ashtech DG14, Reference Manual

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60 DG14 and DG16 Board & Sensor Reference Manual
$PASHQ,RTC command.
Message Rate
To improve Differential performance, minimize base station data latency by
using the highest possible data rates that your data link supports. There are
three different settings that affect data rates:
• RTCM message bit rate.
$PASHS,RTC,SPD . This is the internal bit rate
used to generate the RTCM messages. This should be as high as possible
without exceeding the baud rate of the serial port. Recommended bit rate
setting is burst mode (9), which automatically adjusts the bit rate to the
fastest possible rate based on the serial port baud rate:
$PASHS,RTC,SPD,9
• Serial port baud rate. This should be as high as possible.
• RTCM message rate. This is the rate at which messages are generated.
• Differential messages (Type 1) are next most important, ideally once per
second. If the data rate does not support this, these messages may be
generated slower, with a corresponding decrease in differential accuracy.
Base Station Position
The RTCM message 3 broadcast the base station position.
Base Station Antenna Offset
If you set up the base station antenna over a known, surveyed point, you may
enter the position of the surveyed point and the offset from this point to the
antenna phase center. Or you may enter the phase center directly.
If you are using Type 3:
• At the base station, enter the phase center of the antenna directly using
$PASHS,POS or
• At the base station, enter the surveyed reference point using
$PASHS,POS and enter the antenna offset using $PASHS,ANT .
Using Reference Station ID
You may monitor which reference or base station the remote receiver uses by
setting a reference station ID at the base station. Set the reference station ID
using the command
$PASHS,RTC,STI .
You may also control which reference station the remote receiver uses by
setting the desired station ID at the remote receiver, or all the remote receiver
to use corrections from any base station.