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LEA-6 / NEO-6 - Hardware Integration Manual
GPS.G6-HW-09007-A
Preliminary
Product handling
Page 45 of 62
u-blox
5 LNA
u-
blox GPS
receiver
CPU
data bus
Figure 37: In-band jamming sources
Measures against in-band jamming include:
•
Maintaining a good grounding concept in the design
•
Shielding
•
Layout optimisation
•
Filtering
•
Placement of the GPS antenna
•
Adding a CDMA, GSM, WCDMA bandpass filter before handset antenna
3.3.8.4
Out-band jamming
Out-band jamming is caused by signal f
requencies that are different from the GPS carrier (see
Figure 38
). The main
sources are wireless communication systems such as GSM, CDMA, WCDMA, WiFi, BT, etc..
0
500
1000
1500
2000
GPS input filter
characteristics
0
-110
0
500
1500
2000
Frequency [MHz]
GSM
900
GSM
1800
GSM
1900
Power [dBm]
GPS input filter
characteristics
GPS
1575
0
-110
GPS
signals
GSM
950
Figure 38: Out-band jamming signals
Measures against out-band jamming include maintaining a good grounding concept in the design and adding a
SAW or bandpass ceramic filter (as recommend in
Section 3.3.6
) into the antenna input line to the GPS receiver
(see Figure 39).
u-blox
5 LNA
u-
blox GPS
receiver
CDMA, GSM,
WCDMA, etc.
Figure 39: Measures against in-band jamming
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