TEST AND MEASUREMENT
MCUK000601C8 Section 6 Issue 1
Service Manual – 47 – Revision 0
17. Repeat steps6 to 16 for both low/ bottom and high/ top channels.
18. Repeat steps6 to 16 for GSM1800 on the following channels with the SET AGC1 field set to 51dB:
6.6.4. I and Q Values
NOTE: With the I, Qch adjustment procedures, the transmitter must be set to Power Level 5 (this represents the worst
case of non-linearity) so care must be taken that the spectrum analyser used can accept a signal input of
33dBm. If not, an appropriate attenuator must be used.
I, Q ch Offsets
Spectrum analyser setup:
Centre frequency = 902.4MHz
RBW = 10kHz
VBW = 10kHz
span = 1MHz
sweep time = 2sec
1. Set the Channel box to channel62 at power level 5, nominal burst modulated with all 1’s, as shown below:
Figure 6.23: Channel box setup
2. On the spectrum analyser, measure the image leak ratio.
Image leak ratio is the measured ratio of peak power and the power at 135kHz below peak frequency.
Example:
Peak power= 33dB
Power at 135kHz below peak power= -9dBm
Image leakage ratio = 33dBm - (-9dBm)= 42dBm
Channel GSM900
Low / bottom 1
Mid 60
High/ top 111
Channel GSM1800
Bottom / low 512
Mid 650
High / top 885
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