter or by
setting the integration time of a DVM to the multiple of the input frequency. While in cases (a)
and (b), the effects are based on the thermal properties of the SJTC elements, and the contribution
to the AC-DC difference has to be evaluated.
The low-frequency performance of a thermal converter may be evaluated by two methods using the
ET2001 ADS system, i.e., (1) Impedance-matching method and (2) AC-LF measurement
(synthesized-waveform method).
In the case of the Impedance-matching method, AC-DC difference of a TVC is compared against
another TVC of the same type using a special comparison circuit, such that one TVC is operated at
a much smaller power level than the other. In the case of the AC-LF measurement, a synthesized
waveform source (DSS module) is used as a reference standard, and the change in the output EMF
from the TVC is measured by a DVM (AMP module). These methods are described in detail in a
separate technical reference "TC manual".
1.3.3. High-Frequency Characteristics
Operating at above 10 kHz, the frequency characteristic of the TVC-input circuit due to the skin
effect, dielectric loss, and the stray inductance and capacitance becomes non-negligible compared
with thermoelectric effects. Beyond 100 kHz, the frequency characteristic contributes more than 1
ppm and becomes the dominant term in the AC-DC transfer difference.
Since the impedance of the input circuit determines the frequency characteristic of a TVC, it is quite
important do define the reference plane of the input circuit from which the AC-DC difference is
defined. Usually, the reference plane is taken at the center of a TEE connector directly connected to
the input of a TC or TC module. The primary standard in the high-frequency characteristic of ACDC difference is realized by a specially designed TVC (HF-TVC), which has a special construction
so that its high-frequency characteristic is calculable from its structure and dimensions. The design
and the performance of the HF-TVC is described in detail in a separate technical reference "TC
manual".
1.4. Principles of Measurements
1.4.1. FRDC-DC Difference Measurement
Until the late 1990's, the ac-dc transfer standard in Japan had an uncertainty of 10 ppm. This
precision was not good enough to calibrate new instrumentation. Application of the "Fast-Reversed
DC" (FRDC) method, developed at PTB (Physikalisch-Technische Bundesanstalt), has allowed
ten-fold improvement in the uncertainty of the national standard. The purpose of the method is to
evaluate the thermoelectric transfer difference experimentally, as illustrated in Fig. 1.6. For
simplicity, only the Thomson effect along the heater is shown in the figure. When dc current passes
through a thermal converter, the temperature distribution is modified due to the Thomson effect as
shown in Fig. 1.6(a). When the current is reversed, the polarity of the Thomson effect is also
reversed, resulting in a different temperature distribution along heater as shown in Fig. 1.6(b). The
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Preliminary Version 1.03b
characteristic time constants of the change in the temperature distribution due to the Thomson and
Peltier effects are determined by the structure and material of the heater, hereafter called
"thermoelectric time constants". In the case of FRDC mode, if the reversal of the current is slow
enough compared with the thermoelectric time constants, the same temperature distribution along
the heater is obtained as that for the steady-state dc, as shown in Fig. 1.6(c). Hence the average
output EMF of thermal converter in the slow-reversing mode is equal to the mean output EMF for
DC+ and DC- modes, and the FRDC-DC difference becomes zero. On the other hand, if the
reversal of the current is fast enough, thermoelectric effects do not have enough time to develop
during one current direction, and the influence of thermoelectric effects is reduced to zero, as
shown in Fig. 1.6(d). In this case, the FRDC-DC difference equals to the thermoelectric effect in dc
modes.
DC[+]
DC[-]
Slow Switching
Fast Switching
Thomson
component
Joule
component
x
x
(a)
(b)
(c)
(d)
Fig. 1.6 Thermoelectric effects in thermal converters with the FRDC waveform.
In the FRDC-DC difference measurement, rectangular-waveform are synthesized by switching
between a positive dc source (DC+) and a negative dc source (DC-) as illustrated in Fig. 1.7. The
switching is performed using high-speed analog switches. If the switching is performed in a perfect
way, a high-precision rectangular ac waveform is obtained whose rms power is equal to the mean
of the two dc sources. The rectangular waveform synthesized in this way is called the FastReversed DC (FRDC) waveform, and the circuit for producing the FRDC waveform is called the
FRDC source. Following the definition of the AC-DC difference of a thermal converter given by
(1.5), an "FRDC-DC difference" δFRDC-DC is defined as follows:
δ FRDC − DC ≡
VFRDC − VDC
VDC
(1.5)
E FRDC =E DC
Here, EFRDC represents the EMF for the FRDC waveform, and EDC represents the mean EMF for
the DC+ and DC- waveform. A modified waveform shown in Fig. 1.8 is used in the actual FRDC
sources. Since the same number of positive edges and negative edges are included in DC and
FRDC waveform, the effect from switching transients and high frequency components are canceled
between the DC and FRDC modes.
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Preliminary Version 1.03b
Thermal
Converter
DC+
nV
Detector
DCFig. 1.7. FRDC-DC difference measurement circuit.
DC(-)
FRDC
DC(+)
Fig. 1.8 Modified DC and FRDC waveforms.
In this method, the Nono-Voltmeter measures the output EMF voltages from the TVC. If the
difference between the voltages VFRDC and VDC is small, the input-output characteristic can be
approximated to be linear in the low voltage range. In this case, the following approximation is
possible:
VFRDC ≅ VDC + [ EFRDC − EDC ] k
Where, k =
ΔE
.
ΔV
(1.6)
€
Here, ΔE represents the change in the EMF output from the TVC when a small change in the input
voltage ΔV is applied. Substituting (1.6) to (1.5), the FRDC-DC difference δFRDC-DC is determined
€
by the following equation:
δFRDC−DC ≅ −
EFRDC − EDC
nEDC
Where, n =
€
(ΔE / E )
(ΔV /V )
(1.7)
The 'normalized index n is of the order of 2 for the TVCs with square-output characteristics. In the
case of modified waveform, the quantities
EFRDC and EDC represent the average EMFs for the two
€
MDFR modes and for the two CPDC modes respectively, as defined by,
EFRDC ≡
EMDFR(1) + EMDFR(2 )
,
2
E DC ≡
ECPDC+ + ECPDC −
2
- 15 -
(1.8)
Preliminary Version 1.03b
1.4.2. ACLF-AC Difference Measurement
As discussed in section 1.3.2, the low-frequency performance of a thermal converter may be
evaluated by two methods using the ET2001 ADS system, i.e., (1) Impedance-matching method
and (2) the AC-LF measurement (synthesized-waveform method) which is described in this section.
In this measurement, a synthesized waveform source (DSS module) is used as a reference standard.
The change in the output EMF from the TVC is measured by a DVM (AMP module).
The "ACLF-AC difference" δACLF is defined using the following definition.
δ ACLF ≡
V ( f ) −V ( f0 )
V ( f0 )
E ( f )=E ( f
(1.9)
0)
Here, E(f) represents the EMF at the test frequency f, and E(f0) represents the EMF at the reference
frequency f0. €
The schematic diagram of the measurement circuit is shown in figure 1.9. In this method, the main
detector is the DVM (ADC in TC module) which measure the output EMF voltages from the TC
element.
AC
Thermal
Converter
nV
Detector
Fig. 1.9 AC-LF Measurement Circuit.
As in the case of the FRDC-DC difference measurement, if the difference between the voltages V(f)
and V(f0) is small, the input-output characteristic can be approximated to be linear in the small
voltage range. In this case, the following approximation is possible:
VAC ( f ) ≅ VAC ( f0 ) + [ E( f ) − E( f0 )] k
Where k =
ΔE
.
ΔV
(1.10)
€
Substituting (1.10) to (1.9), the ACLF difference δACLF is determined by the following equation:
δ ACLF ≅ −
€
E( f ) − E( f0 )
nE( f0 )
€
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Preliminary Version 1.03b
Where, n =
(ΔE / E )
(ΔV /V )
(1.11)
Normalized index "n" is of the order of 2 for the TVCs with square-output characteristics.
€
1.4.3. AC-DC Difference Measurement
The purpose of the AC-DC difference (comparison) measurement is to determine the relative
difference in the AC-DC difference between two TVCs, usually specified as TC(X) and TC(S). The
ET2001 ADS system performs the AC-DC difference measurement based on the dual-channel
method. The schematic diagram of the dual channel method is shown in Fig. 1.10. In this method,
the two nV-detectors measure the output EMF voltages of the two TVCs separately.
TC(X)
nV
Detector
DC+
DC-
TEE
nV
Detector
AC
TC(S)
Fig. 1.10 AC-DC difference measurement circuit.
The input-output characteristics of the two TVCs are shown in Fig. 1.11. The EMF output of a
TVC is approximately proportional to the square of the input voltage. The output-quantity XDC and
SDC represent the EMF outputs from TVC(X) and TVC(S) for the dc input voltage VDC. Similarly,
the output-quantity XAC and SAC represent the EMF outputs for the ac input voltage VAC. The inputquantity VX and VS represent the ac input voltages which produce the same EMF voltage (XDC, SDC)
as in the case of applying the dc input voltage VDC.
Using the definition of the AC-DC difference of a TVC given in (1.2), the relative AC-DC
difference between TVC(X) and TVC(S) is deduced as
δX − δS ≡
VX − VS
VDC
.
(1.12)
X AC = X DC
S AC = SDC
If the difference between the dc input voltage VDC and ac input voltage VAC is small, the inputoutput characteristic of the two TVCs may be approximated to be linear in the small voltage range.
In this case, the following approximation is possible:
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VX ≅ VAC + ( X DC − X AC ) k X

VS ≅ VAC + (SDC − SAC ) kS
Where k X =
ΔX
ΔS
.
, kS =
ΔV
ΔV
(1.13)
Here, ΔX and ΔS represent the change in the EMF output from TVC(X) and TVC(S) when a small
change in the input voltage ΔV is applied. Substituting (1.13) to (1.12), the relative AC-DC
difference δ X − δ S is determined by the following equation:
δX − δS ≅
SAC − SDC XAC − X DC
−
nS SDC
n X X DC
Where n X =
(ΔX / X DC )
,
(ΔV / VDC )
nS =
( ΔS / SDC )
(ΔV / VDC )
(1.14)
The normalized indices nX and nS are of the order of 2 for the TVCs with square-output
characteristics. Some of the semiconductor-based AC-DC transfer standards, like Fluke 792A or
Datron 4920, have linear output characteristics, resulting in normalized indexes close to unity.
Output
(X)
EAC
(X)
EDC
XDC
(S)
EAC
XAC
(S)
EDC
SDC
SAC
VAC
VS
VX
VDC
Fig. 1.11. Input-Output Characteristic
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Preliminary Version 1.03b
2. Set-up ET2001 ADS System
2.1. System Overview
The new AC-DC transfer standard system was developed at AIST in cooperation with SunJEM Co.
The system consists of four main components, i.e., FRDC module, Digital Sine-wave Synthesizer
(DSS) module, Thermal Converter (TC) or Amplifier (AMP) module, and Power Supply/Interface
(PS/IF) module. The appearance of the FRDC, DSS and TC modules are shown in figure 2.1. The
complete set of modules can be packed into a B4-file size attaché case, and the whole system can be
transported to the calibration site if required.
A. FRDC Module
FRDC module is a rectangular-waveform voltage source to be used in FRDC-DC difference
measurement. It produces accurate FRDC and DC waveforms with amplitudes from 1 V to 10 V
and switching frequencies between 0.1 Hz and 10 kHz. The design of the FRDC circuit is based on
the "source A/B switching" scheme [2], in order to establish the equality of rms values between the
FRDC and DC waveforms.
B. DSS Module
DSS module generates highly stable sinusoidal ac and dc outputs to be used in AC-DC difference
measurements. The module is based on a direct-digital-synthesizer (DDS) device, and generates
frequencies between 10 Hz and 1 MHz at rms voltages from 1 V to 10 V. In the evaluation of lowfrequency characteristics of thermal converters, the DSS module is used as a reference in ac voltage
standard.
C. TC Module
TC module is a digital-output thermal converter. The module consists of a thermal converter
element, a precision A/D converter as a nV detector, a D/A converter for offset compensation, and
an optically isolated digital control circuit. The AMP module is almost identical to the TC module,
except that it does not contain a dedicated thermal converter element, and the type-N input
connector is replaced with a low-thermal DC input connector to be combined with an external
thermal converter such as HF-TVC.
D. USB&PS Module
USB&PS module provides isolated DC power sources to the main modules. Switching regulator
circuits are avoided to minimize the effect of high-frequency interference to the sensitive nano-volt
detection circuit. The module also provides an optically isolated USB-to-serial interface circuit
between a PC controller and the FRDC, DSS, and TC modules.
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Preliminary Version 1.03b
Fig. 2.1 ET2001 ADS system
2.2. FRDC System
FRDC-DC difference measurement is performed using a FRDC module and one TC module to be
evaluated. The TC module may be replaced by a combination of conventional thermal converter
and an AMP module.
The standard procedure for the measurement is as follows:
(1) Configuration --- Connection of the three modules (FRDC, TC/AMP, USB&PS) and setting-up
the control program.
(2) Setting Parameter --- Registering various measurement conditions and measurement options
step-by-step.
(3) Execute Measurement --- Performing a fully automated FRDC-DC difference measurement.
(4) Data Analysis --- Determination of a thermoelectric transfer difference of the thermal converter.
2.2.1. Configuration
CASE 1 --- Measurement with a TC module
(1) Connect an AC Power cable and a USB cable to USB&PS module. Then turn on the power
switch.
(2) Check green light in front panel, and connect a 26-pin MDR cable to “FRDC/DSS” port.
(3) Connect the other end of the 26-pin MDR cable to a FRDC module.
(4) Connect a 20-pin MDR cable to “TC#1(X)” port of USB&PS module.
(5) Connect the other end of the 20-pin MDR cable to the TC (or AMP) module.
(6) Connect the N-R input connectors of the FRDC module and the TC (AMP) module with an
NP-NP adopter or with a NP-NP cable no longer than 50 cm.
CASE 2 --- Measurement with a thermal converter and an AMP module.
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Preliminary Version 1.03b
Same as CASE 1 except that the TC module is replaced by a combination of a thermal converter
and an AMP unit. The Input-Lo and the Output-Lo of the thermal converter must be connected
to the Input-Lo of the AMP module.
TC module
FRDC module
Fig. 2.2 FRDC measurement
2.2.2. Measurement Sequence
The FRDC-DC difference of a TC module is measured using a measurement sequence [*+-//-+*],
where the symbols represent:
[*]: Modified FRDC (A+/B-): MDFR[1] mode
[+]: Chopped dc (A+/B+): CPDC[+] mode
[-]: Chopped dc (A-/B-): CPDC[-] mode
[/]: Modified FRDC (A-/B+): MDFR[2] mode
At each FRDC output mode, the output EMF from the TC element is measured by the internal AD
converter, and the digital data are transferred to the controller (PC) via the PS/IF module. The
readings are averaged for specified number of reading, and the FRDC-DC difference is calculated
using the formula (2.7) described in section 2.3.1. The complete FRDC measurement sequence is
described in section 4.1
2.3. AC-LF System
The ACLF system is for an AC-AC difference measurement at low-frequency range (<100Hz), to
evaluate low-frequency characteristic of a TC module. The ACLF measurement uses fixedsampling-per-period output-mode of the DSS module, and low-frequency characteristic of a TC
module is evaluated using the DSS module as a reference standard. The TC module may be
replaced by a combination of conventional thermal converter and an AMP module.
The standard procedure for the measurement is as follows:
(1) Configuration --- Connection of the three modules (DSS, TC/AMP, USB&PS) and setting-up
the control program.
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(2) Setting Parameter --- Registering various measurement conditions and measurement options
step-by-step.
(3) Execute Measurement --- Performing a fully automated ACLF measurement.
(4) Data Analysis --- Determination of a thermoelectric transfer difference of the thermal converter.
2.3.1. Configuration
CASE 1 --- Measurement with a TC module
TC module
DSS module
Fig. 2.3 ACLF measurement
(1) Connect an AC Power cable and a USB cable to USB&PS module. Then turn-on the power
switch.
(2) Check green light in front panel, and connect a 26-pin MDR cable to “FRDC/DSS” port.
(3) Connect the other end of the 26-pin MDR cable to a DSS module.
(4) Connect a 20-pin MDR cable to “TC#1(X)” port of USB&PS module.
(5) Connect the other end of the 20-pin MDR cable to the TC (or AMP) module.
