User Manual
Test Set Calibration – continued
Jan 2002
3-77
SC4812ET BTS Optimization/ATP — CDMA LMF
Calibrating Test Equipment
The calibrate test equipment function zeros the power measurement level
of the test equipment item that is to be used for TX calibration and audit.
If both a power meter and an analyzer are connected, only the power
meter is zeroed.
Calibrate Test Equipment from the Util menu list is used to calibrate
test equipment item before being used for testing. The test equipment
must be selected before beginning calibration. Follow the procedure in
Table 3-32 to calibrate the test equipment.
Table 3-32: Test Equipment Calibration
Step Action
1 From the Util menu, select Calibrate Test Equipment. A Directions window is displayed. Follow
the instructions provided.
2 Follow the direction provided.
3 Click on Continue to close the Directions window. A status window is displayed.
4 Click on OK to close the status report window.
Calibrating Cables
The cable calibration function is used to measure the loss (in dB) for the
TX and RX cables that are to be used for testing. A CDMA analyzer is
used to measure the loss of each cable configuration (TX cable
configuration and RX cable configuration). The cable calibration
consists of the following procedures.
Measure the loss of a short cable. This is done to compensate for any
measurement error of the analyzer. The short cable, which is used only
for the calibration process, is used in series with both the TX and RX
cable configuration when they are measured. The measured loss of the
short cable is deducted from the measured loss of the TX and RX
cable configuration to determine the actual loss of the TX and RX
cable configurations. This deduction is done so any error in the
analyzer measurement will be adjusted out of both the TX and RX
measurements.
Measure the short cable plus the RX cable configuration loss is
measured. The RX cable configuration normally consists only of a
coax cable with type–N connectors that is long enough to reach from
the BTS RX port the test equipment.
Measure the short cable plus the TX cable configuration loss is
measured. The TX cable configuration normally consists of two coax
cables with type–N connectors and a directional coupler, a load, and
an additional attenuator if required by the BTS type. The total loss of
the path loss of the TX cable configuration must be as required for the
BTS (normally 30 or 50 dB). The Motorola Cybertest analyzer is
different in that the required attenuation/load is built into the test set
so the TX cable configuration consists only of the required length
coax cable.
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