LG U8110 Service Manual page 221

8. CALIBRATION
F. RX LPF Bandwidth Calibration
- Purpose
This procedure calibrates the LPF bandwidth. The bandwidth of the channel filters will affect system
parameters as reception sensitivity and adjacent channel selectivity. The procedure also verifies that
the IF-filter is properly matched.
Figure 8-3. AGC Block Diagram (Parameter Ak, Output1, and Pref)
- Procedure Proposal
1. Feed a CW carrier at 2140 MHz with a power of -60dBm into the antenna connector.
2. Set UE in RX-mode on 10695ch.
3. Set the AGC_UL and AGC_LL to minimum. GLNA is forced to high gain mode.
4. Set RF 2110 LPQ and LPBW to 8, that is, LPQ=LPBW=8.
5. Get Ak (output2) from N slots. Calculate Average_Ak (Ak_IB) according to the equation below.
N should be as large as possible, with respect to time consumption.
6. Set UE on 10705ch and get Ak (output2). Calculate Average_Ak (Ak_LB) according to the Equation 1.
7. Calculate IF-filter symmetry using the following equation.
IF_SYM = Ak_IB - Ak_LB
8. Set UE on 10685ch and get Ak (output2). Calculate Ak (Ak_OB) according to the Equation 1.
9. Calculate selectivity level using following equation.
Ak_SE = Ak_OB – Ak_IB
10. If the requirement is not met, decrease LPBW and LPQ one step and repeat from 8.
11. Store the resulting LPBW and LPQ in GD_RF_RX_CONFIG_ID.
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