User's Manual

RFDS – Fault Isolation

PRELIMINARY

1X SCt4812ET Lite BTS Optimization/ATP

08/01/2001

6-26

Introduction

The RFDS is used to perform Pre–Calibration Verification and

Post-Calibration Audits which limit-check the RFDS-generate and

reported receive levels of every path from the RFDS through the

directional coupler coupled paths. In the event of test failure, refer to the

following tables.

All tests fail

Table 6-27: RFDS Fault Isolation – All tests fail

Step Action

1 Check the calibration equipment for proper operation by manually setting the signal generator output

attenuator to the lowest output power setting and connecting the output port to the spectrum analyzer

rf input port.

2 Set the signal generator output attenuator to –90 dBm, and switch on the rf output. Verify that the

spectrum analyzer can receive the signal, indicate the correct signal strength, (accounting for the cable

insertion loss), and the approximate frequency.

3 Visually inspect RF cabling. Make sure each directional coupler forward and reflected port connects to

the RFDS antenna select unit on the RFDS.

4 Check the wiring against the site documentation wiring diagram or the BTS Site Installation manual.

5 Verify RGLI and TSU have been downloaded.

6 Check to see that all RFDS boards show green on the front panel indicators. Visually check for

external damage.

7 If any boards that do not show green replace the RFDS with a known–good unit. Re–test after

replacement.

All RX and TX paths fail

If every receive or transmit path fails, the problem most likely lies with

the rf converter board or the transceiver board. Replace the RFDS with a

known–good unit and retest.

All tests fail on a single

antenna

If all path failures are on one antenna port, forward and/or reflected,

make the following checks.

Table 6-28: RFDS Fault Isolation – All tests fail on single antenna path

Step Action

1 Visually inspect the site interface cabinet internal cabling to the suspect directional coupler antenna

port.

2 Verify the forward and reflected ports connect to the correct RFDS antenna select unit positions on the

RFDS backplane. Refer to the installation manual for details.

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