Chapter 3 | Operation |
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3.6.2Operational States
The receiver has 6 operating modes:
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•Initialization
•Acquisition
•Navigation
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•Fault
The receiver switches between modes automatically. The receiver reports the current operating and navigation modes on its host port.
1.Self-Test Mode
The receiver enters
2.Initialization Mode
Upon
The SMART ANTENNA retrieves data from both NVM and SRAM (warm start). Integrity checking is done on all data retrieved from the
During initialization, the receiver retrieves the last received valid almanac data and last user position from NVM, the current time from the
3.Acquisition Mode
The receiver is in Acquisition mode when insufficient satellite data is available to produce an initial navigation solution. Acquisition mode is entered from Initialization or
To acquire signals from the GPS satellites, the receiver uses:
•Almanac data which describes the satellite orbits
•Time, which in conjunction with almanac data is used to estimate the present position of satellites in their orbits
•The approximate location of the receiver so a prediction can be made as to which satellites are visible
The receiver then collects ephemeris data by decoding the satellite
If the receiver cannot perform an acquisition due to an absence of valid almanac data or user position and/or time, it initiates a "Search the Sky" acquisition. The receiver attempts to acquire all satellites in the GPS constellation. Once a satellite has been acquired, ephemeris data is decoded
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