Calibrating Cdma Channel Levels - HP 8924C Application Manual

Chapter 1, Calibrating the Test Set

Calibrating CDMA Channel Levels

Calibrating CDMA Channel Levels

AWGN
Analog I
Analog Q
Level Correction
Factors
26
Approximate time: 8 minutes
CDMA channel levels should be calibrated whenever any of the following events
occur:
• After a 30-minute warm-up period
• After firmware is upgraded
• If a 5° C change in ambient temperature occurs
The Test Set optimizes the level accuracy of CDMA code channels and the
AWGN (Additive White Gaussian Noise) generator by measuring the analog I/Q
signals on an internal DSP-based voltmeter. Level correction factors are generated
by a ROM-based program named PCB_CAL and are applied to gain control
DACs, which control the fine level adjustment in the amplitude scaling path.
Calibrated channel power provides accurate values for Eb/Nt, the ratio between
Traffic channel power and AWGN. It is critical that these levels remain accurate.
A level accuracy error of 0.8 dB could alter FER from 0.5% to 5%.
Gain Control
DAC
Diagnostic Mux
Σ
Σ
N:\mkt\MANUALS\HP8924C\APPMOD\BOOK\chapters\amcal.fb
To DSP
Voltmeter
I Output
Q Output