Holux GR-211, User Manual

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HOLUX
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2. Operational characteristics
2.1 Initialization
As soon as the initial self-test is complete, the GR-211 begins the process of satellite acquisition and
tracking automatically. Under normal circumstances, it takes approximately 45 seconds to achieve a position fix,
38 seconds if ephemeris data is known. After a position fix has been calculated, information about valid position,
velocity and time is transmitted over the output channel.
The GR-211 utilizes initial data, such as last stored position, date, time and satellite orbital data, to achieve
maximum acquisition performance. If significant inaccuracy exists in the initial data, or the orbital data is
obsolete, it may take more time to achieve a navigation solution. The GR-211 Auto-locate feature is capable of
automatically determining a navigation solution without intervention from the host system. However, acquisition
performance can be improved as the host system initializes the GR-211 in the following situation:
1) Moving further than 500 kilometers.
2) Failure of data storage due to the inactive internal memory battery.
2.2 Navigation
After the acquisition process is complete, the GR-211 sends valid navigation information over output
channels. These data include:
1) Latitude/longitude/altitude
2) Velocity
3) Date/time
4) Error
estimates
5) Satellite and receiver status
The GR-211 sets the default of auto-searching for real-time differential corrections in RTCM SC-104
standard format, with the message types 1, 5, or 9. It accomplishes the satellite data to generate a differential
(DGPS) solution. The host system, at its option, may also command the GR-211 to output a position whenever
a differential solution is available.