Egsm 900 Calibration Items - LG U8130 Service Manual

8.3.3 EGSM 900 Calibration Items

A. MOD-A(MD bit) Delay Calibration
- Pur pose
The procedure is designed to calibrate the timing alignment between the MODA-D signals and the
reference signal (13 MHz).It also ensures that the MOD signals have stable values when they are
clocked into the divider of the Phase-Locked Loop (PLL).
- Procedure Proposal
1. Set the ME to mid channel in the GSM TX band.
2. Set the delay setting in default mode,that is,no delay.
3. Wait approximately 300 us to 400 us to allow the PLL to lock.
4. Measure the RMS phase error.A threshold value of >20 deg indicates that the PLL is running in the
forbidden time region.
5. Save the RMS phase error result locally.
6. Step up the delay setting according to Table 8.1 below.
7. Repeat from step 4.
8. Choose delay setting that gives maximum distance to the consecutive field of corrupted RMS phase
error values in the vector.
9. Store delay setting both to the GD_RF_Mod_Delay and to the GD_DirMod_Mod_Delay.
10. Reset the radio.
Index
[0]
[1]
[2]
[3]
[4]
[5]
[6]
[7]
DIMC
0
0
0
0
1
1
1
1
Table 8-1. Delay Settings for the MOD-A
- 209 -
8. CALIBRATION
MD
00(0)
01(1)
10(2)
11(3)
00(0)
01(1)
10(2)
11(3)