Garmin GPS 25 LP Technical Specification

Garmin GPS 25 LP Technical Specification Manual pdf 11 page image

7Section 2Operational CharacteristicsThis section describes the basic operational characteristics of the GPS 25LP sensorboards. Additional information regarding input and output specifications are containedin Section 4.2.1 Self TestAfter input power has been applied to the GPS 25LP sensor boards and periodicallythereafter, the units will perform critical self test functions and report the results overthe output channel(s). The following tests will be performed:1) RAM check2) FLASH test3) Receiver test4) Real-time clock test5) Oscillator checkIn addition to the results of the above tests, the board set will report software versioninformation.2.2 InitializationAfter the initial self test is complete, the GPS 25LP will begin the process of satelliteacquisition and tracking. The acquisition process is fully automatic and, under normalcircumstances, will take approximately 45 seconds to achieve a position fix (15seconds if ephemeris data is known). After a position fix has been calculated, validposition, velocity and time information will be transmitted over the output channel(s).Like all GPS receivers, the GPS 25LP utilizes initial data such as last stored position,date and time as well as satellite orbital data to achieve maximum acquisitionperformance. If significant inaccuracy exists in the initial data, or if the orbital data isobsolete, it may take 1.5 minutes to achieve a navigation solution. The GPS 25LPAutoLocateTM feature is capable of automatically determining a navigation solutionwithout intervention from the host system. However, acquisition performance can beimproved if the host system initializes the board set following the occurrence of one ormore of the following events: