User Guide

PAMS
Technical Documentation
WinTesla User Guide
NHD–4
Page 62
Original 11/97
Manual Verification
Spurious emissions of the CDMA transmitter can be read manual using a
spectrum analyzer. To do so perform the following steps:
1. Feed the RF output of the phone into the spectrum analyzer.
2. Set the CDMA TX output power to maximum using the manual TX gain
controls. The Service Software also rails the CDMA TX to maximum for
the CDMA TX Quick Test.
3. Set the Resolution Bandwidth of the spectrum analyzer to 30 kHz. Use
the averaging functionality of the spectrum analyzer to get readings of
better precision.
4. Set a marker + 30 kHz off the center frequency of the transmit signal.
5. Set another marker + 900 kHz off the center frequency.
6. The delta between the two markers should be at least 26 dB.
7. Repeat this test with markers –30 kHz and –900 kHz off the center
frequency.
The resultant value reported from the automated tester is the power
difference (delta) in dB between the 30 kHz and 900 kHz frequency offset
positions, as described above
Troubleshooting
The CDMA transmitter must be functioning properly to correctly perform
this test. The maximum power level of the CDMA TX must be correct,
approximately 24 dBm. The operation of the CDAGCT IC (N100) and the
AT–I09 attenuator IC (V106) greatly influence the results of this test.
Should this test fail, it is suggested that their health and functionality be
inspected. The Service Manual Transmitter Troubleshooting section and
Functional Description will provide information and tests for the transmitter
chain.
LNA Gain Calibration
Definition of Test
This operation determines the gain differential of the receiver system with
the LNA on and off. The CDMA receiver system is then calibrated
accordingly. To do this a constant level CW tone is fed into the CDMA
receiver. The LNA is turned on and the received signal strength to the
CDSB ASIC (D704) is read and stored. This is the also known as the
RxCtr value. With the same input signal the LNA is then turned off and
the RxCtr is read again. The dB power difference between the two RxCtr
values is equivalent to the gain that the LNA provides.