LG U8210 Service Manual page 175

7. CALIBRATION
B. GSM Freq. Comp. Calibration
- Purpose
This item contains the change in Tx power of 7 ARFCN (Absolute Radio Frequency Channel Number)
relative to a reference ARFCN (channel 49).
NOTE 7 ARFCN + 1 ref channel = 8 channels.
- Procedure Proposal
1. Load the highest DCS power as defined in the standard.
2. Measure frequency response of the phone across 8 different ARFCN.
3. The data structure for all Tx frequency-compensated NV items are laid out as in the following
example.
NV_GSM_TX_FREQ_COMP
-8,-2,0,3,5,5,-7,-6
NOTE The first data index will correspond to channel index 0 and so on until the last index is reached
for all channels. The data point for the reference channel will always be 0.
C. GSM RX Gain Range Calibration
- Purpose
This item specifies the RX gain from the antenna to the MSM for 8 frequencies in the GSM band.
- Procedure Proposal
1. Command the signal generator to output a signal level, Pin (recommended value is -65 dBm) at the
phone antenna port.
2. Command the signal generator to one of the 8 specified channels plus an offset of 33 kHz.
3. Command the phone to one of the 8 specified channels.
4. Command the phone to set up gain range 0 ( 1, 2, or 3 ).
5. Command the phone to retrieve RSSI. Let's call this value Xrssi.
6. Calculate and record (in 1/16 dB units) the absolute gain from antenna to MDSP using the following
equation.
NV_GSM_RX_GAIN_RANGE_1_FREQ_COMP = 16*( 10Log(xrssi) - Pin)
7. Repeat steps above for the next ARFCN in the NV_GSM_CAL_ARFCN item.
8. The data structure for all Rx frequency-compensated NV items are laid out as in the following
example.
NV_GSM_RX_GAIN_RANGE_1_FREQ_COMP
2036,2039,2035,2039,2036,2026,2031,2037
NOTE The first data index will correspond to channel index 0 and so on until the last index is reached
for all channels. Rx frequency-compensated NV items are absolute measurement, not relative
measurement like Tx NV items.
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