Garmin GPS 35 LP Technical Specification

Also see for GPS 35 LP: Declaration of conformity Quick start guide Technical specification

Contents

Garmin GPS 35 LP Technical Specification Manual pdf 10 page image

61) Latitude/longitude/altitude2) Velocity3) Date/time4) Error estimates5) Satellite and receiver statusNormally the GPS 35LP will select the optimal navigation mode (2D or 3D) based on available satellitesand geometry considerations. The host system, at its option, may command the GPS 35LP to choose aspecific 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 35LP3) Automatic mode in which the board set determines the desired mode based on satellite availabilityand geometry considerationsWhen navigating in the 2D mode (either exclusive or automatic), the GPS 35LP utilizes the lastcomputed altitude or the last altitude supplied by the host system, whichever is newer. The host systemmust ensure that the altitude used for 2D navigation is accurate since the resulting position error may beas 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 correctionsin RTCM SC-104 standard format, with message types 1,2,3, or 9, then attempt to apply them to thesatellite data, in order to produce a differential (DGPS) solution. The host system, at its option, may alsocommand the GPS 35LP to choose differential only mode. When navigating in the differential onlymode, the GPS 35LP will output a position only when a differential solution is available.2.4 SATELLITE DATA COLLECTIONThe GPS 35LP will automatically update satellite orbital data as it operates. The intelligence of the GPS35LP combined with its hardware capability allows these data to be collected and stored withoutintervention 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 normalcircumstances, will take 3-4 minutes to achieve a navigation solution. However, the host systemshould 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. Shouldthe memory battery discharge, the unit needs to be powered on for several days to insure asufficient recharge to maintain several months of clock operation and memory storage. Systemconfiguration information will not be lost due to battery discharge, only previous position, time andalmanac data will be lost.3) If the initial data is significantly inaccurate, the receiver perform an operation known asAutoLocate™. This procedure is fully automatic and, under normal circumstances, will require 1.5