Gps Survey Method

Static GPS surveying

The basic method of applying static GPS is to use two GPS receivers to measure a GPS baseline distance. The line between a pair (2 sets) of GPS receivers from which simultaneous GPS data have been collected and processed is a vector, referred to as Baseline. GPS receivers are set up over stations of at least one known point, and the second receiver can be placed in an unknown point. Both receivers must receive signals from the same four, or more satellites for a period of time (time depends on conditions of observation and distance required).

The important gists of Static GPS surveying are common satellites and common timing. Common satellites observations are required to formulate a correct vector (baseline) differences between these GPS receivers. Common timing refers to that receivers must receive signals under the same timing. Prior to the common satellite basis, it will defeat the purposes of static GPS surveying if receivers receive signals at different timing and collect different data that cannot be used.

The advantage of Static GPS survey is its high accuracy and less expensive. However, it consumes a lot of time due to station occupation time. In conclusion for Static GPS surveying, 2 or more GPS receivers can be used. Two critical factors are common timing and satellites observation.

Why common timing (simple illustration using 2 GPS receivers):

12pm – 12:30pm (A.C), 12:30pm – 1pm (Receiver C move to B) 1pm – 1:30pm (A.B) 12pm – 12:30pm (stop, moved to point B at 1pm)

C A

From this diagram, we can see that by using two receivers, the surveying continues its common timing principal even if one receiver is stopped. Because when the receiver moved to another point and starts its observation, the fixed point receiver is still continuing its observation simultaneously at the same time. This process will continue to progress with common timing rule.

Start survey at 1pm – 1:30pm

B

Illustrations Using 2...