(6) Connect the N-R input connectors of the DSS module and the TC (AMP) module with an NPNP adopter or with a NP-NP cable no longer than 50 cm.
CASE 2 --- Measurement with a thermal converter and an AMP module.
Same as the configuration shown above except that the TC module is replaced by a combination
of a thermal converter and an AMP unit. The Input-Lo and the Output-Lo of the thermal
converter must be connected to the Input-Lo of the AMP module.
2.3.2. Measurement Procedure
Three-mode measurement sequences, [AC(ref) / AC(test) / AC(ref)], are used to measure the
difference in the EMF output with frequency, while eliminating the influence of linear drift in DSS
output and EMF output voltage.
AC(test): Sinusoidal AC output at test frequency
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AC(ref): Sinusoidal AC output at reference frequency
To avoid the effects from transient response after mode-switching, controller waits for specified
period (normally 10s - 20 s) before integrating the reading from the TC/AMP module. The AC-AC
difference is calculated using the formula (2.11) described in section 2.3.2. The complete ACLF
measurement sequence is described in section 5.1
2.4. AC-DC System
The AC-DC system is for an AC-DC or AC-AC difference measurement using a DSS module at
fixed-sampling-per-period mode. This measurement determines relative difference between two TC
modules, TC(X) with respect to TC(S). The TC module(s) may be replaced by a combination of
conventional thermal converter(s) and AMP module(s).
The standard procedure for the measurement is as follows:
(1) Configuration --- Connection of the four modules (DSS, TC/AMP(X), TC/AMP(S), USB&PS)
and setting-up the control program.
(2) Setting Parameter --- Registering various measurement conditions and measurement options
step-by-step.
(3) Execute Measurement --- Performing a fully automated AC-DC difference comparison
measurement.
(4) Data Analysis --- Determination of a thermoelectric transfer difference of the thermal converter.
In the comparison of the AC-DC difference in the higher frequency range (>10 kHz), frequency
characteristic of a TVC including the connecting circuit between the TVCs becomes significant.
Hence, it is widely accepted to define the branch-point of a TEE connector, which connects the
TVCs and the AC/DC source, as the 'reference-plane' from which the frequency characteristic of a
TVC is evaluated. In the case of standard TVC using type-N receptacle (N-R) as the input
connector, the center of N-type TEE connector (N-TA-RRR) is taken as the reference plane.
2.4.1. Configuration
CASE 1 --- Measurement using TEE connector
(1) Connect an AC Power cable and a USB cable to USB&PS module. Then turn-on the power
switch.
(2) Check green light in front panel, and connect a 26-pin MDR cable to “FRDC/DSS” port.
(3) Connect the other end of the 26-pin MDR cable to a DSS module.
(4) Connect a 20-pin MDR cable to “TC#1(X)” port of USB&PS module.
(5) Connect the other end of the 20-pin MDR cable to the TC (or AMP) module.
(6) Connect another 20-pin MDR cable to “TC#2(S)” port of USB&PS module. Also, connect the
other end of the 20-pin MDR cable to the TC (or AMP) module.
(7) Connect the N-R input connectors of the DSS module and the two TC modules (or TC) with an
NP-NP adopter or with a NP-NP cable no longer than 50 cm.
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Preliminary Version 1.03b
TC module(X)
TC module(S)
TEE
DSS module
Fig. 2.4 ACDC measurement
CASE 2 --- Measurement using a HF-TVC and a TC module.
TEE connector is replaced by a built-in TEE inside a HF-TVC. The output of the HF-TVC is
connected to AMP module.
AMP module
HF-TVC
TC module
DSS module
Fig. 2.5 ACDC measurement
2.4.2. Measurement Procedure
[1] AC-DC Difference measurement
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Preliminary Version 1.03b
A set of two four-mode standard measurement sequences, [AC/DC+/DC-/AC] and [AC/DC/DC+/AC] are used in turn to eliminate the influence of linear drift and to check the dependence on
the sequence in DC+ and DC-:
AC: Sinusoidal AC output at test frequency
DC+: Steady-state positive DC output.
DC-: Steady-state positive DC output.
[2] AC-AC Difference measurement]
As in the case of ACLF measurement, three-mode measurement sequences, [AC(ref)/AC(test)/
AC(ref)], is used to measure the difference in the EMF output with frequency.
In either measurements, controller waits for specified period (normally 10s - 20 s) before
integrating the reading from the TC/AMP module(s). The AC-DC or AC-AC difference is
calculated using the formula (2.14) described in section 2.4.2. The complete measurement
sequence for the AC-DC or AC-AC difference measurements are described in section 6.1
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Preliminary Version 1.03b
3. Set-up ET2001 ADS Software
3.1. Software Components
The package of ET2001 control software is composed from the following items.
(1) Main program ET01vXIII
---Executable basic program.
(2) "Defsetting" File
---Preset values for et2001 control program
(3) "ErrorLog" file
---Log file to report errors.
(4) "TCspecs" folder
---Folder in which information on the registered TC modules are recorded.
---IMPORTANT--- All TC/AMP modules must have corresponding data file in this folder.
(5) "Procedures" folder
---Folder in which measurement procedures are registered.
(6) "MesResults" folder
--- A default folder in which measurement data is to be recorded.
(7) "Tools" folder
---Folder which contains USB Interface driver (D10606) and utility program
(8) "Manual" folder
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Preliminary Version 1.03b
(9) "ET2001" package folder
Installer for ET2001 program.
3.2. Manual Operation
3.2.1. Initial Set-up Procedure
(1) Double click “ET01vX…” icon in the installed directory to start program.
(2) “Configuration Prompt Message” window will appear. (The color of the LED stays green,
showing that no power is applied to the MDR ports, and it is safe to connect or disconnect
modules.) Check the following condition:
(a) USB cable is connected.
(b) USB&PS module is Powered ON.
(c) All the modules are connected to the USB&PS module.
Check proper configuration for each specific measurements (FRDC, AC-LF, AC-DC, etc). Then
click “Proceed” button to apply power to the modules. (The color of the LED will turn to yellowish
green, showing that now it is NOT safe to connect or disconnect modules.)
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Preliminary Version 1.03b
(3) When AMP modules are connected to port-1, a message window will appear prompting the
input of description for the TVC connected to the AMP module. Check “OK” to proceed. (Not
necessary for TC module.)
(4) “[TC-X] Specification” window will appear. Chose appropriate description (or edit and save as
a new list.) Check “Select” to proceed. (Not necessary for TC module.)
To make a new entry, type in the information on the thermal converter to be measured. To protect
the TCs and/or FRDC/DSS modules from overloading, following information is required in the
specification list:
Nominal Input: Maximal input voltage to be applied to TC.
Nominal Output: Output EMF at the nominal input voltage.
Input Resistance: Current compliance is calculated from this.
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Preliminary Version 1.03b
Time Constant: Gives warning if measured value differs.
Output Curve: for calculating EMF output voltage.
(5) When AMP modules are connected to port-2, repeat the same procedure for “[TC-S]
Specification” window
(6) After a few seconds, a message window will appear notifying the completion of initial set-up
procedure. Check “OK” to proceed to manual control or setting measurement parameters. In the
case of an AC-DC difference measurement, the initially displayed windows are:
(b)
(c)
(a)
(d)
(e)
(f)
(a) Main window:
(b) DSS module control/display:
(c) TC-X module control/display:
(d) TC-X module control/display:
(e) Output EMF monitor:
(f) Temperature monitor:
3.2.2. Manual Operation
(a) Main window
Use “Manual Control” menu to control modules manually, or use “Measurement” menu or “SET”
button to proceed to the next stage.
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Preliminary Version 1.03b
(b-1) FRDC module control/display
This window is displayed when an FRDC module is connected to Port-1 (FRDC measurement).
This window shows (1) Serial Number of the FRDC module, (2) Output voltage, (3) Output
frequency, (4) Output modes, (5) EXEC/STBY condition, (6) Waveform parameter, and (7)
Adjustment parameters for the four sources A+/A-/B+/B-.
(b-2) DSS control/display
This window is displayed when a DSS module is connected to Port-1 (ACDC/ACAC measurement).
This window shows (1) Serial Number of the DSS module, (2) Output voltage, (3) Output
frequency, (4) Output modes (AC/DC/ACLF), (5) EXEC/STBY condition, (6) Buffer operation,
and (7) Adjustment parameters for the AC/DC+/DC- sources and offset in AC.
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Preliminary Version 1.03b
(c) TC modules control/display
These windows show (1) Serial Number of TC/AMP module, (2) DVM reading, (3) Temperature
monitor inside the TC/AMP module, (4) Gain/Offset setting, and (5) parameters describing the
TC/AMP modules connected to Port-2 and Port-3, respectively. Only one window is displayed for
FRDC and ACLF measurements.
(d) Output EMF monitor
This window displays the output trace from the TC/AMP module(s) during the integration period.
Green line represents reading from TCX, and yellow line represents one from TCS.
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Preliminary Version 1.03b
(e) Temperature monitor
This window displays the change in the temperature inside the TC/AMP module(s). It displays the
initial warm-up condition, and usually shows the temperature several degrees higher than the
ambient temperature after stabilization. Green line represents reading from TCX, and yellow line
represents one from TCS.
3.3. Setting Parameter
3.3.1. Register Reference Point
[Case 1 / FRDC measurement]
FRDC measurement has no reference point and this window is skipped automatically.
[Case 2 / ACLF measurement]
Reference Frequency for AC-LF
Set reference frequency (default 100 Hz) for an AC-AC(ref) difference measurement. Then select
resolution (number of sampling per period) to 1/512 (default) or 1/1024. Click “OK” button to
proceed.
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Preliminary Version 1.03b
[Case 3 / ACDC difference measurement]
Set reference to DC for an AC-DC difference measurement or to some reference frequency (default
1kHz) for an AC-AC(ref) difference measurement. Resolution of waveform (number of sampling)
is fixed to 1/32 micro sec.
3.3.2. Register Measurement Procedure
Use “Edit/Save” button to make a new procedure or modify an existing procedure. Use “Select”
button to proceed.
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Preliminary Version 1.03b
Measurement Procedure ---Editing Procedure
Use “Add/Delete/Register” buttons to edit an existing procedure.
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Preliminary Version 1.03b
The voltage level must be in the range between 1 V to 10.2 V, and should not exceed more than
120% of the nominal input voltage of TC. The allowable frequency range is from 10 Hz to 1 MHz
for AC-DC and AC-AC measurements and 5 Hz to 200 Hz for AC-LF measurement.
Use “NewFile/Save” buttons to either create a new file or overwrite the existing procedure, and use
“EXIT” button to exit this window and continue setting parameters.
3.3.3. Register Measurement Parameter
Start-up Wait: Waiting time for initial heat-up of thermal converter element. The first test point may
be used as a dummy measurement for additional start-up wait.
Wait for Trigger: Waiting time before accumulation of ADC reading is started, e.g., during the
mode change between (AC/DC+/DC-). Roughly set as time constants x10.
ADC Integration: Accumulation (integration) time for ADC reading, e.g., repetition number for one
Voltage/Frequency setting. Should be roughly equal to the “Wait for Trigger”.
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Preliminary Version 1.03b
Measurement/block: Repetition number for one Voltage/Frequency setting. Should be larger than 5
to calculate standard deviation accurately.
3.3.4. Specify File Name to Save Results.
Specify directly and name of the file to which the measurement data are stored.
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Preliminary Version 1.03b
Initial default directory is “C:\Program Files\Etrace\MesResults”. Any other directory may be
selected, and the new directory will be recorded as a new default in to the “DefSetting” file.
3.3.5. Register Measurement Options
Input Measurement Option
Recommended options are,
Drift Allowance : 10 ppm/min. (May not be sufficient for most accurate measurements)
Ending Option : Go to stand-by mode. (power-off modules, safer option)
Index Measurement Option : Always Measure Index. (for quick check use Skip-Measurement
option)
3.3.6. Specify Email Address to Send Data.
Set Email Report Option
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Preliminary Version 1.03b
After registering all the parameter or options, click “OK” to go back to the main menu. (The
measurement will NOT start automatically.)
3.4. Start/Stop Measurement
After registering all the parameter or options, the “SET” button will change to “GO” button, ready
for a fully automated FRDC-DC/ACLF-AC/AC-DC/AC-AC difference measurement. Hit the “GO”
button to start measurement. (The “GO” button will change to “STOP” button, which enables the
abortion of the measurement.)
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Preliminary Version 1.03b
[Automated Measurement]
Typical appearance of display (screen) during the automated FRDC-DC difference measurement is
shown below. The fourth parameter “RT” displayed on the bottom of the main widow shows the
approximate remaining time before the measurement will be completed.
[ End of measurement]
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Preliminary Version 1.03b
After finishing the measurement, the program go to the stand-by mode showing the “Configuration
Prompt Message” window, ready to restart another FRDC measurement or change configuration to
ACDC or ACLF measurements.
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Preliminary Version 1.03b
4. FRDC-DC Difference Measurement
4.1. Executing Measurement
4.1.1. Measurement Procedure
The measurement procedure of an FRDC-DC difference measurement is basically the same as that
for standard AC-DC difference measurements. Flow-chart of the measurement procedure is shown
in Fig 4.1.
Start
Initialize
Input
Parameters
Measurement
Block #1
Set Meas.
Parameters
Measure
Index "n"
FRDC [1] Mode
DC [+] Mode
Adjust Four
Sources (A±/B±)
DC [-] Mode
Measurement
Sequence #1
FRDC [2] Mode
Measurement
Block #n
FRDC [2]Mode
DC [+] Mode
Measurement
Sequence #m
DC [-] Mode
Measurement
Block #N
Ending
Procedure
Change
Mode
Wait for
Stabilization
DVM
Reading
FRDC [1] Mode
Measurement
Sequence #M
Calculate δ
Re-adjust
Sources
Store Data
to DISK
END
Fig. 4.1 flow-chart of FRDC-DC difference measurement program.
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Preliminary Version 1.03b
After registering all the parameters or options, as described in chapter 3, the program will go to
stand-by mode, ready for a fully automated FRDC-DC difference measurement. When "GO" button
is pressed, the program will apply voltage to the TC module, and waits for a specified period of
time (normally 10 minutes) to avoid the effects from initial warm-up drift. Then the program
repeats procedure (1) to (5) at each test points (Measurement Loops) as follows.
(1) Measurement of sensitivity index
The control program measures the normalized sensitivity index n at each test point. The normalized
sensitivity indices are measured by changing the input voltage by dV (normally 0.1%). Influence of
drift of the output voltage is removed by a measurement sequence [(V-dV ) / (V+dV ) / (V-dV)].
NOTE ----- After repeating the index-measurement 10 times, the program proceeds to the
next stage with warning message that the drift is too large.
(2) Adjustment of voltage level
The FRDC and CPDC waveforms are generated by combining four independent voltage sources
(A+, A-, B+, B-) inside FRDC module. The amplitudes of the outputs from the four sources are
automatically adjusted within 0.01% relative to each other. This process reduces AC components in
the power and prevents low frequency thermal ripple.
NOTE ---- After repeating the adjustment five times, the program proceeds to the next stage
with warning message that the adjustment is not sufficient.
(3) Measurement sequence
In the case of FRDC-DC difference measurement, the following eight-mode measurement sequence
is used to eliminate the influence of linear drift in FRDC output and EMF output voltage:
[FRDC/CPDC+/CPDC-/FRDC/FRDC/CPDC-/CPDC+/FRDC]
To avoid the effects from transient response after mode-switching, program waits for specified
period (normally 10 s) before reading the EMF from TVC. Then the readings of the DVM are
integrated for 10 s ~ 20 s and average values and standard deviations are calculated.
(4) Determination of FRDC-DC difference
The FRDC-DC difference is calculated using formula (2.7). The measurement sequences are
repeated for 10 times, and average value and standard deviation for the FRDC-DC difference is
obtained.
(5)Storing measurement data
After measurement sequence, measurement conditions and measurement data of each test point are
stored to hard disk of measurement controller. The recorded items are listed in the following subsection.
After measurements for all test points are executed, summary of measurement data are stored to the
hard disk of the system controller. Then instruments are reset to initial condition preparing for the
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exit from the measurement program. In the case of standard measurement condition, one
measurement loop takes about one hour. For a set of 16 standard test points from 0.1 Hz to 5kHz
repeated twice, whole measurement (33 points) takes approximately 32 hours.
4.1.2. Data Format
The results from the FRDC-DC difference measurement are stored into the specified data-file using
the same format as displayed in the [Data Recorded to File] window.
The data-file consists of the following records.
