Introduction to the Audio Precision APx555
The New Standard in High-Performance Audio Analysis
Agenda
† APx555 Overview
† APx555 High Performance Analog
Ö
Ö
Ö
Ö
Overview of Audio Distortion Measurements
Analog Architecture
System Distortion Performance
Compared to SYS-2722
† Advanced Digital I/O
† Advanced Master Clock
† Converter Testing with APx555
2
Unprecedented Performance
The APx555 Audio Analyzer
APx555 Overview
December 1, 2014
4
APx - A Family of Modular Audio Analyzers
APx515 APx525 APx526 APx582 APx585 APx586 APx555
Analog Channels
Output - Input
†
2-4
Measurement Bandwidth to 1 MHz
Modular Multi-channel Digital I/O
Ö
Ö
Ö
Ö
Ö
Ö
†
2-2
Dual and Multi-channel Analog I/O
Ö
†
2-2
AES/EBU, SPDIF, Optical
ASIO
Bluetooth
Digital Serial
HDMI
Pulse Density Modulation
Common Software Interface
Ö
Ö
Easy to use and automate
Interchangeable between models
December 1, 2014
5
2-8
8-8
8 - 16
2-2
The State-of-the-Art APx555
The APx555 is the industry leader, designed for audio
engineers who need the highest performance, lowest
distortion and greatest flexibility possible.
•
Specified THD+N of -117 dB + 1 μV (22 kBW)
•
< -120 dB typical
•
Measurement bandwidth up to 1 MHz
•
Unique analog-digital architecture surpasses analog
designs and digital-only converter-based designs.
•
Advance DSP measurements offer a wide array of
precise, high-speed measurements.
New with APx555
9 High Performance
Analog Hardware
Architecture
9 APx Software with
Bench Mode
9 Advanced Digital I/O
Interface
9 Advanced Master Clock
9 DCX-127 Multifunction
Support
9 Optional Digital
Interfaces
o Bluetooth
o DSIO
o HDMI
o PDM
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6
APx555 Hardware Overview
† APx Modular Configuration
Ö Analog Modules - Above
Ö Digital Modules - Below
Ö Ref/Sync, Auxiliary I/O, iButtons - Rear Panel
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7
APx555 Hardware Overview
Analog Modules
Ö
Ö
Ö
Ö
2 Analog Generator Outputs
2 Analog Analyzer Inputs
Balanced XLR & Banana Jacks
Unbalanced BNC
December 1, 2014
8
APx555 Hardware Overview
Digital Modules
† Advanced Digital I/O is
standard on APx555
† Optional
Ö
Ö
Ö
Ö
Bluetooth
Digital Serial I/O
HDMI
PDM
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9
APx555 Hardware Overview
† Advanced Master
Clock
Ö AES11 DARS I/O
Ö Sync I/O
Ö Trigger I/O
† Auxiliary I/O
Ö 8-bit Control
† iButtons
Ö Software Options
† USB PC
interface port
December 1, 2014
10
APx555 Analog Specifications
Analog Analyzer
Independent Analyzer Channels
Maximum Rated Input
Residual Input Noise (22kHz BW)
Input Crosstalk
CMRR
Switchable Input Terminations
Generator Monitor
Amplitude Accuracy (1 kHz)
Amplitude Flatness
Residual THD+N (22kHz BW)
DC Measurement Accuracy
Analog Generator
2
160 / 300 Vrms
1.0 uV
140 dB to 20 kHz
90 dB to 5 kHz;
80 dB to 20 kHz
600/300
Yes
Independent Output Channels
Max Output Vrms (Unb / Bal)
2
13.33 / 26.66
Max Output, dBm (600 Bal)
+30.17 dBm
Generator Output R Selections
Max Peak Output Current
Amplitude Accuracy (1 kHz)
Amplitude Flatness
0.03 / 0.05 dB
0.008 dB
-117 dB, Vin ≤9.3V;
-115 dB, Vin >9.3V
Sine Frequency Range
Signal Frequency Accuracy
U-20,50,75,100,600
B-40,100,150,200,600
80 mA
0.03 / 0.04 dB
0.008 dB
0.001 Hz-80 kHz, dac
5 Hz-204 kHz, osc
3 ppm, dac
