37
Radian Motion Sensor
User Manual
Document Ref: UM-8041-C1
Issue: C - Rev 1
© Sonardyne International Limited 2007
The heading field will be null if it cannot be calculated.
Heading measurements are in degrees and decimals.
$HCHDM format
Fig 32 NMEA 0183 $HCHDM data format
Description
The header information includes the mnemonic
HDM
for Heading, Magnetic.
This telegram format requires deviation to be specified before it can include mag-
netic heading.
This format has been superseded by the HDG telegram format, described above,
but is still widely used.
$PHTRO format
Fig 33 NMEA 0183 $PHTRO data format
Description
This proprietary format from Octans includes pitch and roll information. It is sim-
ilar to the NMEA 0183 standard. The units for the measurements are degrees, the
angles are as described below.
Notes
The data string has variable length, with leading zeros if magnitude is less
than 1, and minus signs added where necessary.
Positive pitch is bow down, stern up.
Positive roll is port side up, starboard down.
Attitude measurements contained in the data string are in real time, valid for
the instant when Radian begins to transmit the string.
There is no status indicator in the string.
Start
character
$HCHDM,xxx.xx,M*hh<cr><lf>
Header
Comma
separator
Comma
separator
Checksum
Carriage-return,
line-feed
characters
Heading
type,
agnetic
M
Heading,
degrees
and
decimals
Start
character
$PHTRO,x.xx,a,y.yy,b*hh<cr><lf>
Pitch
sense:
M=
bow
up,
P=
bow
down
Roll,
degrees
and
decimal
Carriage-return,
line-feed
characters
Header
Comma
separator
Pitch,
degrees
and
decimal
Comma
separator
Comma
separator
Roll
sense:
B=
port
down,
T
=
port
up
Comma
separator
Checksum