The trimble software

During certain times of the day, you might have better satellite coverage than at other times because of the number of satellites that are in view and the position of a single satellite relative to the GPS receiver and other satellites in the constellation.
Trimble Navigation (www.trimble.com), one of the largest manufacturers of commercial and professional GPS receivers, has a free Windows program called Planning, shown in the figure here. Planning is designed for surveyors who need to know when the best time is to use GPS surveying instruments. Just enter the latitude and longitude coordinates of a location and the date, and Planning gives you information on

• DOP: Dilution of Precision describes how accurate a reported GPS position is. The smaller the DOP number, the higher the accuracy.
• Satellites: You can see how many satellites are in view if the sky is unobstructed, the optimumtimes of satellite visibility, and the satellite orbit paths. You don’t need to be a surveyor to use this information. Knowing optimal GPS times is useful for all sorts of outdoor activities. For example, if you’re serious about geocaching, you can select the best time of day to look for caches when your GPS receiver gives you the most accuracy. Planning is easy to use and works for any location in the world with all the GPS satellite information presented in graphs or lists.

To download Planning, go to www.trimble.com/planningsoftware_ts.asp?Nav= Collection-8425.