(1) Title "Data from FRDC-DC difference measurement."
(2) Revision Number of the control program
(3) Main header common to all measurement-blocks, including:
(3-1) Comment of the measurement,
(3-2) ID (serial) number of FRDC module,
(3-3) Name, ID (serial) number, and description of TC/AMP module,
(3-4) Input resistance of TC and fixed Dummy-resistance (1kohm),
(3-5) Off-time,
(3-6) Number of repetition for one measurement blocks,
(3-7) Waiting time before the ADC integration, and for initial warm-up time.
(3-8) Number of ADC sampling.
(4) Time constant of TC (measured).
(5) Data for one set of measurements, consisting of:
(5-1) Measurement block number,
(5-2) Date and Time of each measurement block,
(5-3) Output Level/Mode for each block,
(5-4) Switching Period/Frequency for each block,
(5-5) Result of TC Index measurement,
(5-6) Result of Source adjustments,
(5-7) Results of one measurement-sequence "∗+−//−+∗", consisting of:
(5-7-1) Measurement-sequence number,
(5-7-2) Time of each measurement-sequence,
(5-7-3) Temperature inside TC/AMP module,
(5-7-4) EMF outputs for each mode ("∗+−/"),
(5-7-5) Average standard deviation of EMF outputs in ppm,
(5-7-6) FRDC-DC difference for each sequence in ppm,
(5-8) Average FRDC-DC difference for each measurement-block
(5-9) Standard deviation of FRDC-DC difference in ppm.
(6) Summary of the measurement.
(7) Error/Warning message during the measurement.
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Preliminary Version 1.03b
4.2. Curve-fitting
Thermoelectric transfer difference δTC is the most important quantities to be evaluated by the
FRDC-DC difference measurement of a TC. Most of the MJTCs, including JSTC04 and JSTC05,
are successfully designed to reduce the thermoelectric transfer difference within the detection
sensitivity (<0.1ppm). Typical results from FRDC-DC difference measurement for SJTCs and
MJTCs are shown in Fig. 4.2.
6.0
SJTC S10-32
4.0
2.0
SJTC S12-57
MJTC N136
0.0
SJTC S6-8
MJTC PTB73
-2.0
-4.0
SJTC S10-45
MJTC GL32472
SJTC S10-28
-6.0
0.1
1
10
100
1000
1000
Switching Frequency (Hz)
Fig. 4.2 Typical results of FRDC-DC difference measurement.
In the case of SJTCs with measurable thermoelectric transfer difference, the time constants can be
evaluated by curve-fitting the data of δFRDC-DC to a formula that determines the frequencydependence of δFRDC-DC.
T 
 2τ 
δFRDC−DC = δTE  TE  tanh SW  .
 TSW 
 2τ TE 
(4.1)
A simple mathematical model of the thermoelectric effect in a thermal converter has been
introduced
in [7]. In this model, the thermoelectric effect was represented by an excess current
€
iTE=δTEi0 which responds exponentially with a time-constant τTE. Please refer to ref.[7] for more
detailed information.
4.3. Evaluation of Uncertainty
In this section, the uncertainty is estimated for the FRDC-DC difference measurement. The
sources of uncertainty are divided into two categories, namely, Type-A and Type-B. The type-A
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uncertainties can be evaluated from actual measurement as the standard deviation of the data, while
the type-B uncertainties have to be estimated using different methods depending on the nature of
the sources of uncertainty.
4.3.1. Type-A Uncertainties
The type-A uncertainty in the FRDC-DC difference measurement for a "test"-TC module (UUT)
is contributed from either uncertainty related to FRDC output ΔV or that to the output EMF voltage
ΔE from TC. Considering the square input-output characteristic of standard TVC, the uncertainty
components in ΔE contributes with factor one-half to the FRDC-DC difference:
dV 1 dE
,
=
V n E
(4.2)
The type-A uncertainty is composed of the following components:
€
(1) Stability/noise of FRDC module output
In the case of an FRDC module of the ET2001 ADS system, typical thermal drift is specified to be
<10 ppm/deg. Though linear drift in the output is compensated by the standard measurement
sequence [MDFR(1), CPDC(+), CPDC(-), MDFR(2), MDFR(2), CPDC(-), CPDC(+), MDFR(1)],
and most of the non-linear fluctuation averages out for the normal integration period of 10 s, it can
still contribute to the type-A uncertainty. Since the change in the output of the FRDC module
causes the change in the EMF output of the TCs, and the temperature coefficients of TC-output are
much larger than that of the FRDC circuit, the effect to the type-A uncertainty will be included in
the effect from the stability of TC module output discussed in the following paragraph.
On the other hand, typical short-term stability (0.03Hz to 3Hz) of the output of the FRDC module is
specified to be <10 ppm p-p. The equivalent low-frequency noise from the FRDC circuit is
calculated as (10 / 5) / √3 = 1.2 ppm/√Hz. For normal measurement sequence (40 s for positive and
40 s for negative), contribution to the type-A uncertainty is estimated to be 1.2 x (√2 / √40) = 0.26
ppm for each sequence, or 0.26 / √10 = 0.08 ppm for the average of 10 measurement sequence.
(2) Stability of TC EMF output
In the case of JSTC04 TC elements used in the standard TC modules, the temperature coefficients
of the output EMFs are of the order of 100 ppm/K, much higher than that of the output of FRDC
module. Hence the thermal guarding of the TC module against the change of the ambient
temperature is critically important for a precision measurement. The ET2001 control software
suspends measurement until proper drift-condition (<10 ppm/min) is established. The linear
component of the drift in the EMF output is compensated by the standard measurement sequence,
as in the case of the drift of an FRDC module. In this case, second-order drift during one set of
measurement (1 min) should not exceed one-half of the linear drift. Hence, fluctuation in the output
of a TC module (including the fluctuation in the output of FRDC module) should not affect the
measurement results by more than 5 x (1/2) =2.5 ppm for each sequence. The contribution to
FRDC-DC difference for the average of 10 measurement sequence is estimated to be 2.5 / (2*√10)
= 0.4 ppm, taking eq. (11.2) into account.
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Preliminary Version 1.03b
(3) Thermal noise in TC output
In addition to the effect of temperature variation, a fluctuation is contributed by the Johnson noise
of the thermocouple of TC. In the case of a JSTC04 TC elements which has 400 Ω EMF output
impedance, the Johnson noise of the thermocouple en is estimated as,
en (rms) ≅ 4 ×1.38 ×10 −23 (J / K ) × 300(K ) × 400(Ω)
,
(4.3)
≅ 2.6 nV / Hz
In this
€ case, the thermal noise from the TC is 0.43 ppm/√Hz with respect to the smallest total output
EMF of 3 mV (for JSTC04C-200 at 1V test voltage), taking square characteristic of TC into
account. For normal measurement sequence (40 s for positive and 40 s for negative), contribution
to the type-A uncertainty is estimated to be 0.43 x (√2 / √40) = 0.1 ppm for each sequence, or 0.1 /
√10 = 0.03 ppm for the average of 10 measurement sequence.
(4) Resolution of Detector
The ADC circuit, combined with back-up circuit, has typical resolution of better than 100 nV/√Hz.
This resolution amounts to 14.3 ppm/√Hz in the voltage resolution with respect to the total output
EMF of 7 mV, or 7.2 ppm/√Hz in the resolution for the FRDC-DC difference measurement
considering the square characteristic of the EMF output. Hence, the resolution of the detector
usually dominates the over-all resolution of the measurement system. For normal measurement
sequence (40 s for positive and 40 s for negative), contribution to the type-A uncertainty is
estimated to be 7.2 x (√2 / √40) = 1.6 ppm for each sequence, or 1.6 / √10 = 0.5 ppm for the average
of 10 measurement sequence at 7mV.
Assuming that measurement sequence will be repeated 10 times for each test frequency point, the
overall type-A uncertainty for the average of the 10 measurements is estimated to be 0.7 ppm. Since
the type-A uncertainty are strongly dependent on the measurement conditions, such as the stability
of the ambient temperature or possible interference from external noise, actual type-A uncertainty
must be calculated from the standard deviation (spread) of the 10 measurement sequence.
4.3.2. Type-B Uncertainties
Sources of type-B uncertainty in the FRDC-DC difference measurement for a "test"-TC module
(UUT) is as follows:
(1) Memory Effect
When an analog switch change from ON state to OFF state, electric charges are trapped in the FET
channel. When the switch becomes ON state again, these charges are released and injected to the
output current, resulting in the positive FRDC-DC difference proportional to switching frequency.
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Preliminary Version 1.03b
In the case of FRDC modules of ET2001 ADS system, the source A/B switching scheme is
employed in order to suppress the effect. The results from the FRDC-DC difference measurements
do not show such linear dependence with switching frequency, and hence the contribution of this
item is estimated to be within the maximum-resolution of the measurement system, i.e., 0.3 ppm.
The estimated standard (1s) uncertainty is 0.3/ √3 = 0.17 ppm, assuming uniform distribution.
(2) Interference Between the Sources
To obtain the equal RMS power for FRDC and DC modes, it is essential that there is no
interference between the Source A and Source B. This requirement may be confirmed using the
"isolation-test circuit" described in section 5.6.3. The contribution to the measurement uncertainty
should be within the maximum-resolution of the measurement system, i.e., 0.3 ppm. The estimated
standard (1σ) uncertainty is 0.3/ √3 = 0.17 ppm, assuming uniform distribution.
(3) Effect of off-time
If the period of the OFF-state is not long enough, the switching transients do not converge during
the off time, and there is a possibility of correlation between the waveform from the sources A and
B.
The effect can be checked experimentally by changing the off-time between 5µs to 200 µs. If no
change in the FRDC-DC difference is detected, the contribution to the measurement uncertainty is
estimated to be within the maximum-resolution of the measurement system, i.e., 0.3 ppm. The
estimated standard (1σ) uncertainty is 0.3/ √3 = 0.17 ppm, assuming uniform distribution.
(4) Mismatching of rms power
As in the case of AC-DC difference comparison measurement, mismatching of rms power between
the FRDC mode and the dc mode can cause thermal ripple, and contribute to the uncertainty due to
the nonlinear output characteristic of the TC under test. Hence, in the measurement program, all the
four sources (A±, B±) should be adjusted for equal outputs to within 100 ppm before each
measurement. If this precaution is taken, the contribution to the FRDC-DC difference should be
much smaller than 0.1 ppm.
(5) Output resistance of the source
Since the output impedance of the FRDC source is not zero, the value obtained in this condition
deviates from that for pure voltage mode to that for pure current mode. The degree of the deviation
is estimated by the ratio of output impedance of the source (0.1 Ω) to the minimum input resistance
of the TVC (100 Ω), and should be smaller than 0.1Ω 100Ω = 10 −3 . Since the absolute values of
FRDC-DC difference for normal TCs are smaller than 10 ppm, the deviation is estimated to be
much smaller than 0.1 ppm.
(6) High-Frequency Components
Some types of RF coaxial cables use Cu coated Fe wires as the inner conductors. If these cables are
used to connect the TVC with the FRDC source, it can cause FRDC-DC difference that increases
linearly with switching frequency due to a skin-effect. This effect occurs at the voltage mode, and
becomes significant for TVCs with low input resistance (<100Ω). Other magnetic materials such as
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Preliminary Version 1.03b
iron-clips should also be avoided. If these precautions are taken, the contribution from the skineffect should be much smaller than 0.1 ppm.
(7) Curve fitting
In the case of SJTC with measurable thermoelectric transfer difference, frequency-independent
part of the AC-DC transfer difference of TVC is determined from a curve fitting of FRDC-DC
difference data to the theoretical formula. The uncertainty in the curve fitting is evaluated from
relative deviation of the FRDC-DC difference data from the theoretical curve around 1kHz. This
uncertainty component may be omitted for MJTCs with non-measurable thermoelectric transfer
difference.
4.3.3. Uncertainties in Sensitivity Coefficient
The sources of uncertainty in the sensitivity coefficient measurement and its contribution to the
FRDC-DC difference results are evaluated in the following paragraph.
(1) Resolution of Detector
The relationship between the resolution of the EMF voltages (ΔE) and the error in the "index"
measurements (∂n) n is given by.
∂n ∂ (ΔE )
=
EDC
n
ΔE
.
EDC
(4.4)
The DAC circuit of the TC module has typical resolution of 14 ppm/√Hz in the voltage
resolution with respect
to the smallest output EMF of 7 mV (see technical reference "Hardware
€
manual"). For normal measurement sequence (10 s for -0.1%, 10 s for +0.1%, and 10 s for -0.1%),
contribution to the type-A uncertainty is estimated to be 14 x (√(1/10 +1/20)) = 5.2 ppm.
Combining the values ΔE/EDC ≈ 0.004 for ±0.1% change in the input, the uncertainties in the index
measurement (∂n) n are estimated to be <1.3x10-3. This estimation can be confirmed by repeating
the index measurement more than 10 times and calculating the standard deviation.
The relationship of the uncertainty in the index measurement (∂n) n and the uncertainty
contributed to the FRDC-DC difference is given by:
2
[∂ (δFRDC−DC )]
2
E
− EDC 
≅  FRDC

 nEDC

∂n 2
 n 
(4.5)
In the FRDC-DC difference measurement, the ac voltage is adjusted to the dc voltage such that
EFRDC should equal
€ to EDC within 100 ppm. Hence the uncertainty contributed to the FRDC-DC
difference measurement is estimated to be smaller than 0.13 ppm. The estimated standard (1σ)
uncertainty is 0.13/ √3 = 0.08 ppm, assuming uniform distribution in the adjustment.
(3) Output Linearity of FRDC module
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Preliminary Version 1.03b
Non-linearity in the voltage source can also be a source of error in the index-measurement.
Using (4.5), the uncertainty contributed to the FRDC-DC difference is evaluated to be:
∂ (ΔV ) ΔV 
∂ (δFRDC−DC ) ≅ δFRDC−DC 
.
VDC 
 VDC
(4.6)
In the case of an FRDC module of ET2001 ADS system, the linearity ∂(ΔV)/ΔV of the output of
FRDC for ±0.1%
change should not exceed more than 1%. Hence, the uncertainty contributed to
€
the AC-DC difference is estimated to be smaller than 1 % of the measured value. Assuming that
the FRDC-DC difference of the TC modules are <10 ppm, the uncertainty contributed to the ACDC difference is estimated to be 0.1 ppm in the worst case. The estimated standard (1σ) uncertainty
is 0.1/ √3 = 0.06 ppm, assuming uniform distribution in the frequency characteristic.
(3) Input Linearity of TC/AMP module
The TC/AMP module of the ET2001ADS system uses CS5532 Σ-D A/D converter, which has
integral non-linearity better than 10 ppm. Following the same calculation as in the case of the
resolution of detector (1), the contribution to the uncertainty is calculated as 0.13 x (10/5.2) = 0.25
ppm. The estimated standard (1σ) uncertainty is 0.25/ √3 = 0.15 ppm, assuming uniform
distribution in the frequency characteristic.
Since the measurements of the sensitivity coefficients ("index") are performed only once for
each test frequency point (or once for all the test points), the uncertainty in the index-measurement
must be evaluated as a type-B component.
4.3.4. Combined Uncertainty
The sources of uncertainty in the FRDC-DC difference measurement, performed on a 500Ω-input
JSTC04 element at 2V to 5V, are summarized in Table 4.1. The combined uncertainty is evaluated
by taking root-sum-square of all the uncertainty components.
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Preliminary Version 1.03b
(Numbers represents one standard deviation in µV/V)
Table 4.1 Uncertainty Budget for FRDC measurement
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Preliminary Version 1.03b
5. AC-LF Measurement
5.1. Executing Measurement
5.1.1. Measurement Procedure
The measurement procedure of an ACLF-AC difference measurement is basically the same as that
for standard AC-DC difference measurements, except that the standard sequence (AC/DC[+/-]/AC)
is replaced by (AC[test]/AC[ref]/AC[test]). Flow-chart of the automated measurement routine is
shown in Fig 5.1.
Start
Initialize
Input
Parameters
Measurement
Block #1
Set Meas.
Parameters
Measure
Index "n"
Measure at
AC [ref]
Measurement
Block #n
Measure at
AC [test]
Measurement
Sequence #1
Measure at
AC [ref]
Measurement
Sequence #m
Measurement
Block #N
Ending
Procedure
Calculate δ
Measurement
Sequence #M
Change
Mode
Wait for
Stabilization
DVM
Reading
Re-adjust
Sources
Store Data
to DISK
END
Fig 5.1 flow-chart of ACLF-AC difference measurement program.
