User's Manual Part 3

Power Delta Calibration
DRAFT
SCt4812T CDMA BTS Optimization/ATP
Mar 2001
I-2
Power Delta Calibration
Introduction
The In–service calibration procedure has several differences from a
normal calibration procedure. One of these is the use of a spectrum
analyzer instead of a power meter to measure power. Power meters are
broadband measurement devices and cannot be used to measure power
during In–service Calibration since other carriers are operating. A
spectrum analyzer can be used because it measures power at a given
frequency. However, measuring power using a spectrum analyzer is less
accurate than using a power meter. Therefore, you must compensate for
the difference (delta) between the power meter and the spectrum
analyzer.
HP8921A Power Delta
Calibration
Use the HP8921A Spectrum Analyzer to measure power during
In–Service Calibration for 800 MHz systems. After the offset value has
been calculated, add it to the TX cable loss value.
Follow the procedure in Table I-1 to perform the HP8921A Power Delta
Calibration procedure.
This procedure requires two HP8921As.
NOTE
Table I-1: HP8921A Power Delta Calibration Procedure
Step Action
* IMPORTANT
Perform this procedure after test equipment has been allowed to warm–up and stabilize for a minimum
of 60 minutes.
1 Connect a short RF cable between the HP8921A Duplex Out port and the HP437B power sensor (see
Figure I-1).
2 Set the HP8921A signal source as follows:
– Measure mode to CDMA Generator
– Frequency to the CDMA Calibration target frequency
– CW RF Path to IQ
– Output Port to Dupl
– Data Source to Random
– Amplitude to 0 dBm
3 Measure and record the power value reading on the HP437B Power Meter.
4 Record the Power Meter reading as result A ________________________.
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