1)Latitude/longitude/altitude

2)Velocity

3)Date/time

4)Error estimates

5)Satellite and receiver status

Normally the GPS 35LP will select the optimal navigation mode (2D or 3D) based on available satellites and geometry considerations. The host system, at its option, may command the GPS 35LP to choose a specific mode of navigation, such as 2D. The following modes are available:

1)2D exclusively with altitude supplied by the host system (altitude hold mode)

2)3D exclusively with altitude computed by the GPS 35LP

3)Automatic mode in which the board set determines the desired mode based on satellite availability and geometry considerations

When navigating in the 2D mode (either exclusive or automatic), the GPS 35LP utilizes the last computed altitude or the last altitude supplied by the host system, whichever is newer. The host system must ensure that the altitude used for 2D navigation is accurate since the resulting position error may be as large as the altitude error. See Section 4 for more information on altitude control.

The GPS 35LP will default to automatic differential mode – “looking” for real-time differential corrections in RTCM SC-104 standard format, with message types 1,2,3, or 9, then attempt to apply them to the satellite data, in order to produce a differential (DGPS) solution. The host system, at its option, may also command the GPS 35LP to choose differential only mode. When navigating in the differential only mode, the GPS 35LP will output a position only when a differential solution is available.

2.4 SATELLITE DATA COLLECTION

The GPS 35LP will automatically update satellite orbital data as it operates. The intelligence of the GPS 35LP combined with its hardware capability allows these data to be collected and stored without intervention from the host system. A few key points should be considered regarding this process:

1)If the receiver is not operated for a period of six (6) months or more, the unit will “search the sky” in order to collect satellite orbital information. This process is fully automatic and, under normal circumstances, will take 3-4 minutes to achieve a navigation solution. However, the host system should allow the board set to remain on for at least 12.5 minutes after the first satellite is acquired (see Section 4 for more information on status indications).

2)If the memory backup battery fails, the receiver will search the sky as described above. Should the memory battery discharge, the unit needs to be powered on for several days to insure a sufficient recharge to maintain several months of clock operation and memory storage. System configuration information will not be lost due to battery discharge, only previous position, time and almanac data will be lost.

3)If the initial data is significantly inaccurate, the receiver perform an operation known as AutoLocate™ . This procedure is fully automatic and, under normal circumstances, will require 1.5

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