0.3%, osc
-117 dB, Vin ≤9.3V;
-115 dB, Vin >9.3V
Yes
Multi-Tone Analysis
0.7% to ±160V
3 ppm
5 Hz to 1 MHz
0.15 deg to 5 kHz
0.6 deg to 20 kHz
Yes
Log Chirp Analysis
Yes
DFD IMD Test Signal
Yes
FFT Analysis
Yes
DIM Test Signal
Yes
Freq Measurement Accuracy
Phase Measurement Accuracy
Maximum FFT Frequency
Maximum FFT Length
Residual THD+N (22kHz BW)
Common Mode Test
IEC Common Mode Test
Yes
Squarewave Signal
Yes
SMPTE (MOD) IMD Test Signal
Yes
1 MHz
1.2M
Legend
State-of-the-art
Superior
December 1, 2014
11
APx v4.0 Software Overview
Two Modes of Operation
Ö Sequence Mode
† Measurement Oriented
† Easy to Use
† Best for Automated Test
„ Automated Measurement Sequences
„ Automated Reports
Ö Bench Mode
† Meter and Sweep Oriented
† Flexible and Interactive
† Best for Design and Troubleshooting
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12
Sequence Mode Interface
Measurement
Navigator /
Sequencer
Monitors
and Meters
Measurement Settings
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13
Measurement Results
Bench Mode Interface
Signal Path
Setup
•
•
•
•
•
•
Input/Output
References
Switchers
DCX
Clocks
Triggers
Generator / Analyzer
Measurements
Realt-time Monitors & Meters, Sweeps, FFT, Recorder,
Continuous Sweep, Acoustic Response
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14
APx555 High Performance Analog
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15
Non-Linearity and Distortion
†
†
†
The transfer function of a device describes how an input signal is
transformed to an output signal.
If the transfer function is perfectly linear, the output waveform is
an exact duplicate of the input waveform (except for possible gain,
loss, or inversion) depending on the slope of the transfer function.
If the transfer function isn’t linear, the output waveform is no
longer identical to the input. This is commonly referred to as
distortion.
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16
Harmonic Distortion
If a single, pure sinewave
is fed to a non-linear
device, the output signal
consists of:
† The original sinewave
† Harmonics
Ö
At exact integer
multiples of the original
sinewave frequency
† Noise
December 1, 2014
17
THD (Total Harmonic Distortion)
† THD is computed from a series of individual harmonic
amplitude measurements.
† The harmonic numbers, or the bandwidth included, must
be included in the specification: “THD, 2nd through 5th
harmonics” or “THD, all harmonics below 20 kHz”
† Individual harmonic amplitudes are combined on a RSS
(root-sum-square) basis to arrive at THD. For example,
given the following harmonic amplitudes:
Ö
2nd harmonic is -40 dB (0.010 x fundamental)
3rd harmonic is -50 dB (0.0031 x fundamental)
4th harmonic is -45 dB (0.0055 x fundamental)
5th harmonic is -55 dB (0.0017 x fundamental)
THD = SQRT(0.010^2 + 0.0031^2 + 0.0055^2 +
0.0017^2) = 0.0119 = -38.5 dB
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THD+N
Total Harmonic Distortion Plus Noise
† THD+N is the most common distortion
measurement method:
Ö THD+N provides a useful single number figure of
merit
Ö THD+N vs. frequency graphs
Ö THD+N vs. level graphs
† If the THD+N value is good, we know
that distortion, noise, hum, spurious
noise and alias products are all good
(everything the ear might hear).
