13
July 6, 2010
AN1559.0
GPS aggressor cancellation. Once the “GPS Optimization
Setup (Static Coupling Channel)” is ready, use the
software provided to configure the device as previously
described.
1. Select the GPS frequency band of operation.
2. Start with the lowest gain setting.
3. Then adjust the I and Q (or gain and phase) until the
maximum attenuation is achieved at the desired
frequency.
Figure 13 is an example of the type of cancellation that
should be achieved when the I and Q values have been
optimized.
Once the cancellation has been optimized, record the I
and Q values for the optimization of the setup used.
ATTENUATOR PAD
TO SET COUPLING LOSS
GPS AGGRESSOR
NETWORK
ANALYZER
QHX220
CANCELLATION
NODE
POWER
SPLITTER
PORT 1
PORT 2
POWER
SPLITTER
50
Ω
TERMINATION
PATH
FIGURE 12. GPS OPTIMIZATION SETUP DIAGRAM
FIGURE 13. EXAMPLE OF OPTIMUM CANCELLATION (GPS)
-80
-70
-60
-50
-40
-30
1400
1450
1500
1550
1600
1650
1700
FREQUENCY (MHz)
AFTER CANCELLATION
BEFORE CANCELLATION
GPS BAND
C
O
UP
LI
NG
CHA
N
N
E
L (dB)
Application Note 1559
