18
Sentenc
e
Output by Default?
Maximum Characters
GPRMC
74
GPGGA
82
GPGSA
66
GPGSV
70
PGRME
35
GPGLL
44
GPVTG
42
PGRMV
32
PGRMF
82
PGRMB
40
PGRMM
32
PGRMT
Once per minute
50
Table 2: NMEA 0183 Output Sentence Order and Size
Baud
Characters per Second
4800
480
9600
960
19200
1920
38400
3840
Table 3: Characters per Second for Available Baud Rates
The maximum number of fields allowed in a single sentence is 82 characters including delimiters.
Values in the table include the sentence start delimiter character “$” and the termination delimiter
<CR><LF>. The factory set defaults result in a once per second transmission at the NMEA 0183
specification transmission rate of 4800 baud.
4.2.2 Transmitted Time
The GPS sensor outputs Coordinated Universal Time (UTC) date and time of day in the
transmitted sentences. Before the initial position fix, the on-board clock provides the date and
time of day. After the initial position fix, the date and time of day are calculated using GPS
satellite information and are synchronized with the closest UTC second boundary.
The GPS sensor uses information obtained from the GPS satellites to add or delete UTC leap
seconds and correct the transmitted date and time of day. The transmitted date and time of day
for leap second correction follow the guidelines in
“National Institute of Standards and
Technology Special Publication 432 (Revised 1990)”
(for sale by the Superintendent of
Documents, U.S. Government Printing Office, Washington, D.C., 20402, U.S.A.).
When a positive leap second is required, one second is inserted at the beginning of the first hour
(0h 0m 0s) of the day that the positive leap is occurring. The minute containing the leap second is
61 seconds long. The GPS sensor would have transmitted this information for the leap second
added December 31, 1998 as follows:
$GPRMC,235959,A,3851.3651,N,09447.9382,W,000.0,000.0,311298,003.3,E*65
$GPRMC,000000,A,3851.3651,N,09447.9382,W,000.0,000.0,010199,003.3,E*64
$GPRMC,000000,A,3851.3651,N,09447.9382,W,000.0,000.0, 010199,003.3,E*64
$GPRMC,000001,A,3851.3651,N,09447.9382,W,000.0,000.0, 010199,003.3,E*65
If a negative leap second should be required, one second will be deleted at the end of some UTC
month. The minute containing the leap second will be only 59 seconds long. In this case, the GPS
sensor will not transmit the time of day 0h 0m 0s (the “zero” second) for the day from which the