LG T5100, Service Manual, Page: 116 / 136

7. Service and Calibration
- 117 -
7.2.3 Equipment Setup
7.2.4 Calibration steps
A. RX Calibration
In order for the RSSI measurements to be within the GSM specifications, some calibration is
necessary. Also, due to AGC implementation, some AGC specific constants need calibration. In total,
three calibrations are required per receive band, AGC calibration, channel compensation and
temperature compensation. Of these, temperature compensation is not needed in replacement of the
circuit. In AGC calibration the reference power fed into the phone via permanent antenna connector is
-74dBm. In channel compensation, the channel numbers in Rx band are;
E-GSM band : 0, 40, 124, 975, and 1023.
DCS band : 512, 574, 636, 700, 760, 822 and 885.
Procedure
a) Initialize phone by clicking Initialize button.
b) Set the GSM test equipment CW mode and BCH and TCH of GSM test equipment ‘0’, same with
phone.
c) Set the power of GSM test equipment ‘-74dBm’.
d) Click the PM Start button, then the value, received power by phone, is displayed in PM
measurement window at service software.
e) Change the BCH and TCH of phone by clicking the Number button and set the channel (BCH &
TCH) of equipment to be same.
Mobile Switch Cable
Power Supply
GPIB
Cable
PC
Battery Simulator
Jig
TA
GSM Test Set(8960)
GPIB Cable
Figure 7-1 Calibration Equipment List