User Guide

PAMS
Technical Documentation
WinTesla User Guide
NHD–4
Page 37
Original 11/97
RX Offset Tuning – (RX)
The purpose of this tuning operation is to calibrate the center the dynamic
range of the RxDAC to correspond to the midpoint of the dynamic range of
the CDMA receiver.
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 designation on the name of this tuning
implies that the CDMA receiver is functioning when this tuning occurs, but
not the transmitter. A separate tuning must occur when the transmitter is
on as well, hence the reason for the RX_OFFSET (RX/TX) tuning found
above.
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 Rx”
– Adjust the Rx Offset Rx 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.