HP 37718A Installation And Verification Manual page 136

N OTE
Performance Tests
PDH Transmit/Receive Jitter Amplitude Accuracy
18 Select
RESULTS
Second, Manual). Set to Multiple Window to allow observation of TX/RX Jitter
and Results pages.
19 Check the Receiver AIS Led is on.
20 Set the Spectrum Analyzer as follows:
Centre Frequency - 2048 kHz
Frequency Span - 25 kHz
Reference Level - 0 dBm
Sweep Time - 1.0 s
Video Bandwidth - 1 kHz
Resolution Bandwidth - 100Hz
21 Adjust the HP 37718A jitter amplitude until the second Bessel Null is observed
on the Spectrum Analyzer i.e second dip in the carrier level.
22 Ensure the Jitter amplitude displayed on the HP 37718A TX display is between
the minimum and maximum limits given in Table 3-5.
To optimize Bessel Null to check the Receiver Accuracy it is necessary to use an
external modulation source to give better amplitude resolution. 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 optimize
the null point being checked.
23 Set the TX MODULATION SOURCE to EXTERNAL. Set the synthesizer to the
jitter frequency being tested and set the level to achieve the null being tested.
3-96
and set for PDH Jitter, Short Term. (Timing Control, 1