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
118
138
RSSI 7
141...143
131
151
136...139
128
148
RSSI 8
151...153
141
161
146...149
138
158
