User Guide

PAMS
Technical Documentation
NHD–4
Disassembly & Troubleshooting
Page 28
Original 11/97
CDMA TX Quick Checks with Service Software
The Service Software contains a Quick Check for the CDMA TX. From
the Test menu choose the CDMA Quick Test selection. A sub menu will
appear. Select the CDMA TX Quick Check. A window will appear
instructing you to feed the transmitter output into either a spectrum
analyzer or CDMA test box. Selecting the “TEST” soft button will turn on
the CDMA transmitter to its maximum power, approximately 24 dBm. If
not, then there is either some gain missing or a failure to provide the
appropriate input signal.
It should be noted that in CDMA operation, proper output power
measurements require that the bandwidth be taken into strict
consideration. CDMA output power readings must be performed across a
1.23 MHz band. A spectrum analyzer used for such measurements must
have the functionality to read band power. Otherwise, a CDMA signal
simply appears as an amplified noise floor, 1.23 MHz wide. For maximum
CDMA TX output power, the peak of this noise–like signal will be
approximately 10 dBm. CDMA test boxes have this capability built in.
Manual Output Power Control
The following two tests provide means to manually control the output
power of the NHD–4 transmitter in either the AMPS or CDMA modes.
AMPS TX Gain Control – Manual Control
The AMPS transmitter gain is controlled from the TXI_REF PDM. This
PDM has a manual control within the AMPS Quick Checks window of the
Service Software Test menu. With the phone in AMPS Troubleshooting
Mode the transmitter output power can be manipulated with this PDM
control. The table below details approximate PDM values, in decimal,
necessary to achieve corresponding power levels. These values will vary
from phone to phone.
AMPS TX
Output Power
(dBm)
TXI_REF PDM
decimal value
30 00
27 238
24 208
21 176
18 166
15 160
12 155
9 152
6 151