Check Frequency And Phase Measurement Accuracy; Specifications Checked; Option 41 Frequency Accuracy And Channel Phase Difference - Tektronix VM700T User Manual

Check Frequency and Phase Measurement Accuracy

Specifications Checked

Option 41 Frequency
Accuracy and Channel
Phase Difference
VM700T Option 40/41/42 Audio Measurements User Manual
b. Set one sine-wave generator for a 2 V rms output at 1 kHz.
c. Set the second sine-wave generator for a 0.02 V (20 mV rms) at 3 kHz.
These two signals add across the termination resistance to produce a
1 kHz signal with a 1% third-harmonic distortion.
d. Run the Audio Analyzer measurement and check for a THD+N reading
of 0.9% to 1.1%.
e. Move the generator signals to the right channel input and repeat step 2,
part d.
3. Repeat step 2 for channels B and C; substitute the appropriate channel when
channel A is called for.
This procedure requires an accurate frequency generator or a digital counter to
set the frequency. The phase measurement requires that both channels have the
same signal applied.
This procedure checks the following parameters:
Frequency accuracy: 1 Hz (or 0.01% + 1 digit, whichever is worse) for
inputs of –60 dBu and greater in the frequency range of 20 Hz to 20 kHz.
Channel phase difference: 1 for inputs of 40 Hz to 20 kHz,
of 20 Hz to 40 Hz at levels of –40 dBu and greater.
1. As in Figure B-4, connect the sine-wave generator output to the Audio
board.
2. Set the sine-wave generator for a frequency and amplitude in the specified
frequency and amplitude range of the Audio option (20 Hz to 20 kHz,
amplitude of –60 dBu or greater).
NOTE. Use a test signal level of at least –60 dBu and test at least 10 frequencies
over the entire range. Tested frequencies should include the specification limits
(20 Hz, 20 kHz) and the 40 Hz breakpoint. Example frequencies to test might
also include the following: 100 Hz, 200 Hz, 1 kHz, 2 kHz, 10 kHz.
3. Check that the measured frequency is accurate to the limits shown in
Table B-4 for the applied test signal frequency and level, and that the phase
difference between channels meets the phase difference specification.
Appendix B: Verification Procedure
2 for inputs
B-13