WM_PRJ_Q2501_PTS_002
- 001
March
2004
confidential ©
Page:
57 / 79
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even more compared to the GSM antenna, the GPS deals with very low
signals. Consequently, the antenna must be placed far from wide band
jammers like micro-controllers, RAM, DC-DC Converter.
One main source of GPS jamming is the GSM/GPRS transmission (especially
when using DCS1800 band that is only at 135 MHz from GPS signals):
Figure 34: GPS reception jammed by GSM/GPRS transmission
Even if the Q2501 module has been designed to minimize the influence of
GSM/GPRS on the GPS performance, user must pay special attention to the
GSM & GPS antenna proximity. As a rule of thumb, the level “seen” by the
GPS antenna must not exceed –10 dBm
.
Practically speaking, it is advised to have a minimum distance of 1 meter
between GPS & GSM antennas.
If Combo antenna is used (GSM & DCS antennas are gathered in the same
mechanic), the GPS part must use notch filters prior the LNA in order not to
saturate it. This point has to be discussed with the antenna designer.
Fortunately, once the GPS is synchronized (it has performed a location), it is
robust against jamming.
Summary of Contents for WISMO Quik Q2501
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