u-blox M8 Series, Руководство по интеграции оборудования

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Out-band interference
Out-band interference is caused by signal frequencies that are different from the GNSS carrier (see
Figure 17). The main sources are wireless communication systems such as GSM, CDMA, WCDMA,
Wi-Fi, BT.
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 17: 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 4) into the antenna input line
to the GNSS receiver (see Figure 18).
Figure 18: Measures against out-band interference
☞
For design-in recommendations in combination to Cellular operation see the Appendix.
☞
See the GPS Implementation and Aiding Features in u-blox wireless modules [10].