242 DG14 and DG16 Board & Sensor Reference Manual
$GPGSA
The GSA message contains indicators for current position mode (see the
$PASHS,PMD command on page 138), a list of the satellites being used to compute
position, and the values for PDOP, HDOP, and VDOP. This message is not output
until positions are being computed. The response is output in the format:
$GPGSA,c1,d2,d3,d4,d5,d6,d7,d8,d9,d10,d11,d12,d13,d14,d15,d16,d
17*hh
Table 8.14 outlines the message format.
Typical GSA message:
$GPGSA,A,3,31,29,23,26,,21,17,09,08,,03,,01.7,01.0,01.4*0B
Table 8.15 outlines the response message.
Table 8.14. $GPGSA Message Format
Parameter Significance
c1 Position mode indicator:
• A—Automatic mode
• M—Manual mode
A, M
d1 Position mode indicator:
• 1— Position fix not available
•2—2D mode
•3—3D mode
1, 2, 3
d3-d16 These 14 fields represent the receiver’s 14 channels listed in
ascending order. The number 17 appearing in field d5
indicates that DG16 channel 3 is locked on satellite 17. If a
given channel is not locked on a satellite, the corresponding
field will be empty.
SBAS satellites are indicated with numbers from 33 to 64.
1 to 64
d15 Current PDOP value 0 to 99.9
d16 Current HDOP value 0 to 99.9
d17 Current VDOP value 0 to 99.9
hh Checksum 2-character hex
Table 8.15. Typical $GPGSA Message
Field Description
$GPGSA Header
A Indicates automatic 2-D/3-D switching mode
3 Indicates 3D position mode
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