GPS for Dummies.pdf - Engineering Surveyor

80Part II: All About GPSIf you turn your GPS receiver off or if you lose satellite reception, the GPSreceiver stops recording tracks. When it’s turned back on again or good satellitecoverage resumes, the GPS receiver continues recording tracks, but it willassume that you traveled in a straight line between the last track locationsaved, before satellite reception was lost, and your current position.Some GPS receivers allow you to set how often tracks are saved, either bytime or distance intervals. For example, you could specify that a track besaved every minute or each time that you travel a tenth of a mile. Leaving thedefault, automatic setting for track collection should work for most occasions.However, if you’re using your GPS receiver for specialized purposes(such as mapping a trail), you may want to experiment with different intervalsto give you the level of detail that you need.When you reach your final destination, your GPS receiver can optionally usethe track log to help you navigate back to your starting point by using thetrack data to guide you retracing your steps. Check your user manual formodel specific instructions on how to do this.Tracks are probably one of the most useful GPS receiver features if you’reworking with digital maps. From a number of free and commercial mappingprograms, you can overlay your tracks on top of a map to see exactly whereyou’ve been. Figure 4-5 shows an example of track data collected during atrail run and then uploaded to a mapping program.Figure 4-5:Track datashowswhere youtraveled.