iSXblue/SXBlue II GNSS Series Technical Reference Manual
89
You may find a slight improvement in positioning performance using either the short or long smoothing
interval, depending on your multipath environment. The default for this command is 900 seconds (15
minutes) or LONG.
To change the smoothing interval to 300 seconds (5 minutes), or SHORT, use the following command:
$JSMOOTH,SHORT<CR><LF>
If you wish to change the smoothing interval to 900 seconds (15 minutes), or LONG, use the following
command:
$JSMOOTH,LONG<CR><LF>
You can also enter this command using the number of seconds you wish to use for smoothing. The limits
are from 15 seconds to 6000 seconds (100 minutes). Use the following command, where “X” is the
number of seconds you wish used for the carrier smoothing interval:
$JSMOOTH,x<CR><LF>
If you wish to request the status of this message, send the following command. It will return the word
SHORT or LONG as well as the number of seconds used. The status of this command is also output in the
$JSHOW message:
$JSHOW<CR><LF>
Note - If you are unsure of the best value for this setting, it is best to be conservative and leave it at
the default setting of LONG (900 seconds).
5.2.33
$JTAU
The $JTAU command allows you to adjust the level of responsiveness of the Speed and Course Over
Ground (COG). The command has the following structure
$JTAU,var,tc<CR><LF>
where ‘var’ is one of the two variables in the table below and ‘tc’ is the time constant
Var
SPEED
COG
•
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,tc<CR><LF>