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19
THD+N
Total Harmonic Distortion Plus Noise
† THD+N meters remove the fundamental frequency with
a notch filter, then measure everything remaining harmonics, wideband noise, hum, interfering signals, etc.
† Bandwidth must be specified for THD+N measurements.
Ö
Ö
Ö
Wideband noise may dominate the measurement.
High-order harmonics may affect the value.
THD+N without measurement bandwidth is a meaningless number.
December 1, 2014
20
THD+N Ratio vs. THD+N Level
† THD+N Level
Ö
The RMS level of the
signal after the notch filter
and bandwidth limiting
filters are applied.
† RMS Level
Ö
The level of the signal without
notch filtering.
† THD+N Ratio
Ö
The ratio of the THD+N
Level to RMS Level.
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21
Sweeps of THD+N vs. Level
†
Sweeps of input level versus output THD+N reveal nonlinear
behavior across the operational range of a device.
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22
Sweeps of THD+N vs. Frequency
†
Shows frequency dependent distortion characteristics:
Ö
Ö
Ö
Ö
Generator and notch filter frequencies are tuned to successive
frequencies and the distortion plotted.
When DUT is band-limited and has distortion above the noise floor
distortion may decline as frequency increases.
AC mains or power supply filter problems can be seen.
RC value and circuit feedback compensation problems can appear.
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Typical High-Performance Distortion Specifications
† A/D Converter, 32 Bit, 44.1 kS/s, 2.2 Vpp full
scale input
Ö -118 dB THD+N @ -1 dBFS input
measurement bandwidth 20 Hz to 20 kHz
Ö 121 Dynamic Range @ -60 dBFS input
measurement bandwidth 20 Hz to 20 kHz
† D/A Converter, 32 Bit, 44.1 kS/s, 3.05 Vpp full
scale output
Ö
Ö
-120 dB THD+N @ 0 dBFS output
measurement bandwidth 20 Hz to 20 kHz
133 dB Dynamic Range @ -60 dBFS output
measurement bandwidth 20 Hz to 20 kHz A-weighted
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24
APx555 Analog Hardware
Designed for low distortion THD+N measurements
High Performance Sine Generator
Ö
Ö
Ö
High Stability RC oscillator
High Frequency & Level Resolution
Low THD+N
High Performance Sine Analyzer
Ö
Ö
Ö
Combines analog notch filters and A-to-D converters
Low THD+N
Extremely flexible measurement bandwidth selection
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25
APx555 Analog Generator Architecture
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26
APx555 Analog Generator Architecture
Two waveform generators:
†
High Performance
Sine Generator
Ö
Ö
Ö
RC Oscillator
Sinewaves and Sine Burst
Extremely low
residual distortion and noise.
†
†
≤-117 dB + 1.0 μV for V ≤9.3 Vrms
≤-115 dB for V >9.3 Vrms to 26.66 Vrms
10 Hz to 20 kHz, 22 kHz BW
DSP + DAC
Ö
Low residual distortion and noise.
†
Ö
≤-105 dB + 1 μV, 10 Hz to 20 kHz, 22 kHz BW
Agile signal generation:
†
†
†
†
DC, low frequency sinewaves, split sine and dual sine, square waves,
continuous sweep sinewaves
IMD waveforms (twin-tone sinewaves and square waves), Noise
Multitones and arbitrary waveforms from files
Voice files for PESQ and POLQA
December 1, 2014
27
APx555 Analog Analyzer Architecture
With HPSA Off, the pre-notch A-to-D converter is used alone . . .
†
†
†
Bandpass filter is bypassed
Bandwidth increases: 500 kHz 2 channels, 1 MHz 1 channel
High bandwidth is suitable to test:
Ö
Out-of-band signals of D-to-A converters and spectra of spurious
signals above 5x fs at 192 kHz
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28
APx Audio Analyzer and Filter Architecture
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29
APx High & Low Pass Audio Filters
†
High Pass filters are 4-pole Butterworth
Ö
Ö
Ö
†
User-specified corner frequencies.
