Filter
Top Products
1 Quick Start
8 MiLLennium Command Descriptions Manual
to collect updated ephemeris data as well.
A delay of 120 to 130 seconds will typically ensure that the rover stations have collected updated ephemeris. After
the delay period is passed, the reference station will begin using new ephemeris data. To enter an ephemeris delay
value, you must first enter a numeric placeholder in the DGPS delay field (e.g., 2). When operating as a reference
station, DGPS delay will be ignored (see the
DGPSTIMEOUT command found in Chapter 2 and Appendix C for
further information on using this command at rover stations.)
Syntax:
Example:
dgpstimeout 2,300
USING RTCM SC-104 LOG TYPES
RTCM SC-104 is a standard for transmitting differential corrections between equipment from different
manufacturers. The NovAtel GPSCard is capable of transmitting or receiving
RTCM data.
To facilitate transmitting the
RTCM data over shared data links, the GPSCard is also capable of sending the RTCM
log in NovAtel ASCII format (RTCMA) or with the NovAtel Binary Header (RTCMB) added to allow
synchronous transmission and reception along with other data types.
REMEMBER: When sending or receiving RTCM log types, it is important to ensure that all connected
equipment are using the same RTCMRULE for compatibility.
The easiest method to send RTCM Standard logs is from the COM1 or COM2 ports of the reference GPSCard. The
easiest method to receive the RTCM data is through the COM1 or COM2 port of the rover GPSCard. The rover
GPSCard must issue the “ACCEPT port RTCM” command to dedicate a port before it will accept the
RTCM data
into that port.
The
RTCMA log can be intermixed with other NovAtel ASCII data over a common communication port. It will be
directly interpreted by a rover GPSCard as a Special Data Input Command ($RTCM). “ACCEPT port
COMMANDS” must be used with this input command. A non-NovAtel rover station will need to strip off the
header ($RTCM) and terminator (*xx), then convert the hexadecimal data to binary before the RTCM Standard
data can be retrieved.
The
RTCMB log can be intermixed with other NovAtel Binary data over a common communication port.
REMEMBER: Use the CDSA/B logs to monitor the COM port activity, success, and decoding errors.
USING RTCA LOG TYPES
The RTCA (Radio Technical Commission for Aviation Services) Standard is being designed to support
Differential Global Navigation Satellite System (DGNSS) Special Category 1 (SCAT-I) precision approaches. The
perceived advantage to using
RTCA type messages for transmitting and receiving differential corrections versus
using
RTCM type messages is that RTCM transmits 30-bit words, and the data is difficult to decode and process
because of the parity algorithm and regular word sizes used.
RTCA is transmitted in 8-bit words, which are easier
DGPSTIMEOUT dgps delay ephem delay
Command Option Description Default
DGPSTIMEOUT Command
dgps delay min. 2
max. 1000
Maximum age in seconds 60
ephem delay min. 0
max. 600
Minimum time delay in seconds 120