Garmin APOLLO GX SERIES Service Manual

Contents

Garmin AT Rev --7-14 GX Service Manual © 2004 Garmin AT11. GPS PerformanceSetup: Connect the unit under test and the UPS Aviation Technologies-certifiedreference unit to an antenna or signal source as defined in the GPS SignalSource section on page 7-6.NoteThis test requires that the seed position, time, and date have been correctly set.Refer to the System Initialization and Seed Position, Time and Date paragraphson page 7-8 and 7-9.Operation: Turn on power to the GX unit and monitor the GPS status/position pages todetermine time to first fix. Check the lat/lon position accuracy by comparison tothe UPS Aviation Technologies-certified reference unit. Compare the signallevels of matching satellites to the reference unit. After the unit has acquired thesatellites, the GPS Sensor pages will be updated.Verification: Verify that the acquisition time is less than 2 minutes.Verify that the position is within 0.05 NM of the reference unit.Verify that the signal levels of the unit under test for the same PRN as thereference unit are similar (normalized reference unit signal level, ± 13) comparedto the normalized signal levels of the reference unit.Verify elevation and azimuth on the unit under test agrees with the reference toensure that the almanac is updated.Verify that the signal level for each tracked satellite is equal to or greater than thenormalized signal levels of the reference unit.Verify navigation by entering a direct-to waypoint on both the test and referenceunits and seeing that the bearing and range to the selected waypoint matchesthe reference unit.Notes: This test requires that the seed position is set to within 60 NM of the source, andtime and date have been set to within 5 minutes of the source. The specificationallows for a ± 5% tolerance margin between the normalized reference unit andthe unit under test. The acquisition time may take longer than two minutes if theGPS receiver does not have current almanac data. If this is the case, after theunit has acquired current almanac data, it may take up to 25 minutes to acquire acomplete almanac once the receiver has started tracking a satellite. Theacquisition time should be re-verified to meet the two-minute specification.12. Equipment MarkingDescription: The configuration and marking for the GX unit is defined on the unit configurationdrawing and the unit assembly drawing. The versions of all assemblies must bevalid as described on the drawings.Setup: N/AOperation: Using the current unit configuration drawing, check the hardware configurationand the equipment marking (UC tag).Verification: Verify the hardware/software configuration is valid and the UC tag marking iscorrect. Verify that labels are installed as defined on the unit assembly drawing.