u-blox NEO-7M-0 - Page 50

MAX-7 / NEO-7 / LEA-7 - Hardware Integration Manual
GPS.G7-HW-11006-1 Product handling
Page 50 of 55
5.3.7.4 Out-band jamming
Out-band jamming is caused by signal frequencies that are different from the GPS carrier (see Figure 40). 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 40: 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 5.3.5) into the antenna input line to the GPS/GNSS
receiver (see Figure 41).
Figure 41: Measures against in-band jamming