LEA-5, NEO-5, TIM-5H - Hardware Integration Manual
GPS.G5-MS5-09027-A2
Released
Design-in
Page 49 of 68
1525
1550
1625
GPS input filter
characteristics
1575
1600
0
-110
Jammin
g signal
1525
1550
1625
Frequency [MHz]
Power [dBm]
GPS input filter
characteristics
1575
1600
0
Jamming
signal
GPS
signals
GPS Carrier
1575.4 MHz
Figure 41: In-band jamming signals
u-blox
5 LNA
u-
blox GPS
receiver
CPU
data bus
Figure 42: In-band jamming sources
Measures against in-band jamming include:
Maintaining a good grounding concept in the design
Shielding
Layout op emperature iltering
Placement of the GPS antenna
Adding a CDMA, GSM, WCDMA bandbass filter before handset antenna
2.7.7.4
Out-band jamming
Out-band jamming is caused by signal f
requencies that are different from the GPS carrier (see
). The main
sources are wireless communication systems such as GSM, CDMA, WCDMA, WiFi, 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 43: Out-band jamming signals
Measures against out-band jamming include maintaining a good grounding concept in the design and adding a
SAW or bandpass ceramic filter (as recommend in
Section 2.7.5
) into the antenna input line to the GPS receiver
(see Figure 44).