Designed for -3 dB at the corner frequency.
Familiar to 2700 Series users.
Low Pass filters are 8-pole Butterworth
or Elliptic
Ö
Ö
Ö
Ö
User specified corner frequencies.
Designed for flat response to the corner
frequency with -0.01 dB roll off.
Low pass-band ripple: ± 0.005 dB.
DSP “Warping” increases filter attenuation as
frequency approaches analyzer sample rate.
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30
APx555 High Performance Sine Analyzer
†
†
†
†
The High Performance Sine
Analyzer is activated by selecting
on the Input Configuration panel
Operates at bandwidths up to 250
kHz (2 channels), or 500 kHz (1
channel).
THD+N measurement performance
is ≤-117 dB (22 kHz BW)
Ö Typically < -120 dB at 1 kHz
Residual noise is ≤1 μVrms (22
kHz BW)
Ö Typically <6.2 nV/√Hz at 1 kHz
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31
APx555 High Performance Sine Analyzer
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32
APx555 High Performance Sine Analyzer
The High Performance Sine Analyzer utilizes two signal paths per channel.
†
Pre-notch A/D converter with DSP bandpass filter tuned to the fundamental
frequency.
Ö
†
Bandpass filter removes converter residual distortion and noise.
Analog notch filter tuned to the fundamental frequency.
Ö
Ö
≈ 60 dB notch depth
+22 dB analog gain prior to “post-notch” converter.
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33
APx555 High Performance Sine Analyzer
†
†
†
†
The Post-notch converter output is digitally attenuated 22 dB to
compensate for the analog gain amplifier.
A digital notch removes the remaining fundamental signal but not the
distortion components, noise, and interference signals.
The output of both signal paths is digitally summed to produce a low
distortion composite signal.
The digital composite signal improves measurement dynamic range
and lowers residual distortion.
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APx555 High Performance Sine Analyzer
†
Typical FFT spectrum of
the APx555
Ö
†
†
Typical THD+N < -120 dB
Typical APx555 Dynamic
Noise (DNR) is 125 dB
Ö
Ö
Ö
December 1, 2014
35
analog loopback mode
HPSG & HPSA together
analog loopback of -60
dBr (relative to 2 Vrms)
CCIR-2k weighting filter
20 kHz measurement
bandwidth
APx555 Typical THD+N vs. Frequency
Typical residual
THD+N performance
is 3-7 dB better than
specifications.
Graphs show the
measured THD+N vs.
Frequency for 22 kHz,
80 kHz, 250 kHz, and
500 kHz bandwidth
limiting selections.
Test Conditions:
†
High Performance
Sine Generator
loopback to High
Performance Sine
Analyzer
†
2 Vrms signal level
†
Low-Pass filters
22 kHz
80 kHz
250 kHz
