u-blox NEO-M8P-2, Hardware Integration Manual

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NEO-M8P - Hardware Integration Manual
UBX-15028081 - R05 Early Production Information
Product handling
Page 23 of 27
Measures against in-band interference 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 interference
Out-band interference is caused by signal frequencies that are different from the GNSS carrier (see Figure 15 ). 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 15: Out-band interference signals
Measures against out-band interference include maintaining a good grounding concept in the design and adding
a SAW or band pass ceramic filter (as recommend in
section 3) into the antenna input line to the GNSS receiver
(see Figure 16 ).
Figure 16: Measures against out-band interference
For design-in recommendations in combination to Cellular operation see Appendix
See the GPS Implementation and Aiding Features in u-blox wireless modules [5]