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Preliminary Version 1.03b
After registering all the parameter or options, as described in chapter 3, the program will go to
stand-by mode, ready for a fully automated ACLF-AC difference measurement. When "GO" button
is pressed, the program will apply voltage to the TC module and wait for a specified period of time
(normally 10 minutes) to avoid the effects from initial warm-up drift. Then the program repeats the
following procedure (1) to (4) at each test points (Measurement Loops).
(1) Measurement of sensitivity index
The control program measures the normalized sensitivity index n of TC at each test point. The
normalized sensitivity indexes are measured by changing the input voltage by dV (normally 0.1%).
Influence of drift on the output voltage is removed by a measurement sequence [(V-dV) / (V+dV) /
(V-dV)].
NOTE ----- After repeating the index-measurement 10 times, the program proceeds to the
next stage with warning message that the drift is too large.
(2) Measurement sequence
A measurement sequence, [AC[ref] / AC[test] / AC(ref)], is used to eliminate the influence of
linear drift in DSS module output and EMF output voltage. The sequence is repeated for a specified
number of times (normally ten times) for each measurement point, and the average value and
standard deviation are calculated from the set of ten measurements. After each mode-switching, the
controller waits for a specified period (normally15 seconds) to avoid the output-transients, and then
takes the reading from ADC for a specified period (normally15 seconds).
(3) Determination of AC-AC difference
The AC-AC differences δ between the reference frequency and the test frequencies are calculated
by using formula (2.11).
(4) Storing measurement data
After measurement sequence, measurement conditions and measurement data of each test point are
stored to the hard disk of the measurement controller. The recorded items are listed in the following
sub-section.
After measurements for all test points are executed, a summery of measurement data are stored to
the hard disk of the system controller. Then instruments are reset to the initial condition preparing
for the exit from the measurement program. In the case of standard measurement conditions, one
measurement loop takes about half an hour. For a set of 12 standard test points from 4 Hz to 100Hz,
repeated two times (total 24 points), whole measurement takes approximately 16 hours.
5.1.2. Data Format
The results from the ACLF-AC difference measurement are stored into the specified data-file using
the same format as displayed in the [Data Recorded to File] window.
The data-file consists of the following records.
(1) Title "Data from ACLF-AC difference measurement."
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Preliminary Version 1.03b
(2) Revision Number of the control program
(3) Main header common to all measurement-blocks, including:
(3-1) Comment of the measurement,
(3-2) ID (serial) number of DSS module,
(3-3) Name, ID (serial) number, and description of TC/AMP module,
(3-4) Number of repetition for one measurement blocks,
(3-7) Waiting time before the ADC integration, and for initial warm-up time.
(3-8) Number of ADC sampling.
(4) Time constant of TC (measured).
(5) Data for one set of measurements, consisting of:
(5-1) Measurement block number,
(5-2) Date and Time of each measurement block,
(5-3) Test Voltage for each block,
(5-4) Test/Reference Frequency for each block,
(5-5) Result of TC Index measurement,
(5-6) Result of Source adjustments,
(5-7) Results of one measurement-sequence, consisting of:
(5-7-1) Measurement-sequence number,
(5-7-2) Time of each measurement-sequence,
(5-7-3) Temperature inside TC/AMP module,
(5-7-4) EMF outputs for each mode ([Ref]/[Test]/[Ref]),
(5-7-5) Average standard deviation of EMF outputs in ppm,
(5-7-6) ACLF-AC difference for each sequence in ppm,
(5-8) Average ACLF-AC difference for each measurement-block
(5-9) Standard deviation of ACLF-AC difference in ppm.
(6) Summary of the measurement.
(7) Error/Warning message during the measurement.
5.2. Evaluation of Uncertainty
In this section, the uncertainty is estimated for the Low-Frequency AC-AC difference (ACLF)
measurements. The sources of uncertainty are divided into two categories, namely, Type-A and
Type-B. The type-A uncertainties can be evaluated from actual measurement as the standard
deviation of the data, while the type-B uncertainties have to be estimated using different methods
depending on the nature of the sources of uncertainty.
5.2.1. Type-A Uncertainties
The type-A uncertainty in the evaluation of low-frequency characteristics of a "test"-TC module
(UUT) is composed of the following four components:
(1) Stability of DSS module output
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Preliminary Version 1.03b
In the case of the measurement with the ET2001 ADS system, typical thermal drift and short-term
stability (0.1Hz to 10Hz) of the output of the DSS module is specified to be <10 ppm/deg and <2
ppm, respectively. Though linear drift in the output is compensated by the standard measurement
sequence (AC[ref], AC[test], AC[ref]), and most of the non-linear fluctuation averages out for the
normal integration period of 10 s, it can still contribute to the type-A uncertainty. Since the change
in the output of the DSS module causes the change in the EMF output of the TCs, the effect to the
type-A uncertainty will be included in the effect from the stability of TC module output discussed
in the following paragraph.
On the other hand, typical short-term stability (0.03Hz to 3Hz) of the output of the DSS module is
specified to be <10 ppm p-p. The equivalent low-frequency noise from the DSS circuit is calculated
as (10 / 5) / √3 = 1.2 ppm/√Hz. For normal measurement sequence (20 s for AC[MES] and 20 s for
AC[REF]), contribution to the type-A uncertainty is estimated to be 1.2 x (√2 / √20) = 0.38 ppm for
each sequence, or 0.38 / √20 = 0.09 ppm for the average of standard 20 (10x2) measurement
sequence.
(2) Stability of TC module output
As in the case of the FRDC-DC difference, the ET2001 control software suspends measurement
until proper drift-condition (<10 ppm/min) is established. In this case, second-order drift during one
set of measurement (1 min) should not exceed one-half of the linear drift. Hence, fluctuation in the
output of TC module (including the fluctuation in the output of DSS module) should not affect the
measurement results by more than 5 x (1/2) =2.5 ppm for each sequence. The contribution to
ACLF-AC difference for the average of standard 20 (10x2) measurement sequence is estimated to
be 2.5 / (2*√20) = 0.28 ppm. (Please refer to section 4.3.2)
(3) Thermal noise in TC output
As in the case of the FRDC-DC difference, the effect of thermal noise of the 400 ohm thermocouple
en is estimated to be 0.43 ppm/√Hz. For normal measurement sequence (20 s for AC[MES] and 20 s
for AC[REF]), contribution to the type-A uncertainty is estimated to be 0.43 x (√2 / √20) = 0.14
ppm for each sequence, or 0.14 / √20 = 0.03 ppm for the average of standard 20 (10x2)
measurement sequence.(Please refer to section 4.3.2)
(4) Resolution of Detector
As discussed in section 4.3.2, the effect of The DAC circuit, combined with back-up circuit, has
typical resolution of better than 100 nV/√Hz. This resolution amounts to 25 ppm/√Hz in the voltage
resolution with respect to the total output EMF of 4 mV, or 12.5 ppm/√Hz in the resolution for the
ACLF measurement considering the square characteristic of the EMF output. For normal
measurement sequence(20 s for AC[MES] and 20 s for AC[REF]), contribution to the type-A
uncertainty is estimated to be 12.5 x (√2 / √20) = 3.9 ppm for each sequence, or 3.9 / √20 = 0.87
ppm for the average of standard 20 (10x2) measurement sequence.
(5) Effect of thermal ripple
When test frequency is below 100 Hz, and the integration time is not the exact multiple of the
inverse of the test frequency, thermal ripple in the output of the thermal converter may not be
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Preliminary Version 1.03b
averaged out and can contribute to the fluctuation in the ACLF measurement. In the case of
standard TC elements for ET2001 ADS system, JSTC04 and JSTC05, which have relatively large
thermal time constant of 2.8s and 6s respectively, no increase in the standard deviation is observed.
The total type-A uncertainty for each measurement sequence is estimated to be 1.28 ppm, taking
the RSS of the contribution from each source of uncertainty. Since the type-A uncertainty are
strongly dependent on the measurement conditions, such as the stability of the ambient temperature
or possible interference from external noise, actual type-A uncertainty must be calculated from the
standard deviation (spread) of the 10 measurement sequence. The calculated standard deviation
must be confirmed to be within the estimated value for the worst situation.
5.2.2. Type-B Uncertainties
Sources of type-B uncertainty in the evaluation of low-frequency characteristic of a "test"-TC
module (UUT) using a DSS module as the reference standard is as follows:
(1) DC offset in AC-output mode
The dc-offset voltage in the ac-mode causes a first-order thermoelectric effect in the EMF output.
The DSS module has the capability of adjusting the DC offset with resolution of 0.02%. In the case
of a TC elements that have reversal error of <100 ppm, the dc-offset of 0.02% may cause a
systematic error of 0.02 ppm in the AC-DC difference measurement.
(2) Effect of Dead-time
In the case of ET2001 system, the input voltages are switched by high-speed analog switches, and
the off-time is smaller than 1 _s. The effect of the off-time to the AC-DC difference measurement is
expected to be smaller than 0.01 ppm, and will not be included in the uncertainty budgets.
(3) High-frequency spurious noise
The synthesized sinusoidal waveform contains high-frequency spurious noise, mainly from
quantization noise of 10-bit D/A converter and clock feed-through at the sampling frequency. The
sampling frequency is 512 or 1024 times the basic (test) frequency and <1 MHz in the case of
ACLF-LF difference measurement. Since the frequency characteristic at 1Mz is smaller than 100
ppm and total power of the spurious noise is specified to be smaller than 1 ppm (-60dB),
contribution to uncertainty in the ACLF-AC difference measurement is estimated to be smaller than
0.01 ppm in the worst case.
5.2.3. Uncertainties in Sensitivity Coefficient
The sources of uncertainty in the sensitivity coefficient measurement and its contribution to the ACLF measurement results are evaluated in the following paragraph. Since the index measurement is
performed at DC output mode, the procedure for the evaluation of uncertainty is almost exactly the
same as in the case of the FRDC-DC difference measurement.
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Preliminary Version 1.03b
(1) Resolution of Detector
Contribution of the resolution of the EMF voltages (ΔE) to the measurement uncertainty via the
"index" measurements is the same as in the case of the FRDC measurement and is given by the
following two equations.
∂n ∂ (ΔE )
=
EDC
n
ΔE
.
EDC
(5.1)
2
€
[∂ (δ ACLF )]
2
 E( f ) − E( f0 ) 
≅

 nE( f0 ) 
∂n 2
 n 
(5.2)
The DAC circuit of the TC module has typical resolution of 25 ppm/√Hz in the voltage
resolution with
€ respect to the smallest output EMF of 4 mV. For normal measurement sequence (15
s for -0.1%, 15 s for +0.1%, and 15 s for -0.1%), contribution to the type-A uncertainty is estimated
to be 25 x (√(1/15 +1/30)) = 7.9 ppm. Combining the values ΔE/EDC≈0.004 for ±0.1% change in the
input, the uncertainties in the index measurement (∂n) n are estimated to be <2.0×10-3. This
estimation can be confirmed by repeating the index measurement more than 10 times and
calculating the standard deviation.
In the AC-LF measurement, the voltages at test frequencies are adjusted with respect to the
reference frequency within 20 ppm. Hence the uncertainty contributed to the AC-LF measurement
is estimated to be smaller than 0.04 ppm. The estimated standard (1σ) uncertainty is 0.04/ √3 = 0.02
ppm, assuming uniform distribution in the adjustment.
(2) Linearity in Output of DSS module
Non-linearity in the voltage source can also be a source of error in the index-measurement.
Using (5.2), the uncertainty contributed to the AC-DC difference is evaluated to be:
∂ (ΔV ) ΔV 
∂ (δ ACLF ) ≅ δ ACLF 
.
VDC 
 VDC
(5.3)
In the case of a DSS module of ET2001 ADS system, the linearity ∂(ΔV)/ΔV of the output of DSS
for ±0.1% change
should not exceed more than 1%. Hence, the uncertainty contributed to the AC€
DC difference is estimated to be smaller than 1 % of the measured value. Assuming that the
frequency characteristic of the TC module is better than 10 ppm from 10 Hz to 1kHz, the
uncertainty contributed to the AC-DC difference is estimated to be <0.1 ppm. The estimated
standard (1σ) uncertainty is 0.1/ √3 = 0.06 ppm, assuming uniform distribution in the frequency
characteristic.
(3) Input Linearity of TC/AMP module
The TC/AMP module of the ET2001ADS system uses CS5532 Σ-D A/D converter, which has
integral non-linearity better than 10 ppm. Following the same calculation as in the case of the
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Preliminary Version 1.03b
resolution of detector (1), the contribution to the uncertainty is calculated as 0.04 x (10/7.9) = 0.05
ppm. The estimated standard (1σ) uncertainty is 0.05/ √3 = 0.03 ppm, assuming uniform
distribution in the frequency characteristic.
Since the measurements of the sensitivity coefficients ("index") are performed only once for each
test frequency point (or once for all the test points), the uncertainty in the index-measurement must
be evaluated as type-B.
5.2.4. Combined Uncertainty
The sources of uncertainty in the ACLF-AC difference measurement are summarized in Table 5.1.
The combined uncertainty is evaluated by taking root-sum-square of all the uncertainty components.
(Numbers represents one standard deviation in µV/V)
Table 5.1 Uncertainty Budget for AC-LF measurement
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6. AC-DC Difference Measurement
6.1. Executing Measurement
6.1.1. Measurement Procedure
The procedure of an AC-DC or an AC-AC difference measurement employs the standard sequence
(AC/DC+/DC-/AC) or (AC/ AC[REF]/AC). Flow-chart of an automated measurement routine is
shown in Fig 6.1.
Start
Initialize
Input
Parameters
Measurement
Block #1
Set Meas.
Parameters
Measure
Index "n"
Adjust Sources
(DC- by DC+)
AC Mode
Adjust Sources
(AC by DC)
Measurement
Block #n
Measurement
Sequence #1
DC [-/+] Mode
AC Mode
Measurement
Sequence #m
Measurement
Block #N
Ending
Procedure
Change
Mode
DC [+/-] Mode
Wait for
Stabilization
Calculate δ
Measurement
Sequence #M
Re-adjust
Sources
Store Data
to DISK
END
Fig. 6.1 flow-chart of AC-DC difference measurement program.
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DVM
Reading
Preliminary Version 1.03b
After registering all the parameter or options, as described in chapter 3, the program will go to
stand-by mode, ready for a fully automated AC-DC (or AC-AC) difference measurement. When
"GO" button is pressed, the program will apply voltage to the TC module and waits for a specified
period of time (normally 10 minutes) to avoid the effects from initial warm-up drift. Then the
program repeats the following procedure (1) to (6) at each test points (Measurement Loops).
(1) Measurement of sensitivity indices
The control program measures the normalized sensitivity indices of two TVCs nX and nS at each test
point. The normalized sensitivity indices are obtained by changing the input voltage by dV
(normally 0.1%). Influence of drift of the output voltage is removed by a measurement sequence
[(V−dV) / (V+dV) / (V−dV)].
NOTE ----- After repeating the index-measurement 10 times, the program proceeds to the
next stage with warning message that the drift is too large.
(2) Adjustment of DC voltages
The negative DC output voltage (DC−) is adjusted to within 0.01% with respect to the positive DC
input modes (DC+).
NOTE ---- After repeating the adjustment five times, the program proceeds to the next stage
with warning message that the adjustment is not sufficient.
(3) Adjustment of AC voltage
Before adjusting the level of AC output voltage from DSS module, DC offset voltage in the AC
output waveform is adjusted within 0.01% (target 20 ppm). Then the AC output voltages at test
frequency, is adjusted to within 0.01% (target 20 ppm) of the average value of two DC input modes
(DC+, DC−).
NOTE ---- After repeating the adjustment five times, the program proceeds to the next stage
with warning message that the adjustment is not sufficient.
(4) Measurement sequence
A four-mode measurement sequence is used to eliminate the influence of linear drift in DSS
module output and EMF output voltage. Two slightly different sequence, [AC/ DC+ / DC- / AC]
and [AC/ DC- / DC+ / AC] is executed in turn to check possible hysteresis-effect in DC modes. For
an AC-AC difference measurement, the sequence is replaced by (AC/ AC[REF]/AC). The sequence
is repeated for specified number (normally ten times) for each measurement point, and the average
value and standard deviation are calculated from the set of ten measurements. After each modeswitching, the controller waits for a specified period (normally 15 seconds) to avoid the outputtransients, and then take the reading from ADCs for a specified period (normally 15 seconds).