500 kHz
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36
APx555 Analog Performance Compared
Analog Generator
Analog Analyzer
Characteristic ▼ Model ►
APx555
Independent Output Cha nnel s
SYS‐2722
Characteristic ▼ Model ►
Independent Ana l yzer Cha nnel s
2
2
160 Vrms
1.0 uV
1.0 uV
Input Cros s ta l k
140 dB to 20 kHz
140 dB to 20 kHz
CMRR
90 dB to 5 kHz;
80 dB to 20 kHz
80 dB to 20 kHz
600/300
600/300
Yes
Yes
2
13.33 / 26.66
13.33 / 26.66
Ma xi mum Ra ted Input
Ma x Output, dBm (600 Ba l )
+30.17 dBm
+30.17 dBm
Res i dua l Input Noi s e (22kHz BW)
U‐20,50,75,100,600
B‐40,100,150,200,600
U‐20,600
B‐40,150(200),600
80 mA
80 mA
0.03 / 0.04 dB
0.06 dB
Swi tcha bl e Input Termi na ti ons
0.008 dB
0.008 dB
Genera tor Moni tor
0.001 Hz‐80 kHz, da c
5 Hz‐204 kHz, os c
10 Hz‐60 kHz, da c
10 Hz‐204 kHz, os c
3 ppm, da c
0.3%, os c
3 ppm, da c
0.5%, os c
Common Mode Tes t
Yes
Yes
IEC Common Mode Tes t
Yes
No
Squa rewa ve Si gna l
Yes
Yes , opt BUR
SMPTE (MOD) IMD Tes t Si gna l
Yes
Yes , opt IMD
DFD IMD Tes t Si gna l
Yes
Yes , opt IMD
DIM Tes t Si gna l
Yes
Yes , opt IMD
Ma x Pea k Output Current
Ampl itude Accura cy (1 kHz)
Ampl itude Fl a tnes s
Si ne Frequency Ra nge
Si gna l Frequency Accura cy
State-of-the-art
Superior
Improved
December 1, 2014
Ampl i tude Accura cy (1 kHz)
0.03 / 0.05 dB
0.05 dB
0.008 dB
0.008 / 0.03 dB
‐117 dB, Vi n ≤9.3V;
‐115 dB, Vi n >9.3V ‐112 / ‐110.5 dB
DC Mea s urement Accura cy
0.7% to ±160V
No
Freq Mea s urement Accura cy
3 ppm
5 Hz to 1 MHz
6 ppm
10 Hz to 500 kHz
0.15 deg to 5 kHz
0.6 deg to 20 kHz
1 deg to 20 kHz
Mul ti ‐Tone Ana l ys i s
Yes
Yes
Log Chi rp Ana l ys i s
Yes
No
Ampl i tude Fl a tnes s
Res i dua l THD+N (22kHz BW)
Pha s e Mea s urement Accura cy
FFT Ana l ys i s
Legend
37
SYS‐2722
160 / 300 Vrms
2
Ma x Output Vrms (Unb / Ba l )
Genera tor Output R Sel ecti ons
APx555
Yes
Yes
Ma xi mum FFT Frequency
1 MHz
130 kHz
Ma xi mum FFT Length
1.2M
32k
APx555 vs. SYS-2722 Residual Distortion Spectrum
Typical System Residual THD+N Distortion FFT
SYS-2722 Typical System THD+N
-115 dB (22 kHz BW)
APx555 Typical System THD+N
-120 dB (22 kHz BW)
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38
Typical THD+N vs. Level Comparison
APx555 vs. SYS-2722 and APx525
@ 1 kHz (BW 22 Hz – 22 kHz)
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39
Typical THD+N vs. Level
THD+N vs. Level vs. Model
Lower THD+N is Better.
APx555 in Black
SYS-2722 in Blue
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40
APx555 Advanced Digital I/O
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41
Digital I/O
The Digital Audio Interface – What can go wrong?
