Product specifications

Crescent Integrator’s Manual 36
To show the current antenna separation, issue the following command.
$JATT,MSEP<CR><LF>
$JATT,HTAU
The heading time constant allows you to adjust the level of responsiveness of the
true heading measurement provided in the $HEHDT message. The default value of
this constant is 2.0 seconds of smoothing when the gyro is enabled. The gyro by
default is enabled, but can be turned off. By turning the gyro off, the equivalent
default value of the heading time constant would be 0.5 seconds of smoothing. This
is not done automatically, and therefore must be entered manually by the user.
Increasing the time constant will increase the level of heading smoothing.
The following command is used to adjust the heading time constant.
$JATT,HTAU,htau<CR><LF>
Where ‘htau’ is the new time constant that falls within the range of 0.0 to 3600.0
seconds.
Depending on the expected dynamics of the vessel, you may wish to adjust this
parameter. For instance, if the vessel is very large and is not able to turn quickly,
increasing this time is reasonable. The resulting heading would have reduced ‘noise’,
resulting in consistent values with time. However, artificially increasing this value
such that it does not agree with a more dynamic vessel could create a lag in the
heading measurement with higher rates of turn. A convenient formula for
determining what the level of smoothing follows for when the gyro is in use. If you
are unsure on how to set this value, it’s best to be conservative and leave it at the
default setting.
htau (in seconds) = 40 / maximum rate of turn (in °/s) – gyro ON
htau (in seconds) = 10 / maximum rate of turn (in °/s) – gyro OFF
You may query the Crescent Vector for the current heading time constant by issuing
the same command without an argument.
$JATT,HTAU<CR><LF>
Note: If you are unsure of the best value for this setting, it’s best to be
conservative and leave it at the default setting of 2.0 seconds when the gyro is
on and at 0.5 seconds when the gyro is off.
$JATT,PTAU
The pitch time constant allows you to adjust the level of responsiveness of the pitch
measurement provided in the $PSAT,HPR message. The default value of this