B-6
Appendix B - Fitting/Calibrating/Testing New Modules
Jitter Transmitter Module Calibration
If a new Jitter Transmitter Module has been fitted this will need to be calibrated
before it can be used, as all calibration data for this module is stored in a special
eeprom on the CPU Module.
Description
The Jitter Transmitter Calibration is semi-automatic and is performed by
using a special internal calibration routine and a Spectrum Analyzer. The HP
37717C TX PDH OUTPUT is connected to the Analyzer (via 75
Ω/50Ω]
Matching Pad) and set to the first calibration point in the routine. With the
Analyzer set to display the transmitted data spectrum, a Bessel Null should
be observed. The HP 37717C DAC output is adjusted using the calibration
routine to optimise this Bessell Null. This sets the transmitted jitter to
exactly 0.765UI. This process is repeated for all other Calibration points in
the routine.
Equipment
Pre-Adjustment Setup
Before carrying out Jitter Transmitter Calibration, you will need to perform the
following pre-adjustment setup.
1. Recall the HP 37717C Default Settings with the following key sequence;
2. Press , then . Select STORED SETTINGS
number [0]. Select ACTION [RECALL].
3. Couple the HP 37717C transmitter and Receiver with the following key sequence;
Press , then . Select TRANSMITTER &
RECEIVER [COUPLED]
Spectrum Analyser HP 8568B
75Ω/50Ω Matching Pad
HP 8568B
OTHER
STORED SETTINGS
OTHER
SETTINGS CONTROL
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