User's Manual

Test Set Calibration – continued
PRELIMINARY
08/01/2001
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1X SCt4812ET Lite BTS Optimization/ATP
Calibrating RX Cables Using a
Signal Generator and Spectrum
Analyzer
Follow the procedure in Table 3-28 to calibrate the RX cables using the
signal generator and spectrum analyzer. Refer to Figure 3-20, if required.
Table 3-28: Calibrating RX Cables Using a Signal Generator and Spectrum Analyzer
Step Action
1 Connect a short test cable to the spectrum analyzer and connect the other end to the Signal Generator.
2 Set signal generator to –10 dBm at the customer’s RX frequency of 824.7–848.31 MHz for North
American cellular or 1850–1910 MHz band for North American PCS.
3 Use spectrum analyzer to measure signal generator output (see Figure 3-20, “A”) and record the value
for “A”.
4 Connect the test setup, as shown in the lower portion of the diagram, to measure the output at the
customer’s RX frequency (824.7–848.31 MHz for North American cellular or 1850–1910 MHz band
for North American PCS). Record the value at point ‘‘B”.
* IMPORTANT
When preparing to calibrate a BTS with duplexed TX and RX the cable calibration setup must include
the 30 dB directional coupler and 20 dB in–line attenuator as in the TX cable calibration shown in
Figure 3-19.
5 Calibration factor = A – B
Example: Cal = –12 dBm – (–14 dBm) = 2 dB
NOTE
The short test cable is used for test equipment setup calibration only. It is not part of the final test
setup. After calibration is completed, do not re-arrange any cables. Use the equipment setup, as is, to
ensure test procedures use the correct calibration factor.
Figure 3-20: Calibrating Test Equipment Setup for RX ATP Test
(Using Signal Generator and Spectrum Analyzer)
Spectrum
Analyzer
Signal
Generator
A
B
Spectrum
Analyzer
SHORT
TEST
CABLE
CONNECTION TO THE OUTPUT
PORT DURING RX MEASUREMENTS
Signal
Generator
BULLET
CONNECTOR
LONG
CABLE 2
SHORT TEST
CABLE
CONNECTION TO THE RX PORTS
DURING RX MEASUREMENTS.
IMPORTANT: IF BTS RX/TX SIGNALS ARE
DUPLEXED, THE RX TEST CABLE CONNECTS
TO THE DUPLEXED ANTENNA GROUP AND
MUST USE/BE CALIBRATED WITH THE 30 DB
DIRECTIONAL COUPLER AND 20 DB IN–LINE
ATTENUATOR. SEE FIGURE 3-19.
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