Product specifications

Crescent Integrator’s Manual 38
You may query the Crescent Vector for the current heading rate time constant by
issuing the same command without an argument.
$JATT,HRTAU<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.
$JTAU,COG
The course over ground (COG) time constant allows you to adjust the level of
responsiveness of the COG measurement provided in the $GPVTG message. The
default value of this constant is 0.0 seconds of smoothing. Increasing the time
constant will increase the level of COG smoothing.
The following command is used to adjust the COG time constant.
$JTAU,COG,tau<CR><LF>
Where ‘tau’ is the new time constant that falls within the range of 0.0 to 200.0
seconds.
The setting of this value depends upon the expected dynamics of the Crescent. If
the Crescent will be in a highly dynamic environment, this value should be set to a
lower value since the filtering window would be shorter, resulting in a more
responsive measurement. However, if the receiver will be in a largely static
environment, this value can be increased to reduce measurement noise. The
following formula provides some guidance on how to set this value. If you are
unsure what is the best value for this setting, it’s best to be conservative and leave it
at the default setting.
tau (in seconds) = 10 / maximum rate of change of course (in °/s)
You may query the Crescent for the current course over ground time constant by
issuing the same command without an argument.
$JTAU,COG<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 0.0 seconds.
$JTAU,SPEED
The speed time constant allows you to adjust the level of responsiveness of the
speed measurement provided in the $GPVTG message. The default value of this
parameter is 0.0 seconds of smoothing. Increasing the time constant will increase
the level of speed measurement smoothing.
The following command is used to adjust the speed time constant.
$JTAU,SPEED,tau<CR><LF>