|Zero Baseline RTK|
In another test to assess the performance of LabSat generated results, a LabSat was used to record the signals from a static survey grade antenna mounted on the roof. This signal was then passed into an RTK enabled survey GPS engine, an RTK Base Station and a LabSat at the same time using an RF splitter. Corrections from the Base Station were fed into the GPS engine, and an RTK lock was obtained almost instantly. The data from the GPS engine in RTK mode was logged, and the LabSat was used to record the GPS RF data to a laptop via USB.
The test was then repeated with the live antenna being substituted by the RF output from the LabSat and the recorded data was replayed.The following scatter plot shows the results from these two tests:
The Red points are from the Live antenna test, and the blue points are from the Replay test. The X&Y scales are in metres, so there is maximum deviation of about 8mm over the course of the test. You can see that the blue Replay test is just as accurate as the original Live antenna test in red. The positional accuracy was extremely good in both cases, proving that LabSat can accurately reproduce both the coarse acquisition code (C/A) and carrier phase information.
The GPS engine used in this test was a Javad TR-G3 running at 20Hz and utilising single frequency RTK.