Specifications

BATS AND PORTABLE BATS OPERATION
3-47
For further information on the NMEA standard contact; NMEA, 7 Riggs Ave., Severna Park, MD 21146 U.S.A.,
Tel: [phone], http://www.nmea.org, E-Mail: [e-mail]
For further information on the TCM-2 format contact; PNI Corporation 133 Aviation Blvd, Suite 101 Santa Ro-
sa, CA 95403 USA, Tel: [phone], Fax: [phone], http://www.pnicorp.com/, E-Mail:
[e-mail]
The following describes the format of each of the NMEA and the TCM-2 compass sentences. If the
“Use Checksum” is checked, and the checksums do not agree, the data is ignored. If the “Use
Checksum” is not checked then the data is accepted even if the checksum does not agree or is
missing from the string. (The checksum is the 8-bit exclusive OR (no start or stop bits) of all char-
acters in the sentence, including “,” delimiters, between both, but not including, the “$” and the “*”
delimiters.) On the RS-232 target output data sentence there is no compass heading identifier to
distinguish between True and Magnetic heading information except on the NMEA ORE format.
The Heading data is continuously received from the Transceiver’s ComPort but only updates when a
valid target has been detected. The Model 4460B can accept heading information at data rates up
to 100Hz and baud rates up to 115.2k.
The various formats the system can receive are shown below;
HDT - Heading, True
1 2 3
| | |
$ --H D T , x . x , T * C S < C R > < L F >
Field Number:
1) Heading, degrees True
2) T = True
3) * = EOS Delimiter & CS = CheckSum
The Trackman software displays the heading data on the screen and adds a suffix ”T” to indicate
heading is True.
HDM - Heading, Magnetic
1 2 3
| | |
$ --H D M , x . x , M * C S < C R > < L F >
Field Number:
1) Heading, degrees Magnetic
2) M = Magnetic
3) * = EOS Delimiter & CS = CheckSum
The Trackman software displays the heading data on the screen and adds a suffix ”M” to indicate
heading is Magnetic.