Today I had a wonderful opportunity to compare different GNSS receivers with Emlid Reach RS+. We the colleagues from http://lmb.lv we were measuring 3 points in the city environment with following antennas:
- Leica GS18
- Leica GPS900
- Altus NR3
- Altus NR2
- Trimble R4
- Emlid Reach RS+
Measuring setup was as following: RTK with LatPOS network, 10 sec measurement of each point in FIX, handheld pole (2 m).
The results were really good. Almost all of the receivers showed 2 cm accuracy (standard for cadaster measurement in Latvia). Here is the list of deviations from the measurements of the same points, which were found in the local geodetic network.
Point is in a small well, located very close to the building. With Emlid it was really hard to get FIX here, but after a small walk initialization was found and everything went well.
Results of the measurements (deviations in meters):
dx dy dz Leica GPS900 -0,033 -0,018 0,006 Emlid Reach RS+ 0,016 -0,002 0,006 Altus NR3 -0,014 0,006 -0,006 Leica GS18 0,001 -0,007 0,007 Trimble R4 could not acquire FIX Altus NR2 -0,001 -0,013 0,013
Point is a geodetic sign. Quite good observation of the sky. FIX status was acquired in 1.5-2 minutes. All other receivers acquired FIX in ~15-20 seconds. I think, it is because of L1+L2 receivers.
Leica GPS900 0,003 -0,004 -0,038 Emlid Reach RS+ 0,003 0 -0,038 Altus NR3 0,003 -0,001 -0,051 Leica GS18 -0,004 0,004 -0,031 Trimble R4 -0,003 0,001 -0,042 Altus NR2 -0,006 0,005 -0,029
FIX status was acquired in 20 seconds. I had to experiment with different configurations (Fix-and-hold and Continuous), as well as with different networks in LatPOS system (NETW-iMAX and Virtual RS).
Results: Leica GPS900 0,005 -0,001 -0,038 Emlid Reach RS+ 0,005 -0,009 -0,038 Altus NR3 0,013 -0,009 -0,044 Leica GS18 0,008 -0,008 -0,051 Trimble R4 -0,003 -0,002 0,015 Altus NR2 0,01 -0,006 -0,046
Overall, I am more than happy with the results. I have to admit, that local NTRIP base station was very near to the receivers, so that’s why everyone have good centimetre level accuracy. I will need to conduct the same experiment, but with the points, that are far from the local NTRIP stations.