Tritech MicronNav - NMEA $RATTM

Using the External Computer Data Link MicronNav System
0656-SOM-00001-07 117 © Tritech International Ltd.
7.2.6. NMEA $RATTM
This NMEA ‘Tracked Target Message’ is a commonly used string in charting/navigation
packages. The comma-separated ASCII string contains the target Range & Bearing and UTC
Time-stamp. Target speed and course are not calculated and so are not contained in the
string. Any fields with no calculated data will be padded with zero value data.
The full string format is as follows:
‘$RATTM’ Reply Data Structure
Data Description Data Range Field Range
NMEA string header Always ‘$RATTM’ hhhhhh
Comma separator Always ‘,’ ,
Target number 00 to 99 ii
Comma separator Always ‘,’ ,
Horizontal Target Distance from vessel (in
nautical miles)
0 to 9.9999 d.dddd
Comma separator Always ‘,’ ,
Target Bearing (degrees) 0 to 359.9 bbb.b
Comma separator Always ‘,’ ,
Bearing Degrees identifier ‘R’ or ‘T’ ‘R’ (Relative) or ‘T’ (True)
Comma separator Always ‘,’ ,
Target Speed, not calculated so padded
with zero
Always ‘0.0’ s.s
Comma separator Always ‘,’ ,
Target Course, not calculated so padded
with zero
Always ‘0.0’ c.c
Comma separator Always ‘,’ ,
Degrees identifier, unused so defaulted to
‘T’
‘R’ or ‘T’ ‘R’ (Relative) or ‘T’ (True)
Comma separator Always ‘,’ ,
Distance of closest point of approach, not
calculated so padded with zero
Always ‘0.0’ p.p
Comma separator Always ‘,’ ,
Time to CPA, min, ("-" increasing), not
calculated so padded with zero
Always ‘0.0’ t.t
Comma separator Always ‘,’ ,
Speed/Distance units Always ‘N’ (nautical miles) K/N/S (km/ nautical miles/
statue miles)
Comma separator Always ‘,’ ,
Target name (0 = Responder, 1..15 =
Transponder)
e.g. “TARGET0” to
“TARGET1”
ASCII variable field
Comma separator Always ‘,’ ,
Target Status ‘L’ or ‘T’ L = Lost, Q = Query in
process, T = Tracking
Comma separator Always ‘,’ ,
Target ? Always null R = Reference Target,
otherwise null