†
†
†
†
Incorrect Sample Rate
Attenuated Pulse Amplitude
Slow Pulse Rise and Fall Times
Interfering signal and noise
Ö
Ö
†
†
December 1, 2014
Normal Mode - affects balanced and unbalanced
Common Mode - balanced (AES3) only
Jitter - many possible causes
Clock synchronization problems
42
ADIO - Advanced Digital I/O
† Digital Audio Input / Output
Ö Balanced AES-EBU (AES3)
Ö Unbalanced S/PDIF (IEC60958-3)
Ö Optical (EIAJ)
† Interface
Ö Output Impairments
Ö Input Measurements
† Jitter Generator and Demodulator
Ö Utilizes features of the Advanced Master Clock
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43
ADIO Output Impairments
† Audio Settings
Ö Sample Rate
Ö Bit Depth
Ö Dither
† Impairments
Ö Digital Pulse Level
†
Fixed or Custom
Ö Pulse Invert
Ö Rise Time
†
Fixed, Variable, or Cable
Simulation
Ö Common Mode Sine
†
AES/EBU balanced
interfaces only
Ö Noise
† Metadata
Ö User/Status Bits
Ö Forced Parity Error
Ö Validity Bits
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ADIO Output Impairments – Rise Time
† Fixed 12 ns
† Cable Simulation
† Custom
Ö
December 1, 2014
45
12 ns to 100 ns
ADIO Output Impairments – Common Mode Sine
†
†
Test common mode signal
rejection on a balanced
digital input
Applies an interfering
sinewave equally to both
sides of the balanced
connection to simulate
common mode noise
interference
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46
ADIO Output Impairments – Noise
†
†
†
†
To test the noise rejection capability of a digital device’s input
Applies interfering random white noise of variable amplitude to the serial bitstream
Noise is added at the BNC output
Noise is added as a “normal mode” signal (as opposed to “common mode”) at the
balanced XLR output
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ADIO Output Impairment Specs
Characteristic
Variable Rise/Fall Time
Range
Accuracy
Cable Simulation
Normal Mode Noise
Waveform
Unbalanced
Balanced
Common Mode Signal (Bal only)
Waveform
Frequency Range
Amplitude Range
December 1, 2014
Specifications
Supplemental Information
12 nsec to 100 nsec
±(10% + 2 ns)
1 ns typical resolution
Approximates the signal degradation of 100 meters of Belden 1696A
Psuedo‐random pulse train
0 to 635 mVpp, 2.5 mV steps ±(10% + 25 mV)
0 to 2.55 Vpp, 10 mV steps ±(10% + 100mV)
Sine
20 Hz to 100 kHz
0 to 20.0 Vpp, 24 mV steps: ±(10% + 50 mV)
48
ADIO Output Jitter Generator
† Sine, Square, Noise
† Frequency & Peak Level
Ö Peak Level in Seconds & UI
† Equalization for Jitter
Tolerance Tests
Ö Magnitude vs. Frequency
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49
ADIO Output Jitter Specifications
Output Residual Jitter
Characteristic
Specifications
Supplemental Information
700 Hz‐100 kHz BW
≤600 psec
Peak detection
50 Hz‐100 kHz BW
≤1.0 nsec
Peak detection
Residual Jitter
Unbalanced, Balanced
Optical
Typically <2.5 nsec, SR ≤96k
Output Induced Jitter
Characteristic
Induced Jitter (sine wave)
Frequency Range (FJ)
Amplitude Range
Amplitude Resolution
Accuracy (1 kHz)
Flatness
Jitter Spectrum
December 1, 2014
Specifications
2 Hz to 200 kHz
0‐10.0 UI at FJ ≤200 Hz
Supplemental Information
Above 200 Hz, maximum allowable jitter decreases in a "1/f" fashion to 0.20 UI at FJ =10 kHz and higher
1 nsec
±(10% + 1 nsec)
±0.5 dB, 100 Hz to 80 kHz
Spurious products are typically ‐40 dBc (below jitter signal) or ‐60 dBUI, whichever is larger
50
ADIO Inputs
†
†
†
†
†
Balanced, Unbalanced,
Optical
Bit Depth 8 to 24
Termination
Impedance
Audio or Jitter
measurements
Jitter Filters
Ö
Ö
Ö
High-pass: 700 Hz
(AES3) or 50 Hz
Low-pass: Butterworth
or Elliptic user-specified
frequency
Weighting: None, A-wt.,
B-wt., C-wt., CCIR 1-k,
CCIR-2k, CCITT, CMessage, 50 us deemph., 75 us de-emph.,
50 us de-emph. + A-wt.,
75 us de-emph. + A-wt.
