SE873 Family Product User Guide
Product Features
1VV0301216
Rev.4
Page 20 of 69
2018-08-24
Jamming Rejection – Continuous Wave (CW) Jamming
Mitigation
Continuous Wave (CW) jamming mitigation improves performance in a system that is affected by
these predictable jamming signals:
•
Stable jamming signals generated by your system implementation, such as harmonics of
digital clocks and logic switching
•
Predictable jamming signals in the RF environment (e.g. from collocated transmitters)
When this feature is activated, the process for jamming mitigation is:
1. Detect jamming signals above the noise floor.
2. Isolate and filter frequencies containing jamming signals.
The GNSS signal is constantly monitored for CW jammers and up to eight are detected and
cancelled in each band without any operator intervention.
GPS, GLONASS, and BDS band cancellers are activated and reported using OSP
MID 92
. This
feature is useful both in the design stage and during the production stage for uncovering issues
related to unexpected jamming. Use OSP
MID 220,1
to configure this feature.
Elevation Mask Angle
The default elevation mask angle is 5° which can be changed using OSP
MID 139
.
5 Hz and 10 Hz Navigation
When this feature is enabled, the receiver starts in 1 Hz mode and continues until it achieves an
over-determined fix with 5 or more satellites. It then computes and outputs solutions 5 or 10 times
per second. Each computation uses fewer, but more frequent satellite observations. In most
situations this gives a better response to vehicle velocity and course changes but might cause
slightly more erratic performance in stationary or low-dynamic situations.
The receiver also attempts to send out 5 or 10 times as many messages per second. The data
rate may need to be increased or the set of scheduled messages be reduced to avoid overloading
the available bandwidth.
For NMEA protocol, with default messages set on (GGA, GSA and RMC output once per cycle
and GSV output once every 5 cycles) output is nearly 1300 characters per second at 5 Hz.
Including start and stop bits, at least 19200 bps is required to avoid running out of bandwidth.
For multi-constellation output, one GNGNS and one GNGSA would be added to each report cycle,
and three GNGSV sentences every 5
th
cycle, requiring a minimum of 38,400 bps data rate at 5
Hz. For OSP protocol, CSR recommends a minimum data rate of 115,200 bps.
To enable 5 or 10 Hz Navigation, use a
$PSRF103
command or an OSP
MID 136
command with
bit 2 of the pos_mode_enable field set to 1.
1PPS
The module provides a 1PPS timing pulse. See section
Summary of Contents for SE873 Series
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