(5) Determination of AC-DC difference
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The difference in the AC-DC differences (δx−δs) between the two TVCs, TVC-X and TVC-S, are
calculated by using formula (2.14).
(6) Storing measurement data
After measurement sequence, measurement conditions and measurement data of each test point are
stored to hard disk of measurement controller. The recorded items are listed in the following subsection.
After measurements for all test points are executed, summery of measurement data are stored to the
hard disk of the system controller. Then instruments are reset to initial condition preparing for the
exit from the measurement program. In the case of standard measurement condition, one
measurement loop takes about one hour. For a set of 17 standard test points from 10 Hz to 1MHz
repeated twice (total 34 points), whole measurement takes approximately 20 hours.
6.1.2. Data Format
The results from the AC-DC (AC-AC) difference measurement are stored into the specified datafile using the same format as displayed in the [Data Recorded to File] window.
The data-file consists of the following records.
(1) Title "Data from AC-DC (AC-AC) difference measurement."
(2) Revision Number of the control program
(3) Main header common to all measurement-blocks, including:
(3-1) Comment of the measurement,
(3-2) ID (serial) number of DSS module,
(3-3) Name, ID (serial) number, and description of TC/AMP modules,
(3-4) Number of repetition for one measurement blocks,
(3-7) Waiting time before the ADC integration, and for initial warm-up time.
(3-8) Number of ADC sampling.
(4) Time constant of TC (measured).
(5) Data for one set of measurements, consisting of:
(5-1) Measurement block number,
(5-2) Date and Time of each measurement block,
(5-3) Test Voltage for each block,
(5-4) Test (& Reference) frequency for each block.
(5-5) Results of TC Index measurement,
(5-6) Results of Source adjustments,
(5-7) Results of one measurement-sequence, consisting of:
(5-7-1) Measurement-sequence number,
(5-7-2) Time of each measurement-sequence,
(5-7-3) Temperature inside TC/AMP modules,
(5-7-4) EMF outputs for each mode,
(5-7-5) Average standard deviation of EMF outputs in ppm,
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(5-7-6) AC-DC (AC-AC) difference for each sequence in ppm,
(5-8) Average AC-DC (AC-AC) difference for each measurement-block
(5-9) Standard deviation of AC-DC (AC-AC) difference in ppm.
(6) Summary of the measurement.
(7) Error/Warning message during the measurement.
6.2. Evaluation of Uncertainty
In this section, the uncertainty is estimated for the AC-DC difference measurement. The sources
of uncertainty are divided into two categories, namely, Type-A and Type-B. The type-A
uncertainties can be evaluated from actual measurement as the standard deviation of the data, while
the type-B uncertainties have to be estimated using different methods depending on the nature of
the sources of uncertainty.
6.2.1. Type-A Uncertainties
The Type-A uncertainty in the calibration of a "test"-TC module (UUT) against the reference TC
module (REF) is composed of the following four components:
(1) Stability of the DSS module output
In the case of the measurement with the ET2001 ADS system, typical thermal drift and short-term
stability (0.1Hz to 10Hz) of the output of the DSS module is specified to be <10 ppm/deg and <2
ppm, respectively. As in the case of an FRDC or an AC-LF measurement, linear drift in the output
is compensated by the standard measurement sequence [AC(mes), AC(ref), AC(ref), AC(mes)], and
most of the non-linear fluctuation averages out for the normal integration period of 10 s.
Furthermore, in the case of an AC-DC difference measurement which includes two TC elements of
the same type, fluctuations in output EMF voltages from the two TC elements tend to cancel each
other. Since the change in the output of the DSS module causes the change in the EMF output of
the TCs, the effect to the type-A uncertainty will be included in the effect from the stability of TC
module output discussed in the following paragraph.
On the other hand, typical short-term stability (0.03Hz to 3Hz) of the output of the DSS module is
specified to be <10 ppm p-p. The equivalent low-frequency noise from the DSS circuit is calculated
as (10 / 5) / √3 = 1.2 ppm/√Hz. For normal measurement sequence (20 s for AC and 20 s for DC),
contribution to the type-A uncertainty is estimated to be 1.2 x (√2 / √20) = 0.38 ppm for each
sequence, or 0.38 / √20 = 0.09 ppm for the average of standard 20 (10x2) measurement sequence.
(2) Stability of TC module output
As in the case of the FRDC-DC difference or ACLF-AC difference measurement, the ET2001
control software suspends measurement until proper drift-condition (<10 ppm/min) is established.
In this case, second-order drift during one set of measurement (1 min) should not exceed one-half of
the linear drift. Hence, fluctuation in the output of TC module (including the fluctuation in the
output of DSS module) should not affect the measurement results by more than 5 x (1/2) =2.5 ppm
for each sequence. The contribution to AC-DC or AC-AC difference for the average of standard 20
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Preliminary Version 1.03b
(10x2) measurement sequence is estimated to be 2.5 / (2*√20) = 0.28 ppm. (Please refer to section
4.3.2)
(3) Thermal noise in TC output
As in the case of the FRDC measurement or ACLF measurement, the effect of thermal noise of the
400 ohm thermocouple en is estimated to be 0.43 ppm/√Hz. For normal measurement sequence (20
s for AC[MES] and 20 s for AC[REF]), contribution to the type-A uncertainty is estimated to be
0.43 x (√2 / √20) = 0.14 ppm for each sequence, or 0.14 / √20 = 0.03 ppm for the average of
standard 20 (10x2) measurement sequence.(Please refer to section 4.3.2)
(4) Resolution of Detector
As discussed in section 4.3.2, the effect of The DAC circuit, combined with back-up circuit, has a
typical resolution of better than 100 nV/√Hz. This resolution amounts to 25 ppm/√Hz in the voltage
resolution with respect to the total output EMF of 4 mV, or 12.5 ppm/√Hz in the resolution for the
ACLF measurement considering the square characteristic of the EMF output. For a normal
measurement sequence (20 s for AC and 20 s for DC), contribution to the type-A uncertainty is
estimated to be 12.5 x (√2 / √20) = 3.9 ppm for each sequence, or 3.9 / √20 = 0.87 ppm for the
average of standard 20 (10x2) measurement sequence.
(5) Effect of thermal ripple
When test frequency is below 100 Hz, and the integration time is not the exact multiple of the
inverse of the test frequency, thermal ripple in the output of the thermal converter may not be
averaged out and can contribute to the fluctuation in the AC-DC difference measurement. In the
case of standard TC elements for ET2001 ADS system, JSTC04 and JSTC05, which have relatively
large thermal time constants of 2.8s and 6s respectively, no increase in the standard deviation is
observed.
The total type-A uncertainty for each measurement sequence is estimated to be 7.x ppm, taking
the RSS of the contribution from each source of uncertainty. Since the type-A uncertainty are
strongly dependent on the measurement conditions, such as the stability of the ambient temperature
or possible interference from external noise, actual type-A uncertainty must be calculated from the
standard deviation (spread) of the 10 measurement sequence. The calculated standard deviation
must be confirmed to be within the estimated value for the worst situation.
6.2.2. Type-B Uncertainties
Sources of type-B uncertainty in the calibration of a "test"-TC module (UUT) against the reference
TC module (REF) is as follows:
(1) DC offset in AC-output mode
The dc-offset voltage in the ac-mode causes a first-order thermoelectric effect in the EMF output.
The DSS module has the capability of adjusting the DC offset with resolution of 0.02%. In the case
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Preliminary Version 1.03b
of TC elements that have reversal error of <100 ppm, the dc-offset of 0.02% may cause a
systematic error of 0.02 ppm in the AC-DC difference measurement.
(2) Frequency Characteristic of the circuit
At higher frequencies (>100 kHz), non-negligible effect may be contributed from parasitic
impedance of the input cable. The effect is strongly dependent on the system configuration, and it
is very important to evaluate the effect experimentally by changing the length of the input cable or
by changing the earth-guard configuration. In the case of the ET2001 ADS system, this effect is not
observed, or at least within the resolution (0.9 ppm) of the system. The estimated standard (1σ)
uncertainty is 0.9/ √3 = 0.5 ppm, assuming uniform distribution.
(3) Effect of Dead-time
In the case of ET2001 system, the input voltages are switched by high-speed analog switches, and
the off-time is smaller than 1 _s. The effect of the off-time to the AC-DC difference measurement is
expected to be smaller than 0.01 ppm, and will not be included in the uncertainty budgets.
(4) Harmonic distortion in AC output
Distortion of the sinusoidal waveform produces in higher order frequency components. Combined
with the frequency characteristic of the input circuit, the higher-order components may cause error
in rms power in the input voltage. Contribution to the measurement uncertainty is estimated by
multiplying the specified total harmonic distortion (up to 10th order) with possible frequency
characteristic in the input circuit (<10-4 @1MHz, <10-2 @10MHz) as 0.01 ppm for ≤100kHz, and
1.0 ppm for >100kHz to 1MHz.
(5) High-frequency spurious noise
The synthesized sinusoidal waveform contains high-frequency spurious noise, mainly from
quantization noise of 10-bit D/A converter and clock feed-through at the sampling frequency. The
sampling frequency is fixed at 32 MHz in the case of normal an AC-DC or an AC-AC difference
measurement, and total power is smaller than 1 ppm (-60dB). Hence, the contribution to uncertainty
in the AC-DC or an AC-AC difference measurement is estimated to be smaller than 1 ppm in the
worst case.
6.2.3. Uncertainties in Sensitivity Coefficient
The sources of uncertainty in the sensitivity coefficient measurement and its contribution to the ACDC difference results are discussed in the following paragraphs.
(1) Resolution of Detector
The relationship between the resolution of the EMF voltages (ΔX, ΔS) and the error in the
"index" measurements is given by.
∂nX ∂ ( ΔX)
=
nX
XDC
ΔX
,
X DC
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Preliminary Version 1.03b
∂nS ∂ (ΔS ) ΔS
=
.
nS
SDC
SDC
(6.1)
The DAC circuit of the TC module has typical resolution of 25 ppm/√Hz in the voltage
resolution with respect to the smallest output EMF of 4 mV. For a normal measurement sequence
(15s for -0.1%, 15 s for +0.1%, and 15 s for -0.1%), contribution to the type-A uncertainty is
estimated to be 25 x (√(1/15 +1/30)) = 7.9 ppm. Combining the values ΔX/XDC ≈ ΔS/SDC ≈ 0.004
for ±0.1% change in the input, the uncertainties in the index measurement (∂n) n are estimated to
be <2.0×10-3. This estimation can be confirmed by repeating the index measurement more than 10
times and calculating the standard deviation.
The relationship of the uncertainty in the index measurement (∂n) n and the uncertainty
contributed to the AC-DC difference comparison ∂ (δ X − δS ) is given by:
2
[∂ (δ
2
X
− δ S )]
2
2
 S − SDC   ∂nS   X AC − XDC   ∂n X 
≅  AC
 
 +
 

 nS SDC   nS   nX X DC   nX 
2
(6.2)
In the AC-DC difference comparison measurement, the ac voltage is adjusted to the dc voltage
such that XAC should equal to XDC within 100 ppm. Hence the uncertainty contributed to the ACDC difference comparison measurement is estimated to be smaller than 0.28 ppm. The estimated
standard (1σ) uncertainty is 0.28/ √3 = 0.16 ppm, assuming uniform distribution in the adjustment.
(2) Linearity in Output of DSS module
Non-linearity in the voltage source can also be a source of error in the index-measurement.
Using (3.3), the uncertainty contributed to the AC-DC difference is evaluated to be:
 ∂ (ΔV ) ΔV 
∂ (δ X − δS ) ≅ (δ X − δ S )
.
VDC 
 VDC
(6.3)
In the case of a DSS module of ET2001 ADS system, the linearity ∂(ΔV)/ΔV of the output of DSS
for ±0.1% change should not exceed more than 1%. Hence, the uncertainty contributed to the ACDC difference is estimated to be smaller than 1 % of the measured value. Assuming that the
frequency characteristic of the TC modules is better than 100 ppm from 10 Hz to 1kHz, the
uncertainty contributed to the AC-DC difference is estimated to be <1.0 ppm. The estimated
standard (1σ) uncertainty is 1.0/ √3 = 0.6 ppm, assuming uniform distribution in the frequency
characteristic.
(3) Input Linearity of TC/AMP module
The TC/AMP module of the ET2001ADS system uses CS5532 Σ-D A/D converter, which has
integral non-linearity better than 10 ppm. Following the same calculation as in the case of the
resolution of detector (1), the contribution to the uncertainty is calculated as 0.28 x (10/7.9) = 0.36
ppm. The estimated standard (1σ) uncertainty is 0.36/ √3 = 0.21 ppm, assuming uniform
distribution in the frequency characteristic.
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Preliminary Version 1.03b
Since the measurements of the sensitivity-coefficients ("index") are performed only once for each
test frequency point (or once for all the test points), the uncertainty in the index-measurement must
be evaluated as type-B.
6.2.4. Combined Uncertainty
The sources of uncertainty in the AC-DC or AC-AC difference measurement are summarized in
Table 6.1. The combined uncertainty is evaluated by taking the root-sum-square of all the
uncertainty components.
(Numbers represents one standard deviation in µV/V)
Table 6.1 Uncertainty Budget for AC-DC and AC-AC difference measurement
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Preliminary Version 1.03b
7. Evaluation and Calibration of TC modules
7.1. General Scheme
The ET2001 ADS may be used in two different stages in AC-DC transfer standard, i.e., (1)
evaluation of a “Reference” TC module (REF) as a primary AC-DC transfer standard, and (2)
calibration of other thermal converters (“UUT” or Unit Under Test) using the “Reference” thermal
converter. A simplified schematic diagram of traceability chain of AC-DC transfer standard is
shown in Fig. 7.1. In the first stage, a reference TC module is calibrated using an FRDC module, a
DSS module, a HF-TVC and a LF-TVC. The first stage realizes the treceability of the “Reference”
TC module to the SI unit, as described in section 1.3. In the second stage, thermal converters under
test (UUT) or conventional TVCs combined with AMP modules are calibrated by AC-DC
difference comparison measurements using the “Reference” thermal converter.
Calibration
Fig. 7.1. Schematic diagram for the calibration of thermal converters.
7.2. Evaluation of a Reference Thermal Converter
7.2.1. Method of Evaluation
As described in section 1.3, the AC-DC transfer difference of the “Reference” TC module is
evaluated by the combination of (1) frequency independent DC offset, (2) low-frequency
characteristic below 100 Hz, and (3) high-frequency characteristic above 10 kHz. In the following
sub-sections, an evaluation of a TC module, SN05110024, which has a 500Ω-input JSTC04 thermal
converter element, is explained in detail. After the evaluation, the TC module may be used as a
“REF” TC module to be used as a reference standard in the comparison measurements.
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Preliminary Version 1.03b
Fig. 7.2. Evaluation of “Reference” TC module.
7.2.2. DC Characteristics
The frequency independent part (DC offset) of the AC-DC transfer difference of the TC module
was evaluated by an FRDC-DC difference measurement at reversing frequency between 0.1 Hz
and 1 kHz. A typical result from FRDC-DC measurement, performed on a TC module
SN05110024, is given in figure 7.3. As the TC module shows negligibly small thermoelectric
effect, it is not possible to determine the thermoelectric time constant. Hence, the thermoelectric
transfer difference of the TC module was determined by the average of the FRDC-DC difference
between 100 Hz to 1 kHz, to be -0.15 ppm, -0.09 ppm, and 0.01 ppm at 3V, 5V, and 7V,
respectively.
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Preliminary Version 1.03b
Fig. 7.3. Result from FRDC-DC difference measurement.
7.2.3. Low Frequency Characteristics
The low-frequency characteristic (10 Hz - 100 Hz) of the TC module (SN05110024) was evaluated
by AC-AC difference measurement using an LF-TVC (SN66014) as a reference standard. The LFTVC was combined with an external 200 Ω resistor, and was used as a reference standard at 5V.
Figure 7.4 shows the result of an AC-AC difference measurement performed on the TC module at
test frequencies from 4 Hz to 600 Hz, with reference frequency at 1 kHz. From the result, the lowfrequency characteristics the TC module is evaluated by a curve-fitting of the data to the second
order polynomial in (1/f) to be:
δ LF [ppm] ≅ −7.9 f −1 [Hz −1 ] − 6.33 f −2 [Hz −2 ] .
(7.1)
Fig. 7.4. Result of AC-AC difference measurement with a LF-TVC.
