Nokia 6600 - Page 33

NHL-10
RF Troubleshooting CCS Technical Documentation
ISSUE 2 01/2004 COMPANY CONFIDENTIAL 33
Copyright © 2003 Nokia. All Rights Reserved.
The spectrum analyzer screen should now look similar to that of the figure below (GSM900
case).
Figure 4: Spectrum analyzer screen shot when performing IQ tuning
The purpose of this tuning is to reduce the frequency components at marker 2 (carrier leakage)
and marker 3 (+67kHz / upper sideband) as much as possible. Adjust the TXI DC Offset and
the TXQ DC Offset buttons in the TX IQ Tuning window so that the carrier level (marker 2)
reaches a minimum. After this adjustment, the carrier (marker 2) should be at least 40dB below
the lower side band (marker 1).
Next, use the Amplitude difference and the Phase difference buttons in the TX IQ Tuning
window to adjust the upper side band (marker 3) to a minimum. Now, marker 3 should also be
at least 40dB below marker 1.
At this point, the spectrum analyzer screen should look similar to that of the figure below.
Ref Lvl
35 dBm
Ref Lvl
35 dBm
RBW 3 kHz
VBW 3 kHz
SWT 3 s
RF Att 30 dB
30 kHz/Center 897.4 MHz Span 300 kHz
27.5 dB Offset
A
1M
A
Unit dBm
-60
-50
-40
-30
-20
-10
0
10
20
30
-6
5
3
5
1
2
3
Marker 1 [T1]
33.35 dBm
897.33229000 MHz
1 [T1] 33.35 dBm
897.33229000 MHz
2 [T1] -6.76 dBm
897.40000000 MHz
3 [T1] -10.74 dBm
897.46771000 MHz
Date: 14.JAN.2002 13:11:55