NorthStar 2505 Installation Manual page 16

SECTION ONE Introducing the 2505
2505 operating modes
Page 6
•
2-channel, fully automatic beacon differential GPS
reception for accuracy better than 2 meters 95 percent of
the time
•
user-selectable (via switch) WAAS-only or WAAS with
beacon back-up
•
WAAS accuracy better than 2 meters 2dRMS 95 percent of
the time
•
fully automatic operating modes; no user intervention
required
•
NMEA GGA and VTG messages at 5-Hz data rate
•
internal beacon/GPS antenna splitter
For a complete list of the 2505's technical specifications, see
"Appendix A Technical specifications" on page 19.
The 2505's GPS engine has seven operating modes:
•
Self-test
• Initialization
•
Acquisition
•
Navigation (includes four sub-modes: Differential 3-D,
Differential 2-D, 3-D Nav, and Altitude-Hold)
• WAAS/beacon differential
•
Dead-reckoning
•
Fault
The 2505 automatically switches between modes, and reports
the current operating and navigation modes through its host
port. The nine operating modes are described in detail below.
Self-test mode
The 2505 enters the self-test mode upon a host's request, using
an NMEA message, via the GPS primary port, using either
RS-232 or RS-422. This test requires no more than 15 seconds.
When the self-test is completed, the 2505 reports the test
results on its host port through another NMEA message, and
then proceeds either to initialization mode if the test was
passed or to fault mode if a problem was detected.
Initialization mode
The 2505 automatically enters initialization mode when power
is applied or after completion of self-test mode. While in
initialization mode, the 2505 retrieves satellite orbital data
(ephemeris or almanac) stored in its EEPROM memory.
Integrity checking is performed on all data retrieved from the
2505 INSTALLATION MANUAL, Revision A