SX BLUE GPS iSXblue II+ GNSSTM, Руководство пользователя

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SXblue Series User Manual 48
Keeping in mind that this horizontal performance specification is a real world but
ideal scenario test, obstruction of satellites, multipath signals from reflective
objects, and operating with poor corrections will detract from the receiver’s ability
to provide accurate reliable positions. Sub meter differential performance can also
be compromised if the SXblue receiver is using SBAS in a region without sufficient
ionospheric map coverage. If external corrections are used, the distance between
the remote and reference station antennas can affect performance.
Since the SXblue receiver will be used sometimes in harsh conditions, blockage
of the line of sight to SBAS satellites is often inevitable. The COAST technology
provides solace from obstruction of SBAS or other code-phase differential
correction services for up to about 40 minutes, depending on the amount of
tolerable performance drift.
The estimated positioning accuracy is accessible through the use of NMEA 0183
command responses (GST NMEA data message) as described in the Technical
Reference Manual. As the receiver is not able to determine accuracy with respect
to a known location in real time (this is traditionally performed in post-mission
analysis), the accuracy numbers are relative in nature and are approximates.
2.1.3 Update Rates
By default, the SXblue receiver is supplied with a 1 Hz update rate. Higher update
rate option can be purchased via your dealer and a code will be used to unlock the
feature. Other available update rates are 10 Hz and 20Hz. Carrier phase output
is standard on the SXblue receiver.
The update rate of each NMEA and binary message of the SXblue receiver can be
set independently with a maximum that is dependent upon the message type.
Some messages have a 1 Hz maximum, for example, while others are up to 20
Hz.
Higher update rates are valuable for applications where higher speeds are present
(such as aviation, UAVs or racing cars) or more frequent updates are required for
manual navigational tasks, such as Agricultural Guidance.
2.2 SBAS
The following sections describe the general operation and performance monitoring
of the SBAS demodulator within the SXblue receiver. See Appendix B for more
information on SBAS currently (at time of print) available in the world.