GPS Receiver Board
GPS-24 / 24A Operating Manual
Rikaline
Specifications subject to change without prior notice
Rikaline
International Corp.
14F, 171, ChengGong Rd, Sanchong CityTaipei 241, Taiwan
Tel: ++886 2 8973 1899 Fax: ++886 2 8973 1896 E-Mail:
Web: www.rikaline.com.tw
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2. Operational characteristics
2.1 Initialization
As soon as the initial self-test is complete, the GPS-22 begins the process of satellite acquisition and
tracking automatically. Under normal circumstances, it takes approximately 120 seconds to achieve a
position fix, 42 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 GPS-22 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 If significant inaccuracy exists in the initial data, or the orbital data is
obsolete, it may take more time to achieve a navigation solution.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 FirstGPS™ architecture provides
superior performance. However, acquisition performance can be improved as the host system initializes the
GPS-22 in the following situation:
1. Moving further than 1,500 kilometers.
2. Failure of Data storage due to the inactive memory power back up.
2.2 Navigation
After the acquisition process is complete, the GPS-22 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 GPS-22 sets the default of auto-searching for real-time differential corrections in RTCM SC-104
standard format, with the message types 1, 2, or 9. It accomplishes the satellite data to generate a
differential (DGPS) solution. The host system, at its option, may also command the GPS-22 to output a
position whenever a differential solution is available.
