CSI Wireless Seres, Reference Manual

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Seres Reference Manual
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3.2.2 SBAS Performance
The performance of the SBAS receiver is described in terms of lock icon
and a bit error rate (BER). SBAS requires a line of sight to the SBAS
satellites in order to acquire the signal.
The BER number indicates the number of unsuccessfully decoded symbols
in a moving window of 2048 symbols. Due to the use of forward error
correction algorithms, one symbol is composed of two bits. The BER value
for both SBAS receiver channels is available in the RD1 NMEA data
message described in detail in Chapter 6.
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
Seres 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
model and the ionospheric SBAS map. To minimize the impact
of this issue on your use of the Seres, we suggest that you wait up
to five minutes before using the Seres or issue the
$JQUERY,GUIDE<CR><LF> message to ‘ask’ the Seres if it feels
accuracy will be sufficient for operation.