Instruction manual

Understanding CPD Page 33
Understanding
To output the NMEA messages, use the $PASHS,OUT and $PASHS,NME
commands.
If for any reason the CPD solution cannot be computed for an epoch, there will be no
CPD solution output for that epoch in any real-time or NMEA message.
Other solution messages are also available for query, and not to output periodically
like PBEN or CBEN messages. These messages are UBN and OBN. The UBN
message gives CPD position, velocity, and statistical information in binary format.
The OBN message gives CPD vector and site information in binary format.
Vector Solution Output
This capability allows you to log vector solutions containing the same information as
post-processed vector output files (O-file), allowing the position solutions to be
imported into an adjustment program. Your Real-time Z solutions may then be
included as part of a least-squares network adjustment.
To use this option, a valid site name must be entered (check by using the
$PASHQ,RAW command), and the rover’s GPS antenna must remain stationary until
the site name has been changed to “????.” If the GPS antenna is moving with a site
name entered, the vector solution will not be valid. If no site name is entered, the
vector solution will not be created. Note that a site name must be entered at the base
station as well.
Other Ashtech Real-time Z products, such as GPSTopo, with software running on a
handheld datalogger automate this process, but it may be performed in the basic Real-
Time Sensor system using the following procedure:
1. Check the solution, as described in “Monitoring the CPD Rover Solution” on
page 31, to ensure that the current accuracy meets your requirements.
2. Place the antenna over the point to be measured.
3. Issue the following serial commands to the receiver using Ashtech’s
REMOTE.EXE program or a similar serial communication:
$PASHS,CPD,DYN,0
$PASHS,CPD,FST,OFF
$PASHS,SIT,xxxx (where xxxx is the site name you wish to use other
than ????)
These three commands set rover motion dynamics to static, turn Fast CPD
off, and set a site name.