User's Manual Part 3

RFDS – Fault Isolation

Apr 2001

6-19

SC4812ET BTS Optimization/ATP — CDMA LMF

DRAFT

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 6-25: 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 (both

board and backplane) for damage.

7 Replace any boards that do not show green with known good boards one at a time in the following

order. Re–test after each is replaced.

– RFDS ASU board.

– RFDS Transceiver board.

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. Refer to the following

table for fault isolation procedures.

Table 6-26: RFDS Fault Isolation – All RX and TX paths fail

Step Action

1 Visually check the master RF converter board (both board and backplane) for damage.

2 Replace the RF converter board with a known good RF converter board.

3 Visually check RXCVR TSU (both board and backplane) for damage.

4 Replace the TSU with a known good TSU.