December 1, 2014
51
ADIO Digital Interface Measurements
† Bits Meter
Ö
Active Bits & Data Bits
† Digital Waveform Level Meter
Ö
Pulse amplitude
† Sample Rate Meter
† Metadata Monitor
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52
ADIO Input Jitter Measurements
† Requires
Advanced
Master Clock
† Jitter waveform
† Jitter spectrum
† Jitter Meters
Ö
Ö
Ö
Ö
Ö
Ö
Ö
December 1, 2014
53
RMS Level
Average Level
Peak Level
Crest Factor
Bandpass Level
Frequency
Distortion
ADIO Input Specifications
Characteristic
Formats
Unbalanced
Balanced
Optical
Sample Rate (SR)
Range
Accuracy
Output Amplitude
Unbalanced
Range
Accuracy
Source Impedance
Balanced
Range Accuracy
Source Impedance
Optical
Channel Status Bits
User Bits & Validity Flag
December 1, 2014
Specifications
Supplemental Information
SPDIF‐EIAJ per IEC 60958
AES‐EBU per AES3‐2003
Toslink® or equivalent
28 kS/s to 200 kS/s
Usable over the extended range of 16 kS/s to 216 kS/s with degraded waveform fidelity, accuracy, and jitter
±0.0003% [3 ppm]
0.0 Vpp to 2.50 Vpp into 75Ω
±(8% + 20 mV)
10 mV resolution
Typically 75Ω
0.0 Vpp to 8.00 Vpp into 110Ω
±(10% + 80 mV)
40 mV resolution
Typically 110Ω
Fixed, determined by transducer
Full implementation per IEC‐60958 (consumer) Automatically set or manual override, hex and AES3 (professional)
or plain English
Fully settable
Hex
54
ADIO Input Jitter Specifications
Characteristic
Jitter Measurement
Range Detection
Bandwidth
High‐pass
Low‐pass
Accuracy (1 kHz)
Flatness
Residual Jitter
700 Hz ‐ 100 kHz BW
50 Hz ‐ 100 kHz BW
December 1, 2014
Specifications
Supplemental Information
0‐4.0 UI at FJ ≤500 Hz
Above 500 Hz, maximum allowable jitter decreases in a "1/f" fashion to 0.20 UI at FJ =10 kHz and higher
"Peak" detection must be used for residual measurements per AES3. "Average" detection is recommended for jitter response measurements.
Peak, Rms, or Average
50 Hz or 700 Hz (AES3)
1K to 150 kHz
±(10% + 1.0 ns)
±0.5 dB, 100 Hz to 80 kHz
≤600 psec
≤1.0 nsec
55
APx555 Advanced Master Clock
December 1, 2014
56
Advanced Master Clock (AMC)
Applications
† Synchronize a digital device clock rate to the APx digital
word clock.
† Synchronize the APx digital word clock to a digital device
clock rate.
† Trigger external devices / Trigger APx measurements
Advanced Master Clock
Rear panel connectors:
† AES11 Digital Audio
Reference Signal
(DARS) Reference in
and out.
† Clock Sync In and Out.
† Trigger In and Out.
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57
AMC – Reference/Sync Out
†
Reference Out is a DARS AES11 signal
Ö
Ö
†
†
Embedded audio is digital “black”
Connect to devices with AES3 XLR reference inputs
Sync Output is a logic level square wave signal output at the rear
panel BNC referenced to the APx time base
Reference/Sync Out Controls
Ö
Output Rate
†
†
Ö
Ö
Track Output Rate
Custom Rate
Sync Out Level
Sync Out Polarity
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58
AMC – Reference / Sync In
†
†
†
†
Reference Input receives an AES
reference signal.
