ashtech DG14, Reference Manual

Page: 63 / 390

Basic Operation 43
Basic Operation
When in Differential Base Mode, the DG16 uses an accurate antenna position
(reference position) entered by the user to calculate range corrections by
subtracting the measured range from the true range. Two commands can be used
to enter the reference position:
$PASHS,POS (position setting including latitude, longitude, altitude).
$PASHS,ALT (antenna height setting).
The DG16 can output a variety of NMEA messages and Ashtech-format NMEA-
style messages. Standard NMEA messages are output as a string of ASCII
characters delimited by commas, in compliance with NMEA 0183 Standards
(version 3.0). Ashtech-format NMEA-style messages are also output in a comma-
delimited string of ASCII characters, but may deviate slightly from NMEA
standards. For example, the maximum length of a standard NMEA message is
eighty characters, but the length of some Ashtech-format messages goes beyond
eighty characters.
Both NMEA messages and Ashtech-format NMEA-style messages begin with a
dollar sign ($) and end with a Carriage Return/Line Feed <CR><LF> delimiter.
Any combination of these messages can be output through either serial port at the
same time, and you can even choose to send the same message to output
through both ports. The output rate is determined by the
$PASHS,NME,PER
command, and can be set to any value between 0.05 and 999 seconds depending
upon the update rate option installed (20, 10, 5, 2 or 1 Hz). For more information
see the Chapter 8, NMEA Commands.
The default setting for the output interval is one second. See Chapter 4,
Command/Response Formats, for more information on NMEA messages and
Ashtech-format NMEA-style messages.
DEFAULT SETTINGS
Output interval setting for NMEA messages and Ashtech-format NMEA-
style messages is one second.