3-110
Performance Tests
SDH Transmit/Receive Jitter Amplitude Accuracy
32 Set the Calibration Pattern to ALT
33 Change the Jitter Frequency to 2.5 kHz and adjust the Spectrum Analyzer span
to approx 5 times the Jitter frequency.
34 Adjust the HP 37718A jitter amplitude (approximately 7.52 UI) until the 4th
Bessel Null is observed on the Spectrum Analyzer i.e 4th dip in the carrier level
(see Figure 3-10). For STM-4 use 11.52 UI, 6th null. For STM-16 use 9.52 UI,
5th null.
35 Set the Calibration Pattern to OFF. Check that there are no SDH errors.
36 Set the Receiver Filter to LP+HP1. Select . Press RUN to start the
measurement.
Check the TX Jitter UI p-p setting is between 7.10 and 7.94 UI p-p.
Check the RX Jitter results are between 6.756 and 8.164 UI p-p.
37 Press STOP to halt measurement.
38 Set the Calibration Pattern to ALT
39 Change the Transmit Jitter Range to 50UI and Receiver Measurement Type to
EXTENDED.
40 Change the Jitter Frequency to 50Hz and Jitter Amplitude to 33UI p-p.
NOTE Set the Spectrum Analyzer Span to approx 7 kHz and adjust Bandwidth & Sweep
Time controls as necessary. Measure the peak to peak deviation of the carrier using
markers. Adjust the Jitter Amplitude until the deviation at the amplitude peaks is 4.95
± 0.05 kHz.
NOTE It may be necessary to use an external modulation source to give better amplitude
resolution to optimise the measurement . The HP 37718A is set to accept External
modulation source and the synthesizer is set to the same jitter frequency as used for
Internal modulation and the level is fine adjusted to the desired frequency span.
RESULTS
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