Sync Input receives a logic level
square wave signal input at the
rear panel BNC
Locks to the input rate within
±100 PPM of the Ext. Reference
Rate control setting
Reference/Sync Input Controls
Ö
Timebase Reference
†
†
†
Ö
Ext. Reference Rate
†
Ö
Internal
Ext. AES11 DARS (XLR)
Ext. Sync (BNC)
Enter rate within ±100 PPM
DARS Termination
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59
AMC External Trigger
† Trigger Output Source
Ö Off
Ö Audio Generator
Ö Jitter Generator
† Trigger Input
Ö Logic Level
Ö Edge
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60
AMC External Trigger Output
Output Trigger Points
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61
AMC External Trigger Input
December 1, 2014
62
Advanced Master Clock Specifications
Characteristic
Sync Input
Signal Compatibility
Voltage Range
Frequency Range
Lock Range
Sync Output
Signal
Amplitude (VH)
Frequency Range
Reference Input (AES3 / DARS)
Voltage Range
Sample Rate Range
Lock Range
Reference Output (AES3 / DARS)
Amplitude
Sample Rate Range
Trigger Input
Voltage Range
Trigger Threshold Range
Minimum Pulse Width
Trigger Output
Trigger Sources
Amplitude (VH)
December 1, 2014
Specification
Supplemental Information
Square or Sine
0.8 Vpp to 5.0 Vpp
4 kHz to 50 MHz, square; 1 MHz to 50 MHz, sine
Rin >10 kΩ, AC coupled Typically 100 ppm
Square
+0.8 V to +3.6 V, 0.1 V steps
0 to 56 MHz
2.0 Vpp to 6.0 Vpp
4 kS/s to 216 kS/s
VL ≈ 0‐0.1 V
Maximum recommended frequency when interfacing to low voltage logic: 50 MHz for VH = 1.5‐2.0 V; 30 MHz for VH = 1.0‐1.4 V; 10 MHz for VH = 0.8‐0.9 V
Rin selectable: >5 kΩ or ≈110Ω
Typically 100 ppm
5.0 Vpp into 110Ω, balanced
27 kS/s to 216 kS/s
‐0.5 V to +5.5 V
+0.4 V to +3.6 V, 0.1 V steps
Usable below 27 kS/s with some loss in waveform fidelity
Rin ≈10 kΩ, DC coupled, positive or negative edge selectable
Typically 20 nsec
Analog Sine, Sine Burst, Jitter Generator Sine, Square Wave, IMD Freq 1, DIM, Arbitrary Waveform Start
+0.8 V to +3.6 V, 0.1 V steps
VL ≈ 0‐0.1 V
63
APx Software Automation
† Software settings, waveforms, images, and
measurement results data are stored in a single
“project” file
Ö
Simplifies maintenance by avoiding a collection of separate files
(the 2700 paradigm)
† Project files automatically translate for different models
of APx analyzers
Ö
Ö
Projects developed on one model may be re-used on another
model
Supports the entire line of APx analyzers
† Native .NET API supports all development languages:
Microsoft C++ / VB / C#, LabVIEW, VEE, MATLAB,
Python
Ö
Ö
Provides Intellisense for MS Visual Studio
API browser simplifies software development
December 1, 2014
64
Converter Testing with APx555
December 1, 2014
65
Converter Testing with APx555
APx555 satisfies AES17 test requirements
† AES17 recommends audio testing methods for digital
audio devices
Ö
Ö
A-to-D, D-to-A, D-to-D
Products and Components
† High bandwidth analog stimulus and measurement
Ö
192 kS/S requires sinewaves above 200 kHz for pass band and
stop band attenuation
† Low distortion sinewave stimulus and analysis
Ö
THD+N Ratio measurements below -115 dB
† Digital interfaces
Ö
AES/EBU, SPDIF, Optical, Serial (I2S, DSP, Custom)
† Jitter tolerance measurements
December 1, 2014
66
Technote 124
† How to measure A/D
and D/A converters
with APx555.
† APx project files
Ö All AES17
measurements.
Ö Common data book
measurements.
Ö Complete reports.
† Available for
download
December 1, 2014
67
Technote 124 Example Measurements
December 1, 2014
68
Unprecedented Performance
The APx555 Audio Analyzer