7.2.4. High Frequency Characteristics
The high-frequency characteristic (10 kHz – 1 MHz) of the “Reference” TC module (SN05110024)
was calibrated using a HF-TVC (SN500-64001) as a reference standard. As described in a
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Preliminary Version 1.03b
seaparate technical referece "TC manual", frequency characteristics of the 500-Ω input HF-TVCs
are estimated to be:
γ 500 [ppm] ≅ (0.0 ± 7.5)f [MHz] .
(7.2)
Figure 7.5 shows the result from the AC-AC difference comparison measurement between the TC
module and the HF-TVC with reference frequency at 1 kHz. From the result of the comparison
measurement, the high-frequency characteristics of the “Reference” TC module (SN05110024) is
evaluated by a curve-fitting of the data to the second order polynomial to be:
δ HF [ppm] ≅ 21.04 f [MHz] − 5.25 f 2 [MHz 2 ] .
(7.3)
Fig. 7.5. Result of AC-AC difference measurement with a HF-TVC.
7.2.5. Over-all Characteristic
The over-all frequency characteristic of the AC-DC difference of the TC module is determined by
the three measurements described in the preceding subsections, i.e., (1) DC offset by FRDC-DC
difference measurement, (2) LF characteristic by AC-AC difference measurement with LF-TVC,
and (3) HF characteristic by AC-AC difference measurement with HF-TVC. In total, the AC-DC
difference of the “Reference” TC module (SN05110024) at 5V is characterized by the following
formula:
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Preliminary Version 1.03b
δTotal[ppm] ≅ − 0.09 − 7.9 f −1[Hz −1 ] − 6.33 f −2 [Hz −2 ]
+ 21.04 f [MHz] − 5.25 f 2 [MHz 2 ]
.
(7.4)
€
Fig. 7.6. Evaluated AC-DC difference of a “Reference” TC module (SN05110024).
7.2.6. Evaluation of Uncertainty
The sources of uncertainties in the evaluation of a “REF” TC module are summarized in Table 7.1.
The combined uncertainty is evaluated by taking root-sum-square of the uncertainty contributions
from the three measurements, i.e., (1) FRDC-DC difference measurement, (2) AC-AC difference
measurement with LF-TVC, and (3) AC-AC difference measurement with HF-TVC.
The thermoelectric transfer difference determined by the FRDC-DC difference measurement is a
DC quantity, and the uncertainty related to the measurement contributes to the AC-DC difference of
the reference thermal converter at all the frequencies, i.e., 10 Hz to 1 MHz. The uncertainty related
to the low-frequency characteristic of the reference thermal converter is contributed from (a) the
frequency characteristic of the LF-TVC, and (b) the AC-AC difference measurement with the LFTVC. The uncertainty related to the high-frequency characteristic of the reference thermal converter
is contributed from (a) the frequency characteristic of the HF-TVC, (b) effect from the “Built-in”
TEE, and (c) the AC-AC difference measurement with the HF-TVC.
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Preliminary Version 1.03b
Table 7.1. Uncertainty budget for self-calibration
7.3. Calibration of a Thermal Converter
7.3.1. Comparison of AC-DC transfer difference
After evaluating the “Reference” TC module (REF), the AC-DC difference comparison
measurement will be performed between the “Reference” TC module and a TC module under test
(UUT), and the TC module under test is calibrated against the “Reference” TC module. In most
cases, intermediate (or “Transfer”) standards are used for the calibration of “UUT” TC module to
avoid repeated use of the “Reference” thermal converter. The TC modules under test (UUT) are
usually standards sent from the client (secondary) standard laboratories to be calibrated by the host
(primary) laboratories. This is the typical procedure to establish the traceability-chain between the
host laboratories and the client laboratories.
Calibration
Fig. 7.7. Calibration of a TC module under test (UUT).
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Preliminary Version 1.03b
The “Transfer” standards may also be used for an “inter-laboratory” comparison between two
independent laboratories with primary AC-DC transfer standards. Though the ET2001 ADS system
is capable of realizing an independent AC-DC transfer standard, it is quite important to check its
conformity with the other independent laboratories. The conformity can most easily be verified by
transferring a TC module and compare calibration results between the laboratories.
In ether case, the calibration involves two calibration institutes, i.e., the "host/primary" institute
(S) and “client/secondary” institute (X). The client laboratory prepares a calibrated traveling
standard (TCX), and sends the TCX to the host laboratory. Then the host laboratory carries out the
calibration of the TCX against its primary standard, and then issues the calibration certificate. This
is the conventional scheme of the “inter-laboratory” calibration of AC-DC transfer standard.
Fig. 7.8. “Inter-laboratory” calibration (conventional scheme)
The AC-DC difference of the intermediate (Transfer) TC module is determined by the combination
of (1) results from the AC-DC difference comparison measurement between the “Transfer” TC
module and the “Reference” TC module, and (2) AC-DC difference of the “Reference” TC module
evaluated by the procedure described in the previous section. Figure 7.9 shows the result of
calibration of a “Traveling” TC module (SN4120020) by the reference TC module (SN05110024).
The two TC modules have the same type of the TC elements (type JSTC04E), and hence shows
similar frequency dependence in the AC-DC transfer difference.
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Preliminary Version 1.03b
Fig. 7.9.Calibration of a “Traveling” TC module by the reference TC module.
7.3.2. Evaluation of Uncertainty
The sources of uncertainties in the evaluation of a transfer TC module (TRANS) or TC module
under test (UUT) is summarized in Table 7.2. The combined uncertainty is evaluated by taking
root-sum-square of the uncertainty contributions, i.e., (1) uncertainty in the evaluation of the ACDC difference of the “Reference” TC module, and (2) uncertainty in the AC-DC difference
comparison measurement(s) between the two (or three) TC modules.
Table 7.2. Uncertainty budget for the calibration of a TC module
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Preliminary Version 1.03b
7.3.3. Remote Calibration
In the case of the AC-DC transfer standard, the remote calibration is performed using a thermal
converter as a traveling standard. The traveling standard is calibrated by a pilot (host) laboratory,
and is sent to another (client) calibration institute, where it is compared with a client's reference
thermal converter by AC-DC difference comparison measurements. The schematic diagram of the
remote calibration is illustrated in figure 7.10.
ET2001 ADS system is especially suited for the remote calibration, on condition that both the
host and client institute has the ET2001 ADS systems. In this case, a traveling TC module prepared
by the host institute will be sent to the client institute by post. The TC module of the ET2001
system is quite tough for the vibration or temperature change, and the no special care is required for
the transportation. After receiving the traveling TC module, client institute can simply connect the
traveling TC module with their TC module (UUT) and start the automated measurement program.
After finishing the comparison measurement, all the measurement data, including the fluctuation of
ambient temperature and identification of TC modules are automatically sent to the host laboratory
via email. When necessary, the measurement data can be sent to the host laboratory by email
throughout the measurement, so as to confirm proper measurement conditions. It is also possible to
remote-control the measurement program from the host institute using a remote-login operation of
the Internet.
Fig. 7.10. Remote or "E-trace" calibration
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Preliminary Version 1.03b
8. Supplementary Information
8.1. FACs
Q: Should the Shield (chassis) of the thermal converter connected to the Guard (shell of input
connector) of the AMP module?
A: Input-Lo and Guard of the AMP module are connected inside. If your thermal converter has
internal connection between chassis (Input-Lo) and Output-Lo, you do not have to connect Shield
of the thermal converter to the Guard of the AMP module. Please refer to the figures for proper
earth and ground connection.
Q: Is it possible to improve detection sensitivity by inserting nanovolt amplifier between the TC
and the AMP module?
A: A filter/amplifier specially designed for the thermal converter has been developed at NMIA. Sixfold increase is obtained in the case of SJTC. Contact address <ilya.budovsky@nmia.go.au>.
8.2. Trouble Shooting
Q: LED of USB/PS module do not turn on after setting power switch to ON position.
A: Safety switch (or circuit breaker) can accidentally be set due to mechanical shock or vibration
during the transportation. The safety switch is located near the voltage selector switch.
8.3. Acknowledgements
The ET2001 AC-DC transfer standard (ADS) has been developed through a collaborative
research project between SunJEM Co. and AIST. The project was carried out as part of the “etrace” project of supported by NEDO (New Energy and Industrial Technology Development
Organization). Detailed designing of the ADS was performed by Minoru Usuda and Shinichi
Koyano of SunJEM Co., Japan, and Shinzo Honda of Yatoro-Electronics Co., Japan. The JTSC04
Thermal Converter and HF/LF-TVC has been developed through a collaborative research project
between Nikkohm Co. and AIST, supported by Koji Shimizume, Kazuki Nishiya, Satoshi Nakano,
Kaname Kishino and Shigeru Hidaka of Nikkohm Co. Contribution and Supports from Kiyotada
Kato of SunJEM Co., and Hiroyuki Fujiki and Kunihiko Takahashi of AIST are gratefully
acknowledged.
8.4. Contact Address
[Purchase information]
- 75 -
Preliminary Version 1.03b
Key Techno Co., Ltd.
Fax: +81-3-3251-3166
Email: keytechno@pop14.odn.ne.jp
[Technical questions or comments]
IQUANTUM Co., Ltd.
FAX: +81-29-855-8171
Email: info@iquantum.jp
http://www.iquantum.jp
or
Hitoshi SASAKI
Nanoelectronics Research Institute, AIST
Email: hitoshi-sasaki@aist.go.jp
- 76 -
Preliminary Version 1.03b
Appendix-A: File Examples
[1] Example of Measurement Procedure List
[2] Example of TC module specifications File
[3] Data from a FRDC-DC Difference Measurement
[4] Data from an AC-LF Measurement
[5] Data from an AC-DC Difference Measurement
[6] Data from an AC-AC Difference Measurement
All the data/parameters are recorded in simple ASCII text formats using semicolons as dataseparators
An example of a data-file is listed below.
[1] Example of Measurement Procedure List
"FRDCproc.txt"
------------------------------------------------------3
Type1,7.50E-01,7.50E-01,1.00E-01,5.00E+03,33,repeat 2 times,frdc01V033P-1.txt
Type2,3.00E+00,1.00E+00,1.00E+02,1.00E+03,2,Meas at 5V,frdc03V002P-1.txt
Type3,1.00E+01,1.00E+01,5.00E-01,1.00E+00,33,repeat 2 times,frdc10V033P-1.txt
END
------------------------------------------------------"ACLFproc.txt"
------------------------------------------------------2
LF-1,8.60E+00,8.60E+00,5.00E+00,2.00E+02,96,Proc JSTC05A,aclf8p6V096-1.txt
LF-2,2.80E+00,4.00E+00,5.00E+00,2.00E+02,96,Proc JSTC05A,aclf4p0V096-1.txt
END
------------------------------------------------------"ACDCproc.txt"
------------------------------------------------------4
Quick-1,5.00E+00,5.00E+00,1.00E+01,1.00E+06,13, meas at 5V,acdc5p0V013-1.txt
Type2,1.00E+00,1.00E+00,1.00E+04,9.90E+05,24,for HF-TVC,acdc01V024P-1.txt
Type3,1.50E+00,1.50E+00,1.00E+04,9.90E+05,24,for HF-TVC,acdc1p5V24P-1.txt
Type4,1.00E+01,1.00E+01,1.00E+01,1.00E+06,34,repeat 2 times,acdc10V034P-1.txt
END
------------------------------------------------------Parameters;
(Head: number of registerd procedure files)
- 77 -
Preliminary Version 1.03b
1: Handle name
2: Min. test voltage (V)
3: Max. test voltage (V)
4: Min. test Frequency (Hz)
