Hardware manual

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990-0000058-1000 Rev F Page 26
Table 4-2 NMEA Approved Sentence Structure
ASCII HEX DESCRIPTION
“$” 24 Start of Sentence
aa Dummy characters to start the Address Field (e.g. GP), not
used by EdgeTech products.
bbb Sentence Formatter. Mnemonic code identifying the data
type and the string format of the successive fields.
“,” 2C Field Delimiter. Starts each field except Address and
Checksum fields. If it is followed by a null field, it is all
that remains to indicate no data in the field.
c---c Data Sentence Block. Data field(s) preceded and separated
by delimiters.
“*” 2A Optional Checksum Delimiter.
hh Optional Checksum Field
<CR><LF> 0D 0A Terminates Sentence
4.3.1. Inputs
The following are the approved NMEA sentences recommended for use with the
DISCOVER based systems.
GLL – Geographic Position – Latitude/Longitude
Latitude and Longitude of the present vessel position, time of position fix and status.$--
GLL,xxxx.xxx,a,yyyyyy.yyy,b,hhmmss.ss,A*hh<CR><LF>
Table 4-3 GLL- Geographic Position-Latitude/Longitude
ARGUMENT
DESCRIPTION
xxxx.xxx Degrees|Minutes.decimal - 2 fixed digits of degrees, 2 fixed digits of
minutes and a variable number of digits for decimal fractions of minutes.
Leading zeros always included for degrees and minutes to maintain fixed
length.
a N for North Latitude or S for South Latitude
yyyyy.yyy Degrees|Minutes.decimal - 3 fixed digits of degrees, 2 fixed digits of
minutes and a variable number of digits for decimal fractions of minutes.
Leading zeros always included for degrees and minutes to maintain fixed
length.
b E for East Longitude or W for West Longitude