LEA-M8F - Hardware Integration Manual
UBX-14000034 - R03
Early Production
Information
Product
handling
Page 27 of 30
Figure 20: In-band jamming sources
Measures against in-band jamming include:
•
Maintaining a good grounding concept in the design
•
Shielding
•
Layout optimization
•
Filtering
•
Placement of the GNSS antenna
•
Adding a CDMA, GSM, WCDMA band pass filter before handset antenna
Out-band jamming
Out-band jamming is caused by signal frequencies that are different from the GNSS carrier (see
Figure 21). The
main sources are wireless communication systems such as GSM, CDMA, WCDMA, Wi-Fi, 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 21: Out-band jamming signals
Measures against out-band jamming include maintaining a good grounding concept in the design and adding a
SAW or band pass ceramic filter (as recommend in
Section 4) into the antenna input line to the GNSS receiver
(see
Figure 22: Measures against in-band jamming
