We recently received our EMLID REACH units. First, I am a Land Surveyor in the U.S. with a heavy background in GNSS and UAS. We are very impressed with the REACH!
Our first test was to check a known survey monument set by the NGS. It was a Second Order Class 1 Vertical, Class A monument with B stability rating. Published accuracies were 2.9mm Ellip and 2.7mm Horiz at the 95% confidence level.
First, we setup the REACH on a tripod over the monument with a plumb bob (I know it’s not the best setup, but we were excited to try it out). We measured the height with a retractable construction tape measure (Again, not the most accurate height measurement).
Next, collected two separate 20-minute static observations with the REACH.
We downloaded the RINEX files from the REACH along with RINEX files from two NGS CORS Stations. One CORS station was located approximately 5.1km (3.2 miles ) away and the other approximately 50km (31.1 miles) away.
We then downloaded the RAPID ephemeris file from IGS.
Each observation was then post-processed using RTKLIB to the 5.1km station. We received a fixed observation with only 5-7 minutes of observation data. The absolute position of the REACH agreed with the published position of the NGS monument within 2cm horizontal and 3cm vertical. This error could be due to our less-than-ideal setup and measuring (i.e. plumb bob and retractable tape). The relative error between the two separate REACH observations was 1cm horizontal and 2cm vertical. This is excellent!
We then post-processed the 50km baseline using RTKLIB. The absolute position of the REACH agreed with the published position of the NGS monument within 37cm (1.2 ft) horizontal and 73cm (2.4 ft) vertical. We didn’t think that was too bad considering L1 only and a 50km baseline!
Our plans are to test the same conditions as above using RTK and receiving corrections from a State-Wide CORS Network.
Also, we are in the process of testing the REACH compared to a PIKSI on a UAS with and without GCP’s to check the accuracy differences. We have a “test course” setup with 13 GPS’s all set to less than 1cm horizontal and vertical accuracy for verification.
Thanks to everyone who made REACH possible! We are excited to use it in our commercial operations and continue watching it evolve!