u-blox AMY-5M Hardware Manual page 37

Pow er [dBm]
Interference
signal
0 0
-110
1525 1525 1550 1550
Figure 25: In-band interference signals
CPU
data bus
Figure 26: In-band interference sources
Measures against in-band interference include:
Maintaining a good grounding concept in the design
Shielding
Layout optimisation
Filtering
Placement of the GPS antenna
Adding a CDMA, GSM, WCDMA bandbass filter before handset antenna
2.11.7.4 Out-band interference
Out-band interference is caused by signal f
sources are wireless communication systems such as GSM, CDMA, WCDMA, WiFi, BT, etc..
Pow er [dBm]
0 0
GPS input filter GPS input filter
characteristics characteristics
-110 -110
0 0 500 500
Figure 27: Out-band interference signals
Measures against out-band interference include maintaining a good grounding concept in the design and
adding a SAW or bandpass ceramic filter (as recommend in Section 2.11.5) into the antenna input line to the
GPS receiver (see Figure 28).
GPS.G5-MS5-08207-A3
GPS Carrier
1575.4 M Hz
GPS
signals
Jammin
g signal
GPS input filter GPS input filter
characteristics characteristics
1575 1575 1600 1600
requencies that are different from the GPS carrier (see
GPS
GSM
GSM
signals
950
900
1000 1500 1500
AMY-5M - Hardware Integration Manual
Frequency [M Hz]
1625 1625
u-blox
blox GPS
u-
receiver
5 LNA
GPS GSM GSM
1575 1800 1900
2000 2000
Preliminary
Figure 27
Frequency [M Hz]
). The main
Design-in
Page 37 of 54