ERMTGSRR(15)022005
Title*: Proposal for measurement of TX Emissions
from Source*: Continental Automotive
Contact: Frank Gruson
input for Committee*:
ERM TGSRR
Contribution For*: Decision
Discussion
Information
X
Submission date*: 2015-10-28
Meeting & Allocation: ERMTGSRR#22 Relevant WI(s), or
deliverable(s):
ABSTRACT: Proposal to for measurement of TX power & alignment with ITU regulations
Introduction
In recent years, TG-SRR achieved significant achievements to align the HS (HENs) for TG-SRR
with ITU regulations.
Examples are (but are not limited to)



The definition of occupied bandwith according to RECOMMENDATION ITU-R SM.328-10
“SPECTRA AND BANDWIDTH OF EMISSIONS” (99% rule)
The definition of spurious measurements in line with CEPT/ERC/REC 74-01 (definition of 1
MHz reference bandwidth and mean = RMS detector)
The separation between “out of band” and “spurious” domain according to CEPT/ERC/REC
74-01
TG-SRR is obliged to ensure, that all these definition are properly transferred to the new HS
skeleton.
In addition, Continental proposes to add and clarify two new measurement items, namely
1.
2.
3.
4.
Antenna power (conducted power) and
Average eirp
Further clarification on OBW
And reference antenna gain
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ERMTGSRR(15)022005
Antenna power
Ancient systems specified an RF system by
1. The power into the antenna (conducted power)
2. The antenna gain
This makes sense for a sensor with replaceable antenna, but is not relevant for sensors with integral
antenna, as the antenna cannot be changed without damaging the sensor.
Furthermore, EU and CEPT regulations specify the effective isotropic radiated power (RMS and peak), as
this is the relevant quantity for interference compatibility analysis, where EIRP is

The product of “conducted power” (linear) x “antenna gain” linear (or the sum of these quantities in
dB)
Nevertheless, a definition of “antenna input power” is sometimes required in terms of “total output power” of
the SRR assuming a 100% lossless antenna.
At elevated frequencies, the measurement of the “antenna input power” is impossible without changing the
characteristics of the device (as this interface is not available).
Therefore we request the following definitions





“total output power” shall be measured in the unit mW or dBm
“total output power” shall be defined according to the theoretical antenna input power fed into an
ideal, lossless antenna (antenna input power to an ideal antenna)
“total output power” shall be measured by integrating the average power of an SRR over the
complete sphere (or semi-sphere, depending on the antenna characteristics)
“total output power” shall be alternatively determined by measuring average e.i.r.p. power (in units of
dBm) and substracting the gain of the antenna (dBi)
and “antenna input power” shall be defined according to the ITU radio regulations [1] according to
S1.159 carrier power (of a radio transmitter): The average power supplied to the antenna
transmission line by a transmitter during one radio frequency cycle taken under the condition of no
modulation.
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ERMTGSRR(15)022005
Average E.I.R.P.
Average e.i.r.p. (units of dBm) should be




clearly separated from the avererage spectral power density (units of dBm/MHz)
should resemble the average power within the specified bandwidth, measured with a thermal power
meter & an ideal, lossless channel filter
should be able to be measured using a spectrum analyzer
and should be defined as
- RMS power in a 1 MHz reference bandwidth
- integrated over the specified bandwidth
- using the “channel power” function of a modern spectrum analyzer
An example of such a measurement is shown in Fig 1.
Figure 1: Measurement of average e.i.r.p. by integrating the power within the specified bandwidth (here
80kHz) via the “channel power” function of a spectrum analyzer. The example shows the measurement of a
CW carrier, therefore the “peak value (28.80dBm)” equals the “RMS value (28.57dBm)” and equals the
“channel power” (28.88dBm)
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ERMTGSRR(15)022005
OBW
The definition of OBW should be enhanced by a reference to the ITU radio regulations [1]
S1.153 occupied bandwidth: The width of a frequency band such that, below the
lower and above the upper frequency limits, the mean powers emitted are each equal to a
specified percentage ß/2 of the total mean power of a given emission.
Unless otherwise specified in an ITU-R Recommendation for the appropriate class of emission, the
value of ß/2 should be taken as 0.5%.
Gain of reference antenna
6.3.6
Standard calibration method
The calibration of the test fixture establishes the relationship between the detected output from the test fixture, and the
transmitted power (as sampled at the position of the antenna) from the EUT in the test fixture. This can be achieved (at
higher frequencies) by using a calibrated horn with a gain of equal to or less than 20 dB, fed from an external signal
source, in place of the EUT to determine the variations in detected power over frequency.
The calibration setup is shown in Figure 1.
.
SPECTRUM ANALYZER
G_cable2
G_ATT
Cable 2
ATT
Test arrangement antenna
SIGNAL
GENERATOR
G_Tx
P_SG
max. 20 dBi
Cable 1
P_reading
Rx
LNA
Free space loss
Tx
Calibrated antenna
Cable 3
max. 20 dBi
G_cable1
G_LNA
G_fs_loss
G_Rx
G_cable3
Figure 1: Calibration set-up configuration


Calibrated antenna gain should be increased to 26dBi
“Calibrated” means
- experimentally measured
- or theoretically calculated by actual measured antenna aperture of the standard gain horn.
References
[1] Radio Regulations, INTERNATIONAL TELECOMMUNICATION UNION, Geneva 1998
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