5: Max. test Frequency (Hz)
6: number of registerd test points
7: Discription
8: Filename
(EOF: “END”)
"frdc10V033P-1.txt"
------------------------------------------------------33
001,1.00E+01,1.00E+03
002,1.00E+01,1.00E-01
003,1.00E+01,2.00E-01
004,1.00E+01,5.00E-01
005,1.00E+01,1.00E+00
006,1.00E+01,2.00E+00
007,1.00E+01,5.00E+00
008,1.00E+01,1.00E+01
-------
SKIPPED ------
027,1.00E+01,1.00E+02
028,1.00E+01,2.00E+02
029,1.00E+01,5.00E+02
030,1.00E+01,1.00E+03
031,1.00E+01,2.00E+03
032,1.00E+01,5.00E+03
033,1.00E+01,1.00E+03
END
------------------------------------------------------"acdc10V034P-1.txt"
------------------------------------------------------96
1, 8.60E+00, 7.69E+01
2, 8.60E+00, 5.00E+00
3, 8.60E+00, 6.25E+00
4, 8.60E+00, 7.69E+00
5, 8.60E+00, 1.00E+01
6, 8.60E+00, 1.20E+01
7, 8.60E+00, 1.52E+01
8, 8.60E+00, 2.00E+01
9, 8.60E+00, 2.50E+01
10, 8.60E+00, 3.03E+01
11, 8.60E+00, 4.00E+01
12, 8.60E+00, 5.00E+01
-------
SKIPPED ------
- 78 -
Preliminary Version 1.03b
91,
92,
93,
94,
95,
96,
END
5.00E+00,
5.00E+00,
5.00E+00,
5.00E+00,
5.00E+00,
5.00E+00,
4.00E+01
5.00E+01
6.25E+01
7.69E+01
1.00E+02
2.00E+02
------------------------------------------------------"acdc10V034P-1.txt"
------------------------------------------------------34
001,1.00E+01,1.00E+03
002,1.00E+01,1.00E+01
003,1.00E+01,2.00E+01
004,1.00E+01,5.00E+01
005,1.00E+01,1.00E+02
006,1.00E+01,2.00E+02
007,1.00E+01,5.00E+02
008,1.00E+01,1.00E+03
-------
SKIPPED ------
027,1.00E+01,1.00E+04
028,1.00E+01,2.00E+04
029,1.00E+01,5.00E+04
030,1.00E+01,1.00E+05
031,1.00E+01,2.00E+05
032,1.00E+01,5.00E+05
033,1.00E+01,1.00E+06
034,1.00E+01,1.00E+03
END
------------------------------------------------------Parameters;
(Head: number of registerd test points)
1: Number
2: Test voltage (V)
3: Test Frequency (Hz)
(EOF: “END”)
[2] Example of TC Spec List
"TClist.txt"
------------------------------------------------------3
JSTC04A-10Vspecial,10,9,1200,2.8,Q,NIKKOHM MJTC with alpha 1000 ohm
CTCV-Canada with 667 Ohm,10,4.2,742,15,Q,CTVC 742 Ohm
JSTC04B-4Z01, 7, 80, 500, 2.8,Q,NIKKOHM MJTC
END
- 79 -
Preliminary Version 1.03b
------------------------------------------------------Parameters;
(Head: number of registerd TCs)
1: Name
2: Nom. voltage (V)
3: Nom. output (mV)
4: input resistance (Ω)
5: Time constant (s)
6: Quad/Linear
7: Discription
(EOF: “END”)
"SN04020017.txt"
------------------------------------------------------JSTC04A-4X09,7,80,500,2.8,Quad,Nikkohm JSTC04A-500 (4X09) without RR,END
------------------------------------------------------Parameters;
1: Name
2: Nom. voltage (V)
3: Nom. output (mV)
4: input resistance (Ω)
5: Time constant (s)
6: Quad/Linear
7: Discription
8:”END”
[3] FRDC-DC Difference Measurement
"FRDC2005-11-14-4.txt"
------------------------------------------------------Data from FRDC-DC Difference Measurement
(Program Version: 10.3.4)
Comment; FRDC inside Styroform New PCB(A&B) Capacitors Removed
FRDC ID; 04020003
TC ID; PTB-#11; 04020007;PTB PMJTC with alpha 1000 ohm
TC/Dummy Res.; 1090; 1000Ohm
Off-Time; 10us
Repetition.; 10times
Waiting Time; 10s;(Initilal);
ADC Reading; 63sampling
10min
- 80 -
Preliminary Version 1.03b
T.Const.;TCX;1.21s
Mes. No.= 1
Date/Time; 2005-11-14; 19:15:38
Test Voltage; 10; V
SW Period; 1; ms ; (1.0000E+03Hz)
TC Index; 1.9853
Adjust A+/-; 0; -.034
Adjust B+/-; -.046; -.068
Rep#; Time; TempX; Vac*(nV); Vdc+(nV); Vdc-(nV); Vac/(nV); Vsd(ppm); FRDCDC(ppm)
000; 19:18:37; 25.81; 8.2497254E+01; 8.2497415E+01; 8.2496447E+01;
8.2496685E+01; 5.24; -0.24
001; 19:21:26; 25.97; 8.2472484E+01; 8.2472692E+01; 8.2471963E+01;
8.2472254E+01; 5.34; -0.25
002; 19:24:15; 26.09; 8.2448336E+01; 8.2448513E+01; 8.2447810E+01;
8.2448087E+01; 4.96; -0.31
003; 19:27:05; 26.22; 8.2425030E+01; 8.2425247E+01; 8.2424603E+01;
8.2424739E+01; 4.84; 0.25
004; 19:29:54; 26.38; 8.2402519E+01; 8.2402745E+01; 8.2402219E+01;
8.2402451E+01; 4.63; -0.02
005; 19:32:43; 26.47; 8.2380814E+01; 8.2381061E+01; 8.2380598E+01;
8.2380688E+01; 4.57; 0.48
006; 19:35:32; 26.56; 8.2359848E+01; 8.2359910E+01; 8.2359462E+01;
8.2359817E+01; 4.50; -0.90
007; 19:38:21; 26.69; 8.2339611E+01; 8.2339799E+01; 8.2339494E+01;
8.2339469E+01; 4.33; 0.65
008; 19:41:10; 26.75; 8.2320144E+01; 8.2320277E+01; 8.2319943E+01;
8.2320181E+01; 4.15; -0.32
009; 19:43:59; 26.88; 8.2301290E+01; 8.2301417E+01; 8.2301120E+01;
8.2301292E+01; 4.18; -0.14
010; 19:46:48; 26.94; 8.2283141E+01; 8.2283104E+01; 8.2282910E+01;
8.2283083E+01; 3.77; -0.64
FRDC-DC diff;(in ppm); -0.12;
-------
+/- 0.46;(sd) ;(ex. #0)
SKIPPED ------
Mes. No.= 33
Date/Time; 2005-11-15; 16:36:22
Test Voltage; 10; V
SW Period; 1; ms ; (1.0000E+03Hz)
TC Index; 1.9826
Adjust A+/-; 0; -.036
Adjust B+/-; -.046; -.07
Rep#; Time; TempX; Vac*(nV); Vdc+(nV); Vdc-(nV); Vac/(nV); Vsd(ppm); FRDCDC(ppm)
000; 16:39:21; 28.91; 8.1833680E+01; 8.1834776E+01; 8.1832667E+01;
8.1833595E+01; 1.39; 0.52
001; 16:42:11; 28.91; 8.1833486E+01; 8.1834515E+01; 8.1832573E+01;
8.1833854E+01; 0.99; -0.77
002; 16:45:00; 28.91; 8.1833921E+01; 8.1834968E+01; 8.1833285E+01;
8.1834311E+01; 1.11; 0.06
003; 16:47:49; 28.88; 8.1834412E+01; 8.1835342E+01; 8.1833519E+01;
8.1834487E+01; 1.04; -0.11
- 81 -
Preliminary Version 1.03b
004; 16:50:38;
8.1834548E+01;
005; 16:53:27;
8.1834662E+01;
006; 16:56:17;
8.1834802E+01;
007; 16:59:06;
8.1834879E+01;
008; 17:01:55;
8.1835067E+01;
009; 17:04:44;
8.1835153E+01;
010; 17:07:33;
8.1835413E+01;
28.91; 8.1834449E+01;
1.05; 0.12
28.91; 8.1834569E+01;
0.97; 0.27
28.88; 8.1834687E+01;
1.02; -0.31
28.91; 8.1834794E+01;
1.05; 0.08
28.91; 8.1834887E+01;
1.03; 0.58
28.91; 8.1835066E+01;
1.07; 0.39
28.91; 8.1835286E+01;
1.07; -0.06
FRDC-DC diff;(in ppm); 0.02;
8.1835475E+01; 8.1833559E+01;
8.1835628E+01; 8.1833690E+01;
8.1835630E+01; 8.1833760E+01;
8.1835800E+01; 8.1833900E+01;
8.1836007E+01; 8.1834135E+01;
8.1836124E+01; 8.1834223E+01;
8.1836296E+01; 8.1834385E+01;
+/- 0.36;(sd) ;(ex. #0)
Mes#;
Time;
Level;;
Frequency;;
FRDC(ppm);;
1;19:46:49;10.00;V;1.00E+03;Hz;;-0.12;(;0.46;)uV/V
2;20:26:51;10.00;V;1.00E-01;Hz;;0.10;(;0.59;)uV/V
3;21:06:50;10.00;V;2.00E-01;Hz;;0.13;(;0.16;)uV/V
4;21:46:50;10.00;V;5.00E-01;Hz;;0.00;(;0.38;)uV/V
5;22:26:50;10.00;V;1.00E+00;Hz;;0.11;(;0.26;)uV/V
6;23:06:50;10.00;V;2.00E+00;Hz;;-0.16;(;0.27;)uV/V
7;23:46:50;10.00;V;5.00E+00;Hz;;0.03;(;0.37;)uV/V
8;00:26:51;10.00;V;1.00E+01;Hz;;0.02;(;0.13;)uV/V
9;01:06:51;10.00;V;2.00E+01;Hz;;-0.11;(;0.35;)uV/V
10;01:46:52;10.00;V;5.00E+01;Hz;;0.04;(;0.25;)uV/V
11;02:26:56;10.00;V;1.00E+02;Hz;;-0.26;(;0.50;)uV/V
12;03:06:58;10.00;V;2.00E+02;Hz;;-0.04;(;0.20;)uV/V
13;03:47:00;10.00;V;5.00E+02;Hz;;-0.14;(;0.32;)uV/V
14;04:27:01;10.00;V;1.00E+03;Hz;;-0.15;(;0.34;)uV/V
15;05:07:02;10.00;V;2.00E+03;Hz;;0.05;(;0.19;)uV/V
16;05:47:03;10.00;V;5.00E+03;Hz;;0.28;(;0.40;)uV/V
17;06:27:04;10.00;V;1.00E+03;Hz;;0.02;(;0.31;)uV/V
18;07:07:06;10.00;V;1.00E-01;Hz;;-0.07;(;0.41;)uV/V
19;07:47:13;10.00;V;2.00E-01;Hz;;-0.10;(;0.21;)uV/V
20;08:27:17;10.00;V;5.00E-01;Hz;;-0.12;(;0.31;)uV/V
21;09:07:18;10.00;V;1.00E+00;Hz;;0.06;(;0.18;)uV/V
22;09:47:20;10.00;V;2.00E+00;Hz;;0.12;(;0.15;)uV/V
23;10:27:22;10.00;V;5.00E+00;Hz;;-0.11;(;0.46;)uV/V
24;11:07:23;10.00;V;1.00E+01;Hz;;-0.21;(;0.32;)uV/V
25;11:47:24;10.00;V;2.00E+01;Hz;;0.09;(;0.35;)uV/V
26;12:27:25;10.00;V;5.00E+01;Hz;;-0.01;(;0.13;)uV/V
27;13:07:26;10.00;V;1.00E+02;Hz;;0.01;(;0.14;)uV/V
28;13:47:27;10.00;V;2.00E+02;Hz;;-0.03;(;0.55;)uV/V
29;14:27:28;10.00;V;5.00E+02;Hz;;0.04;(;0.18;)uV/V
30;15:07:30;10.00;V;1.00E+03;Hz;;-0.06;(;0.27;)uV/V
31;15:47:31;10.00;V;2.00E+03;Hz;;-0.04;(;0.16;)uV/V
32;16:27:33;10.00;V;5.00E+03;Hz;;0.49;(;0.16;)uV/V
33;17:07:34;10.00;V;1.00E+03;Hz;;0.02;(;0.36;)uV/V
(sd)
-------------------------------------------------------
[4] AC-LF Measurement
- 82 -
Preliminary Version 1.03b
"ACLF2005-06-07-1.txt"
------------------------------------------------------Data from LFAC-AC Difference Measurement
(Program Version: 10.2.6)
Comment; Test for PTB
DSS ID; 04020003
TCX ID; JSTC04A-4X09; 04020017;Nikkohm JSTC04A-500 (4X09) without RR
Repetition; 10times
Waiting Time; 10s;(Initilal);
ADC Reading; 63sampling
10min
T.Const.;TCX;2.93s
Mes. No.= 1
Date & Time; 2005-06-07; 10:14:28
Test Voltage; 5
Test/Reference Frequency; 100 100
TC Index (X); 1.9603
DSS AC Offset adjust; 0.80
DSS AC-DCp adjust; None
DSS DCm-DCp adjust; None
Rep#; Time; TempX; Xaclf(mV); sd(ppm); Xac-ref(mV); sd(ppm); LFAC-AC(ppm)
000; 30.03; 10:15:43; 4.0479869E+01; 12.74; 4.0479104E+01; 4.96; -9.64
001; 30.06; 10:16:47; 4.0477460E+01; 2.25; 4.0477501E+01; 2.49; 0.52
002; 30.09; 10:17:52; 4.0476602E+01; 2.64; 4.0476610E+01; 3.17; 0.11
003; 30.09; 10:18:56; 4.0476078E+01; 1.98; 4.0475868E+01; 3.39; -2.66
004; 30.13; 10:20:00; 4.0475477E+01; 2.47; 4.0475637E+01; 2.08; 2.02
005; 30.16; 10:21:05; 4.0474913E+01; 2.50; 4.0474949E+01; 3.43; 0.46
006; 30.19; 10:22:10; 4.0474157E+01; 2.19; 4.0474118E+01; 1.97; -0.49
007; 30.22; 10:23:14; 4.0473833E+01; 2.90; 4.0474005E+01; 2.42; 2.17
008; 30.22; 10:24:18; 4.0473129E+01; 1.86; 4.0473063E+01; 2.20; -0.83
009; 30.25; 10:25:23; 4.0472474E+01; 2.18; 4.0472417E+01; 2.83; -0.73
010; 30.28; 10:26:27; 4.0471949E+01; 2.75; 4.0471945E+01; 2.75; -0.05
LFAC-AC diff;(in ppm); 0.05;
-------
+/- 1.33;(sd) ;(ex. #0)
SKIPPED ------
Mes. No.= 24
Date & Time; 2005-06-07; 15:47:58
Test Voltage; 5
Test/Reference Frequency; 30.3 100
TC Index (X); 1.9580
DSS AC Offset adjust; 0.80
DSS AC-DCp adjust; None
DSS DCm-DCp adjust; None
Rep#; Time; TempX; Xaclf(mV); sd(ppm); Xac-ref(mV); sd(ppm); LFAC-AC(ppm)
000; 30.84; 15:49:14; 4.0447916E+01; 10.87; 4.0447442E+01; 2.49; -5.98
001; 30.84; 15:50:18; 4.0446130E+01; 2.00; 4.0446294E+01; 3.00; 2.07
002; 30.84; 15:51:23; 4.0446177E+01; 2.81; 4.0446211E+01; 3.13; 0.44
003; 30.84; 15:52:27; 4.0446178E+01; 3.09; 4.0446553E+01; 3.72; 4.74
004; 30.84; 15:53:32; 4.0446123E+01; 2.69; 4.0446445E+01; 3.58; 4.07
005; 30.84; 15:54:36; 4.0446167E+01; 2.87; 4.0446395E+01; 1.73; 2.89
006; 30.84; 15:55:41; 4.0446247E+01; 2.95; 4.0446424E+01; 3.30; 2.23
007; 30.81; 15:56:45; 4.0446317E+01; 2.31; 4.0446651E+01; 2.84; 4.22
- 83 -
Preliminary Version 1.03b
008; 30.84; 15:57:50; 4.0446350E+01; 3.58; 4.0446899E+01; 2.72; 6.94
009; 30.81; 15:58:54; 4.0446601E+01; 2.61; 4.0446792E+01; 2.36; 2.41
010; 30.81; 15:59:59; 4.0446386E+01; 4.40; 4.0446935E+01; 2.39; 6.92
ACLF-AC diff;(in ppm); 3.69;
+/- 2.00;(sd) ;(ex. #0)
Mes#;Time;Level;;Frequency;;ACLF(ppm);; (sd)
1;10:26:28;5.00;V;1.00E+02;Hz;0.05;(;1.33;)uV/V
2;10:42:31;5.00;V;8.00E+00;Hz;3.01;(;5.27;)uV/V
3;10:58:35;5.00;V;1.00E+01;Hz;6.81;(;4.36;)uV/V
4;11:12:56;5.00;V;1.20E+01;Hz;6.11;(;3.50;)uV/V
5;11:27:17;5.00;V;1.52E+01;Hz;3.13;(;3.36;)uV/V
6;11:41:38;5.00;V;2.00E+01;Hz;4.17;(;2.55;)uV/V
7;11:55:59;5.00;V;2.50E+01;Hz;3.62;(;1.76;)uV/V
8;12:10:20;5.00;V;3.03E+01;Hz;4.10;(;1.73;)uV/V
9;12:24:41;5.00;V;4.00E+01;Hz;3.34;(;1.22;)uV/V
10;12:39:02;5.00;V;5.00E+01;Hz;2.04;(;1.02;)uV/V
11;12:53:23;5.00;V;6.25E+01;Hz;1.89;(;1.03;)uV/V
12;13:07:44;5.00;V;7.69E+01;Hz;1.25;(;0.97;)uV/V
13;13:22:05;5.00;V;1.00E+02;Hz;-0.15;(;1.20;)uV/V
14;13:36:26;5.00;V;1.25E+02;Hz;-0.95;(;1.04;)uV/V
15;13:50:47;5.00;V;1.67E+02;Hz;-3.68;(;1.09;)uV/V
16;14:05:09;5.00;V;2.00E+02;Hz;-6.12;(;0.82;)uV/V
17;14:19:30;5.00;V;2.50E+02;Hz;-8.36;(;1.26;)uV/V
18;14:33:51;5.00;V;8.00E+00;Hz;6.93;(;4.82;)uV/V
19;14:48:13;5.00;V;1.00E+01;Hz;3.06;(;4.38;)uV/V
20;15:02:34;5.00;V;1.20E+01;Hz;4.10;(;3.14;)uV/V
21;15:16:56;5.00;V;1.52E+01;Hz;4.30;(;2.04;)uV/V
22;15:31:17;5.00;V;2.00E+01;Hz;2.79;(;1.87;)uV/V
23;15:45:38;5.00;V;2.50E+01;Hz;3.12;(;1.50;)uV/V
24;15:59:59;5.00;V;3.03E+01;Hz;3.69;(;2.00;)uV/V
-------------------------------------------------------
[5] AC-DC Difference Measurement
"ACDC2005-07-31-1.txt"
------------------------------------------------------Data from ACDC Difference Measurement
(Program Version: 10.3.4)
Comment; test program
DSS ID; 04020001
TCX ID; JSTC04A-4X07; 04020004;Nikkohm JSTC04B-200 device#4X07
TCS ID; JSTC04A 4X08; 04020003;
Repetition; 10times
Waiting Time; 15s;(Initilal);
ADC Read; 94sampling
10min
T.Const.;TCX;3.01s;TCS;2.92s
Mes.
