Vector Sensor Reference Manual
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A lower BER indicates that data is being successfully decoded with fewer errors, providing more
consistent throughput. The bit error rate has a default, no-lock value of 500 or more. As the
receiver begins to successfully acquire the signal, it will result in a lower bit error rate. For best
operation, this value should be less than 150 and ideally less than 20.
Space-Based Augmentation Systems broadcast an ionospheric map on a periodic basis that may
take up to 5 minutes to receive upon startup. The Vector Sensor uses the GPS broadcast
ionospheric model until it has downloaded the SBAS map, which can result in lower performance
as compared to when the map has been downloaded. This will be the case for any GPS product
supporting SBAS services.
Caution - When the map has been downloaded, you may observe a position jump due
to the potential difference between the GPS ionospheric model and the ionospheric
SBAS map. To minimize the impact of this issue on your use of the Vector Sensor, we
may wish to wait up to five minutes before using the Vector Sensor or issue the
$JQUERY,GUIDE<CR><LF> message to ‘ask’ the Vector Sensor if it feels performance
will be sufficient for operation.
3.3
Beacon Operation
The following sections describe the general operation and performance monitoring of the SBX
beacon engine within the Vector Sensor.
3.3.1
Tune Modes
The internal beacon sensor may be operated in either Automatic or Manual beacon tune modes.
In Automatic Beacon Search (ABS) mode, the receiver will identify and tune to the station
providing the strongest DGPS signal. In Manual Tune mode, you specify the frequency to which
the receiver will tune. NMEA 0183 commands are used to modify the configuration of the beacon
sensor.
3.3.1.1
Automatic Beacon Search (ABS) Mode
The Vector Sensor’s internal beacon sensor operates in Automatic Beacon Search (ABS) mode by
default, selecting and tuning to the most appropriate beacon without operator intervention. The
beacon receiver uses its two independent beacon channels to identify and lock to DGPS beacons
without interrupting the continuous flow of RTCM data to the GPS receiver.
ABS mode is ideal for navigation applications over considerable areas, eliminating the need for
operator intervention when transitioning from one beacon coverage zone to another. The beacon
module may be manually tuned, however, this requires a NMEA command to be send to the
Vector Sensor as discussed in Chapter 6.
Note - We recommend that you leave the beacon receiver in the default ABS mode
unless your requirements mandate operating with a specific beacon.
3.3.1.2
ABS Global Beacon Search
When powered for the first time in ABS mode, the beacon sensor initiates a Global Search using,
