Calibration Steps - LG F1200 Service Manual

12. SERVICE AND CALIBRATION

12.2.3 Calibration steps

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;
A. RX Calibration
E-GSM band : 0, 40, 124, 975, and 1023.
DCS band : 512, 574, 636, 700, 760, 822 and 885.
PCS band : 512, 574,636,700,760and 810.
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.
f) Click the PM Start button.
g) Repeat above procedure until the displayed number in Power Measurement window is 12.
h) Click the Calculate button, then the service software calculate the channel compensation
parameters.
i) Saving updated calibration data into phone by clicking Calib Saving button.
<NOTE>
If the calibration does not done for all channels, 5 channels for EGSM900 and 7 channels for
DCS1800,PCS1900, the service software reports, "Please execute after measuring the PM".
B. TX Calibration
In order for the Tx power to be within the GSM specifications for each Tx level, some calibration
is necessary. In total, four calibrations are required per transmit band, power calibration, channel
compensation, temperature compensation and low voltage compensation. Of these, temperature
compensation and low voltage compensation are not needed in replacement of the circuit and
channel compensation is not needed because the transmit power is in GSM specification with
enough margin In power compensation, the channel numbers used in Tx band are;
E-GSM band : 62.
DCS band : 699.
PCS band : 689
And the target powers in dBm for each power level are;
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