Nokia 9000i Service Manual page 188

RAE/RAK–1N
Service Software
3.2.6 – Noise Sensitivity
This function is used for making Signal to Noise measurement.
The following automatic selections are made when this tuning function is
activated:
– Active Unit = RX
– Operation mode = Continuous
– AGC = 93 dB in GSM ; 81dB in PCN
When this selection is made the next window is displayed.
Clipping distance is the difference to the signal clipping value. SNR is
measured in the A/D converter.
Clipping distance = clipping level (66) – signal value + comp_factor1 SNR
= signal value – noise value + comp_factor1
Sensitivity = –90 dBm + 8 dB + comp_factor2 – SNR
The last value on the display is signal power difference between I and Q
branch. The numbers are shown in 0.1 dB accuracy. The error messages,
"OUT OF RANGE", are shown only if the SNR and/or amplitude difference
values are not acceptable.
(SNR <= 18 dB + comp_factor2 – 0.5 dB(=accuracy) ;
Sensitivity >= –100 dBm + 0.5 dB ; |Si – Sq| > 1dB).
When <F2> or <F3> is pressed, the RX I and Q burst data is asked for
and "SIGNAL MEASURING" or "NOISE MEASURING" is displayed. The
power level value should be –90 dBm during signal measurement.
Only the <Esc> key is accepted during measurement. <Esc> breaks the
measurement routine in the PC and returns the program to the state
before <F2> or <F3> was pressed. Normally <Esc> is not needed.
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