GSA – GNSS DOP and Active Satellites
GNSS receiver operating mode, satellites used in the navigation solution reported by the GGA or GNS
sentence, and DOP values.
If only GPS, or GLONASS, or Galileo, or BDS, or QZSS, or NavIC (IRNSS) is used for the reported
position solution the talker ID is GP, GL, GB, GQ, GI respectively and the DOP values pertain to the
individual system.
If GPS, GLONASS, Galileo, BDS, QZSS, NavIC (IRNSS) are combined to obtain the reported position
solution multiple GSA sentences are produced, one with the GPS satellites, another with the GLONASS
satellites, another with Galileo satellites, and another with BDS, etc. Each of these GSA sentences shall
have talker ID GN, to indicate that the satellites are used in a combined solution and each shall have the
PDOP, HDOP and VDOP for the combined satellites used in the position. The GNSS System ID data field
identifies the specific satellite system.
When multiple GSA sentences are necessary, use of the NMEA TAG Block structure (§ 7) and the TAG
Block Sentence-grouping Parameter (§ 7.9.3) reliably links the related sentences together over any
transport medium.
When GSA sentences are provided with related GRS and/or GSV sentences, use of the NMEA TAG
Block structure (§ 7) and the TAG Block Sentence-grouping Parameter (§ 7.9.3) reliably links the related
(different sentence formatters) sentences together over any transport medium.
【NMEA 4.11】
$--GSA,a,x,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,x.x,x.x,x.x,h*hh
【NMEA 4.10】
$--GSA,a,x,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,x.x,x.x,x.x,h*hh
【NMEA 3.01】
$--GSA,a,x,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,x.x,x.x,x.x*hh<LF