Instruction manual

Operation Page 19
Operation
To change the output rate, issue the command $PASHS,NME,PER,x w here x is the output rate in
seconds.
Example: GGA message, Autonomous Position
$GPGGA,015454.00,3723.285136,N,12202.238517,W,1,08,01.0,+00012.
384,M ,,M,,00 00
Example: GGA message, RTCM differential
$GPGGA,015454.00,3723.285136,N,12202.238517,W,2,08,01.0,+00012.
384,M ,,M,002 ,0000
Example: GGA message, CPD differential (RTCM-RTK or DBEN)
$GPGGA,015454.00,3723.285136,N,12202.238517,W,3,08,01.0,+00012.
384,M,,M,00.123,0000
9. To stop GGA output, issue the command $PASHS,OUT,A.
10. To obtain additional setup information type $PASHQ,PAR and
$PASHQ,RAW.
Differential Setup
Differential operation is the major application of the Sensor. The Z-12 Real-time
Sensor provides the capability of real-time carrier phase differential (CPD), also
known as Real-Time Kinematic (RTK), in addition to the conventional RTCM
pseudo-range differential. This feature makes the Sensor ideal for navigation and
machine control, precision surveying, and extremely accurate positioning. The Sensor
produces the ultimate real-time precision: sub-centimeter accuracy under ideal
conditions. Coupled with the quick position update option, the Sensor can output
solutions at 1Hz, 2Hz, or 5Hz. All of these high-speed position updates are new,
independent solutions with extremely low latency, typically 100 to 125 milliseconds.
This section provides a step-by-step guide for the following three different
differential operations:
• Carrier phase differential (CPD)—Ashtech proprietary DBEN message
• Carrier phase differential (CPD)—RTCM-RTK type 18/19 message
• RTCM pseudo-range differential—RTCM type 1 message
Hard-wired data link
Differential operation requires a base station and a remote (rover) station. A radio is
normally used for the data link between base and remote stations. However, for this
instruction, the simplest and most reliable method for getting started is to use a hard-
wired RS-232 data link consisting of a null modem cable. This supplied serial data
cable serves this purpose.