SC872-A
Product User Guide
Product Features
1VV0301202 Rev. 6
Page 16 of 53
2018-12-21
4 PRODUCT FEATURES
Multi-Constellation Navigation
GPS and GLONASS constellations are enabled by default. If BeiDou is enabled, GLONASS and
Galileo are disabled.
The user may enable or disable constellations via the
$PMTK353
command
Quasi-Zenith Satellite System (QZSS)
The satellites of the Japanese regional SBAS are in a highly inclined, elliptical geosynchronous
orbit, allowing continuous high-elevation coverage over Japan using only three satellites plus
one geostationary satellite. PRNs 193, 194, and 195 are supported. They provide ranging
signals for augmentation of the GPS system.
QZSS constellation usage is controlled by the
$PMTK352
command and is disabled by default.
NMEA reporting for QZSS may be enabled/disabled by the
$PMTK351
command.
Satellite-Based Augmentation System (SBAS)
The receiver is capable of using SBAS satellites as a source of differential corrections. These
systems (WAAS, EGNOS, GAGAN and MSAS) use geostationary satellites to transmit signals
similar to those of GPS in the same L1 band.
Enabling the SBAS feature limits the maximum fix rate to 5 Hz. Otherwise, the maximum is 10
Hz.
The module is enabled for SBAS by default, but can be disabled by command $
PTMK313
.
SBAS corrections are set by the $
PMTK301
command.
SBAS Corrections
The SBAS satellites transmit a set of differential corrections to their respective regions. The use
of SBAS corrections can improve positioning accuracy.
Assisted GPS (AGPS)
Assisted GPS (or Aided GPS) is a method by which information from a source other than
broadcast GPS signals is used to improve (i.e. reduce) TTFF.
The necessary ephemeris data is calculated either by the receiver itself (locally-generated
ephemeris), or a server (server-generated ephemeris) and is then stored in the module.
Locally-generated AGPS - Embedded Assist System (EASY)
Proprietary algorithms within the module perform GPS ephemeris prediction locally from stored
broadcast ephemeris data (received from tracked satellites). The algorithms predict orbital
parameters for up to three days. The module must operate in Full Power mode for at least 5
minutes to collect ephemeris data from visible satellites, or 12 hours for the full constellation.
EASY is disabled if the fix rate is > 1 Hz
EASY is on by default, but can be disabled by command $
PMTK869
.
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