User Guide

PAMS
Technical Documentation
WinTesla User Guide
NHD–4
Page 36
Original 11/97
CDMA Tuning
RX Offset Tuning – (RX/TX)
The purpose of this tuning operation is to calibrate the mid point of the
CDMA Receiver’s dynamic range.
This tuning is needed if the duplexor, CDGACR (N1) or BBFIL (N2) is
changed.
Definition of Tuning
The purpose of this tuning is to center the dynamic range of the RxDac to
correspond to the midpoint of the dynamic range of the CDMA receiver. A
–65 dBm 881.62 MHz signal is fed into the phone. –65 dBm is the
midpoint of the –25 to –105 dynamic range of the CDMA receiver. The
RX_OFFSET PDM is adjusted until the RxDac is at its midpoint of
approximately 200H. The RX/TX designation on the name of this tuning
implies that both the receiver and transmitter are functioning when this
tuning occurs. A separate tuning must occur when the transmitter is not
on, hence the reason for the RX_OFFSET (RX) tuning.
TX Offset calibration steps & equipment:
– Using the JBS–7 service jig, replace the standard battery of the phone
with the dummy battery BTS–4.
– Apply +6.0 V to dummy battery.
– Connect the modulation (or spectrum) analyzer to antenna connector.
– Select ” Tuning – Rx Gain Offset”
– Adjust the Rx Offset Value with arrow or PgUp/PgDn –keys until the
current RxDAC register value is with the target limits.
– Press <save & exit> to store value to EEPROM or <cancel> to exit
without saving.