GPS for Dummies.pdf - Engineering Surveyor

Chapter 5: Selecting and Getting Started with a GPS Receiver97During certain times of the day, you might havebetter satellite coverage than at other timesbecause of the number of satellites that are inview and the position of a single satellite relativeto the GPS receiver and other satellites inthe constellation.Trimble Navigation (www.trimble.com), oneof the largest manufacturers of commercial andprofessional GPS receivers, has a free Windowsprogram called Planning, shown in the figurehere. Planning is designed for surveyors whoneed to know when the best time is to use GPSsurveying instruments. Just enter the latitudeand longitude coordinates of a location and thedate, and Planning gives you information onTrimble planning software DOP: Dilution of Precision describes howaccurate a reported GPS position is. Thesmaller the DOP number, the higher theaccuracy. Satellites: You can see how many satellitesare in view if the sky is unobstructed, the optimumtimes of satellite visibility, and the satelliteorbit paths.You don’t need to be a surveyor to use this information.Knowing optimal GPS times is useful forall sorts of outdoor activities. For example, ifyou’re serious about geocaching, you can selectthe best time of day to look for caches whenyour GPS receiver gives you the most accuracy.Planning is easy to use and works for any locationin the world with all the GPS satellite informationpresented in graphs or lists.To download Planning, go to www.trimble.com/planningsoftware_ts.asp?Nav=Collection-8425.