User Guide

CCS Technical Documentation
NSB-9
Issue 1 04/03 Copyright Nokia. All rights reserved.. Page 45
*) Tuning may return values between -6...37 but values between 0...31 are saved to phone
permanent memory. Values -6...0 are round up to 0 and values 31...37 are round down to
31.
RX Calibration
Description
Calibrates 26 MHz voltage controlled reference oscillator VCTCXO at the beginning of
GSM850 receiver gain (RSSI) tuning. AFC control voltage for VCTCXO is produced using
11-bits DA-converter inside UEM RF IC. AFC DAC value (AFC VALUE) which gives correct
VCTCXO output frequency is defined by measuring RX I/Q signal frequency and by adjust-
ing AFC to set correct frequency. AFC VALUE is used as an init value when phone has not
found a base station signal yet.
After correct AFC VALUE is found, AFC value is changed to different value. RX I/Q fre-
quency is measured again and AFC SLOPE (frequency change divided by AFC value
change) is calculated.
GSM850 and GSM1900 RX chains gain are tuned at middle channel.
Table 2: RX Calibration Limits
RX AM Suppression Calibration
Description
Calibrates GSM850 and GSM1900 RX mixer local signal DC-levels to achieve best rejec-
tion for AM modulated interferences. Calibration needs external AM modulated signal
applied to the phone. If tuning is successful, either LOP or LOM result in both branch (I
Band GSM850 GSM1900
Item Typical value
Low
limit
High
limit
Typical value
Low
limit
High
limit
AFC VALUE -300...0 -350 350 NA NA NA
AFC SLOPE 240...260 150 350 NA NA NA
RSSI 0 74...76 65 85 67...71 59 79
RSSI 1 84...86 75 95 77...81 69 89
RSSI 2 94...96 85 105 87...91 79 99
RSSI 3 101...103 91 111 96...99 88 108
RSSI 4 111...113 101 121 106...129 98 118
RSSI 5 121...123 111 131 116...119 108 128
RSSI 6 131...133 121 141 126...129 11 8 138
RSSI 7 141...143 131 151 136...139 128 148
RSSI 8 151...153 141 161 146...149 138 158