LG U8138 Service Manual page 210

- Procedure Proposal
1. Put the ME in switched TX mode on mid channel in frequency interval 11 for EGSM
(with random modulation).
2. Measure the RMS phase error at the RF connector.
3. Tune the phase detector current (IPHD)until the phase error is minimized.If two IPHD settings gave
the same RMS,choose the lowest value.Measure 10 bursts for each value.
4. Calculate and store the IPHD values in GDFS
(GD_IPHD_8Temperature_and_24Channel_Compensation_Band)
5. The offsets in the table are steps in the IPHD Table 8.2 and all offsets refer to the calibrated value
(Trim) at mid channel in room temperature.
0 1 2 3 4
0 -2 -2 -2 -2 -1 -1 -1 -1 -1
1 -2 -2 -2 -2 -1 -1 -1 -1 -1
2 -2 -2 -2 -2 -1 -1 -1 -1 -1
3 -2 -2 -2 -2 -1 -1 -1 -1 -1
4 -2 -2 -2 -2 -1 -1 -1 -1 -1
5 -2 -2 -2 -2 -1 -1 -1 -1 -1
6 -2 -2 -2 -2 -1 -1 -1 -1 -1
7 -2 -2 -2 -2 -1 -1 -1 -1 -1
E. VCXO Calibration
- Purpose
This procedure aims to calibrate the value of DAC3 to establish a VCXO-frequency that is sufficiently
close to 13 MHz at room temperature.It also ensures that the VCXO tuning range is sufficient,and that
the temperature compensation table for VCXO is completed accordingly.
Note:The frequencies in this section are related to the 13 MHz VCXO-frequency.
Depending on the calibration procedure,the 13 MHz VCXO frequency can be acquired by first
measuring an EGSM,DCS,or W-CDMA RF frequency at the antenna and then translating the
measured frequency to the 13 MHz VCXO frequency.
- Procedure Proposal
1. Put the ME in switched low power TX mode with a modulated carrier on a mid channel.
Use the calibrated value of the cap array and phase detector current.
2. Tune DAC3 in AB 2000 (VCXOCONT)to end and mid values,and check tuning range.
Frequency Interval
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
Table 8-2. IPHD Compensation for EGSM Band
- 211 -
0 0 0 1 1 1
0 0 0 1 1 1
0 0 0 1 1 1
0 0 0 1 1 1
0 0 0 1 1 1
0 0 0 1 1 1
0 0 0 1 1 1
0 0 0 1 1 1
8. CALIBRATION
1 1 1 2 2 2
1 1 1 2 2 2
1 1 1 2 2 2
1 1 1 2 2 2
1 1 1 2 2 2
1 1 1 2 2 2
1 1 1 2 2 2
1 1 1 2 2 2
2
2
2
2
2
2
2
2