LEA-M8S / LEA-M8T - Hardware Integration Manual
UBX-13003140 - R07
Production Information
Product handling
Page 27 of 31
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 20).
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 20: 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 21).
Figure 21: Measures against in-band interference
