User's Manual

ZYM-GM7033-MF Production Data
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Glead Electronics www.glead.com.cn P0.1 2021. 06. 07
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Appendix A Software Protocol
A.1 NMEA Transmitted Message
NMEA is the standard of GNSS protocol. Cynosure GNSS receiver
supports several NMEA sentences: GGA, GSV, GSA, RMC, VTG,
ZDA, GLL and GRS. This data set includes the complete PVT
(position, velocity, time) solution computed by the GNSS receiver.
Each sentence has a prefix beginning with a '$' and ends with a
carriage return/line feed sequence and can be no longer than 80
characters of visible text (plus the line terminators). There is a
provision for a checksum at the end of each sentence which may or
may not be checked by the unit that reads the data. The checksum
field consists of a '*' and two hex digits representing an 8 bit
exclusive OR of all characters between, but not including, the '$' and
'*'. A checksum is required on some sentences.
Different prefix indicates the global position satellite systems for
sentences GRS, GSA and GSV:
$GP for GPS-only
$BD for BEIDOU2-only
$GL for GLONASS-only
$GN is for GNSS, combination of different global position satellite
system.