Date
Test
Test
No.= 1
& Time; 2005-08-01; 00:04:11
Voltage; 3
Frequency; 10000
- 84 -
Preliminary Version 1.03b
TC Index (X/S); 1.9586; 1.9689
DSS AC Offset adjust; 0.60
DSS AC-DCp adjust; 0.6978
DSS DCm-DCp adjust; 0.2800
Rep#; Time; TempX; Xac(mV); sd(ppm); dXdc+(ppm); dXdc-(ppm); sd(ppm); TempS;
Sac(mV); sd(ppm); dSdc+(ppm); dSdc-(ppm); sd(ppm); AC-DC(ppm)
000; 00:06:19; 30.50; 3.4178678E+01; 2.01; 160.33; -190.98; 1.89 ; 30.69;
1.1629863E+01; 4.96; 7.39; -45.80; 5.97; 1.93
001; 00:08:11; 30.59; 3.4178484E+01; 2.23; -198.59; 143.28; 1.97 ; 30.72;
1.1629069E+01; 4.99; -34.45; -23.64; 4.76; 0.63
002; 00:10:18; 30.59; 3.4177946E+01; 2.63; 136.67; -212.86; 2.30 ; 30.81;
1.1628208E+01; 5.43; -16.82; -68.38; 5.48; 2.19
003; 00:12:25; 30.66; 3.4175820E+01; 3.08; -180.92; 149.12; 1.81 ; 30.91;
1.1626847E+01; 5.49; -20.22; -18.54; 4.94; 1.73
004; 00:14:17; 30.72; 3.4174861E+01; 2.17; 149.66; -199.91; 2.52 ; 30.97;
1.1625989E+01; 12.74; 0.24; -47.92; 4.91; -0.72
005; 00:16:25; 30.78; 3.4173455E+01; 2.32; -194.91; 128.29; 2.28 ; 31.03;
1.1625045E+01; 4.95; -34.62; -38.56; 5.98; 1.58
006; 00:18:32; 30.84; 3.4170764E+01; 3.10; 165.89; -184.78; 2.35 ; 31.13;
1.1623668E+01; 5.79; 7.75; -35.42; 4.87; 2.20
007; 00:20:24; 30.91; 3.4169202E+01; 2.57; -176.53; 143.69; 2.31 ; 31.19;
1.1622741E+01; 6.16; -18.09; -22.69; 6.08; 1.97
008; 00:22:31; 30.97; 3.4167335E+01; 3.54; 151.47; -197.93; 2.81 ; 31.28;
1.1621694E+01; 7.17; -6.66; -47.03; 6.14; 1.78
009; 00:24:38; 31.03; 3.4165581E+01; 2.18; -195.01; 119.26; 2.51 ; 31.38;
1.1620655E+01; 4.43; -37.39; -47.86; 6.04; 2.31
010; 00:26:46; 31.06; 3.4162112E+01; 3.27; 169.02; -178.58; 3.62 ; 31.44;
1.1619060E+01; 5.90; 14.26; -27.63; 6.42; 0.96
AC-DC diff;(in ppm); 1.46;
-------
+/- 0.89;(sd) ;(ex. #0)
SKIPPED ------
Mes. No.= 24
Date & Time; 2005-08-01; 11:04:46
Test Voltage; 3
Test Frequency; 990000
TC Index (X/S); 1.9584; 1.9717
DSS AC Offset adjust; 0.60
DSS AC-DCp adjust; 0.8634
DSS DCm-DCp adjust; 0.2796
Rep#; Time; TempX; Xac(mV); sd(ppm); dXdc+(ppm); dXdc-(ppm); sd(ppm); TempS;
Sac(mV); sd(ppm); dSdc+(ppm); dSdc-(ppm); sd(ppm); AC-DC(ppm)
000; 11:06:54; 32.97; 3.4125560E+01; 3.69; 287.56; -49.60; 2.15 ; 33.66;
1.1610328E+01; 5.63; 1.02; -22.40; 5.17; 66.18
001; 11:08:47; 32.97; 3.4125205E+01; 3.17; -45.63; 282.96; 1.75 ; 33.69;
1.1610000E+01; 5.32; -14.30; -10.93; 5.49; 66.99
002; 11:10:39; 33.00; 3.4124859E+01; 2.69; 283.99; -50.73; 2.31 ; 33.69;
1.1609798E+01; 4.85; -9.18; -22.82; 4.53; 67.67
003; 11:12:31; 33.03; 3.4124537E+01; 2.44; -49.30; 278.74; 2.08 ; 33.72;
1.1609645E+01; 4.90; -18.56; -12.59; 4.39; 66.48
004; 11:14:24; 33.03; 3.4124089E+01; 2.04; 283.17; -50.86; 2.38 ; 33.72;
1.1609494E+01; 4.58; -10.01; -22.26; 4.92; 67.49
005; 11:16:16; 33.03; 3.4123742E+01; 2.97; -49.44; 280.81; 1.93 ; 33.75;
1.1609402E+01; 5.87; -19.66; -10.09; 4.88; 66.62
006; 11:18:08; 33.09; 3.4123596E+01; 2.85; 279.39; -54.25; 2.15 ; 33.72;
1.1609386E+01; 5.22; -9.97; -24.10; 5.05; 66.12
- 85 -
Preliminary Version 1.03b
007; 11:20:01;
1.1609272E+01;
008; 11:21:53;
1.1609143E+01;
009; 11:23:45;
1.1609180E+01;
010; 11:25:38;
1.1609159E+01;
33.06; 3.4123169E+01; 2.61; -53.52;
4.65; -25.32; -11.65; 4.64; 66.98
33.06; 3.4122635E+01; 3.13; 286.68;
4.90; -7.34; -17.34; 4.70; 67.02
33.09; 3.4122478E+01; 2.70; -48.04;
4.65; -19.15; -10.84; 4.88; 66.88
33.09; 3.4122148E+01; 3.22; 284.62;
5.40; -8.08; -16.47; 4.78; 66.68
AC-DC diff;(in ppm); 66.89;
279.13; 1.82 ; 33.78;
-48.68; 2.23 ; 33.78;
280.20; 1.75 ; 33.78;
-47.84; 1.92 ; 33.78;
+/- 0.44;(sd) ;(ex. #0)
Mes#;Time;Level;;Frequency;;ACDC(ppm);; (sd)
1;00:26:46;3.00;V;1.00E+04;Hz;1.46;(;0.89;)uV/V
2;00:55:48;3.00;V;5.00E+04;Hz;5.08;(;0.82;)uV/V
3;01:24:36;3.00;V;9.00E+04;Hz;8.66;(;0.55;)uV/V
4;01:52:22;3.00;V;1.90E+05;Hz;15.50;(;0.51;)uV/V
5;02:20:58;3.00;V;2.90E+05;Hz;22.11;(;0.68;)uV/V
6;02:48:45;3.00;V;3.90E+05;Hz;28.61;(;0.87;)uV/V
7;03:18:11;3.00;V;4.90E+05;Hz;35.32;(;0.83;)uV/V
8;03:45:59;3.00;V;5.90E+05;Hz;41.28;(;0.81;)uV/V
9;04:16:25;3.00;V;6.90E+05;Hz;47.68;(;1.23;)uV/V
10;04:45:03;3.00;V;7.90E+05;Hz;53.71;(;1.61;)uV/V
11;05:13:06;3.00;V;8.90E+05;Hz;60.51;(;0.68;)uV/V
12;05:41:25;3.00;V;9.90E+05;Hz;67.38;(;0.51;)uV/V
13;06:10:00;3.00;V;1.00E+04;Hz;1.22;(;0.90;)uV/V
14;06:37:48;3.00;V;5.00E+04;Hz;5.36;(;0.67;)uV/V
15;07:06:26;3.00;V;9.00E+04;Hz;7.77;(;0.95;)uV/V
16;07:34:44;3.00;V;1.90E+05;Hz;15.02;(;0.77;)uV/V
17;08:04:10;3.00;V;2.90E+05;Hz;21.86;(;0.49;)uV/V
18;08:33:32;3.00;V;3.90E+05;Hz;28.37;(;0.89;)uV/V
19;09:03:09;3.00;V;4.90E+05;Hz;34.89;(;0.96;)uV/V
20;09:31:45;3.00;V;5.90E+05;Hz;41.32;(;0.94;)uV/V
21;09:59:34;3.00;V;6.90E+05;Hz;47.57;(;0.67;)uV/V
22;10:27:23;3.00;V;7.90E+05;Hz;54.30;(;0.75;)uV/V
23;10:56:58;3.00;V;8.90E+05;Hz;60.38;(;0.65;)uV/V
24;11:25:39;3.00;V;9.90E+05;Hz;66.89;(;0.44;)uV/V
-------------------------------------------------------
[6] AC-AC Difference Measurement
"ACAC2005-07-18-1.txt"
------------------------------------------------------Data from ACAC Difference Measurement
(Program Version: 10.4.5)
Comment; Chassis B with 2000-5119 (Normal Combination)
DSS ID; 04020003
TCX ID; JSTC04-100B5102; 04020009;
TCS ID; JSTC04A-5101; 04020005;Nikkohm JSTC04B-100 device#5101
Repetition; 10times
Waiting Time; 15s;(Initilal);
ADC Read; 94sampling
10min
T.Const.;TCX;3.03s;TCS;3.13s
- 86 -
Preliminary Version 1.03b
Mes. No.= 1
Date & Time; 2005-07-18; 15:30:08
Test Voltage; 1.5
Test/Ref Frequencies; 10000; 1000
TC Index (X/S); 1.9816; 1.9785
DSS AC Offset adjust; 0.82
DSS AC-DCp adjust; 0.4260
DSS DCm-DCp adjust; N/A
Rep#; Time; TempX; Xacx(mV); sd(ppm); dXacr1(ppm); dXacr2(ppm); sd(ppm); TempS;
Sacx(mV); sd(ppm); dSacr1(ppm); dSacr2(ppm); sd(ppm); AC-AC(1kHz)(ppm)
000; 15:32:02; 29.03; 1.8607843E+01; 3.66; 15.31; 5.02; 6.07 ; 28.88;
2.0442459E+01; 3.34; 20.27; 6.34; 5.02; -1.59
001; 15:33:39; 29.09; 1.8606713E+01; 4.17; 17.87; -0.35; 4.86 ; 28.94;
2.0441133E+01; 4.21; 20.55; 1.22; 5.23; -1.08
002; 15:35:17; 29.16; 1.8605618E+01; 4.06; 20.16; 8.74; 5.17 ; 29.06;
2.0439785E+01; 4.02; 23.98; 9.23; 5.97; -1.10
003; 15:36:55; 29.25; 1.8604489E+01; 3.72; 18.69; 4.66; 3.97 ; 29.06;
2.0438486E+01; 3.95; 15.81; 1.82; 4.32; 1.44
004; 15:38:33; 29.34; 1.8603350E+01; 6.08; 17.51; 13.05; 4.62 ; 29.13;
2.0437065E+01; 5.06; 20.40; 11.25; 4.67; -0.29
005; 15:40:10; 29.38; 1.8602068E+01; 5.07; 20.00; 3.15; 5.74 ; 29.19;
2.0435535E+01; 4.43; 24.00; 7.71; 5.91; -2.17
006; 15:41:48; 29.47; 1.8600769E+01; 5.28; 13.27; 2.07; 6.60 ; 29.25;
2.0434026E+01; 5.48; 15.46; 1.40; 4.71; -0.39
007; 15:43:26; 29.53; 1.8599508E+01; 4.06; 17.18; 1.30; 4.87 ; 29.31;
2.0432510E+01; 4.50; 19.74; 3.44; 6.30; -1.20
008; 15:45:03; 29.59; 1.8598361E+01; 5.37; 12.77; 7.76; 4.18 ; 29.38;
2.0431010E+01; 5.42; 19.33; 6.18; 5.46; -1.26
009; 15:46:41; 29.66; 1.8597491E+01; 3.65; 17.23; 7.94; 4.93 ; 29.44;
2.0429498E+01; 4.22; 23.43; 9.34; 5.36; -1.93
010; 15:48:18; 29.72; 1.8596650E+01; 3.93; 15.63; 5.10; 4.90 ; 29.50;
2.0428080E+01; 5.60; 16.16; 2.54; 5.50; 0.50
AC-AC(Ref) diff;(in ppm); -0.75;
-------
+/- 1.04;(sd) ;(ex. #0)
SKIPPED ------
Mes. No.= 24
Date & Time; 2005-07-19; 01:34:47
Test Voltage; 1.5
Test/Ref Frequencies; 990000; 1000
TC Index (X/S); 1.9759; 1.9783
DSS AC Offset adjust; 0.82
DSS AC-DCp adjust; 1.0831
DSS DCm-DCp adjust; N/A
Rep#; Time; TempX; Xacx(mV); sd(ppm); dXacr1(ppm); dXacr2(ppm); sd(ppm); TempS;
Sacx(mV); sd(ppm); dSacr1(ppm); dSacr2(ppm); sd(ppm); AC-AC(1kHz)(ppm)
000; 01:36:41; 35.97; 1.8430335E+01; 3.90; -149.59; -155.46; 4.33 ; 35.19;
2.0206679E+01; 4.38; 38.51; 32.66; 3.98; -95.18
001; 01:38:19; 35.94; 1.8430665E+01; 6.68; -154.42; -158.45; 3.54 ; 35.19;
2.0207003E+01; 6.58; 35.94; 32.15; 3.77; -96.38
002; 01:39:57; 35.91; 1.8431103E+01; 4.31; -154.69; -153.41; 4.14 ; 35.16;
2.0207471E+01; 4.11; 40.04; 40.07; 3.70; -98.21
003; 01:41:35; 35.91; 1.8431535E+01; 6.01; -152.61; -158.93; 3.44 ; 35.16;
2.0207939E+01; 4.95; 37.31; 32.26; 3.92; -96.42
- 87 -
Preliminary Version 1.03b
004; 01:43:12;
2.0208281E+01;
005; 01:44:50;
2.0208636E+01;
006; 01:46:28;
2.0208961E+01;
007; 01:48:06;
2.0209418E+01;
008; 01:49:43;
2.0209663E+01;
009; 01:51:21;
2.0209915E+01;
010; 01:53:00;
2.0210206E+01;
35.91; 1.8431856E+01; 7.35; -153.67;
6.61; 39.24; 35.96; 3.82; -97.54
35.88; 1.8432166E+01; 6.00; -154.76;
5.78; 36.32; 38.28; 3.68; -96.63
35.88; 1.8432470E+01; 7.90; -150.74;
6.57; 40.91; 31.31; 3.45; -97.15
35.91; 1.8432885E+01; 5.60; -157.74;
6.47; 38.28; 32.52; 4.61; -99.14
35.88; 1.8433101E+01; 6.83; -154.31;
5.74; 36.32; 36.79; 4.17; -97.49
35.84; 1.8433356E+01; 4.58; -145.69;
4.89; 45.58; 43.28; 4.36; -97.17
35.84; 1.8433592E+01; 6.26; -160.36;
6.51; 33.42; 39.69; 3.23; -97.95
AC-AC(Ref) diff;(in ppm); -97.41;
-156.67; 3.92 ; 35.16;
-152.59; 4.68 ; 35.13;
-161.04; 3.76 ; 35.13;
-163.32; 5.07 ; 35.09;
-157.93; 4.57 ; 35.13;
-149.55; 3.51 ; 35.13;
-153.71; 4.19 ; 35.13;
+/- 0.82;(sd) ;(ex. #0)
Mes#;Time;Level;;Frequency;;ACAC(ppm);; (sd)
1;15:48:19;1.50;V;1.00E+04;Hz;-0.75;(;1.04;)uV/V
2;16:12:32;1.50;V;5.00E+04;Hz;-5.50;(;1.14;)uV/V
3;16:35:55;1.50;V;9.00E+04;Hz;-10.49;(;0.85;)uV/V
4;17:00:58;1.50;V;1.90E+05;Hz;-23.00;(;1.04;)uV/V
5;17:26:00;1.50;V;2.90E+05;Hz;-35.14;(;1.32;)uV/V
6;17:52:39;1.50;V;3.90E+05;Hz;-46.65;(;1.43;)uV/V
7;18:19:20;1.50;V;4.90E+05;Hz;-56.73;(;0.89;)uV/V
8;18:46:50;1.50;V;5.90E+05;Hz;-67.42;(;0.94;)uV/V
9;19:13:31;1.50;V;6.90E+05;Hz;-74.78;(;0.83;)uV/V
10;19:40:13;1.50;V;7.90E+05;Hz;-82.44;(;0.90;)uV/V
11;20:06:53;1.50;V;8.90E+05;Hz;-89.32;(;0.78;)uV/V
12;20:34:20;1.50;V;9.90E+05;Hz;-97.21;(;0.44;)uV/V
13;20:58:35;1.50;V;1.00E+04;Hz;-0.65;(;1.05;)uV/V
14;21:21:11;1.50;V;5.00E+04;Hz;-5.83;(;1.15;)uV/V
15;21:45:26;1.50;V;9.00E+04;Hz;-10.17;(;1.19;)uV/V
16;22:10:27;1.50;V;1.90E+05;Hz;-23.17;(;0.94;)uV/V
17;22:37:06;1.50;V;2.90E+05;Hz;-34.98;(;0.69;)uV/V
18;23:03:44;1.50;V;3.90E+05;Hz;-46.34;(;0.52;)uV/V
19;23:30:24;1.50;V;4.90E+05;Hz;-56.67;(;1.08;)uV/V
20;23:57:55;1.50;V;5.90E+05;Hz;-66.40;(;1.35;)uV/V
21;00:26:10;1.50;V;6.90E+05;Hz;-75.33;(;1.21;)uV/V
22;00:52:50;1.50;V;7.90E+05;Hz;-83.44;(;0.87;)uV/V
23;01:22:53;1.50;V;8.90E+05;Hz;-91.25;(;1.32;)uV/V
24;01:53:01;1.50;V;9.90E+05;Hz;-97.41;(;0.82;)uV/V
-------------------------------------------------------
- 88 -