JAVAD GNSS 5 Hz “Beast Mode” RTK Base Station Corrections Reduce the Time to Acquire a Fix by 72 Percent

by Matt Johnson

In another industry first, JAVAD GNSS has added the ability to transmit and process RTK base station corrections at rates greater once per second (1 Hz). The current industry standard has been to transmit and process corrections once per second. The JAVAD GNSS RTK engineering team recently hypothesized that increasing the rate of corrections would reduce the time for their RTK systems to acquire fixed RTK solutions. Mathematically the time required to acquire a fix is inversely proportional to the rate of the corrections.

Many existing RTK systems on the market have the ability to extrapolate 1 Hz corrections so that RTK positions can be computed at rates greater than 1 Hz. This innovation is advantageous with machine control applications where the GNSS antenna is in motion and it is desirable to know its position more than once per second. It, however, does not reduce the time required for the RTK engines to acquire fixed solutions. J-Field, JAVAD’s field software for the TRIUMPH-LS and Victor-LS, has RTK Verification and Validation features that reset the RTK engines to ensure a bad fix never gets accepted in areas under tree canopy and areas with high multipath. By reducing the time for the RTK engines to fix, RTK Verification and Validation can be completed much quicker and surveyors can collect points in locations that previously very difficult and time consuming.

J-Field and the RTK firmware have been improved to allow corrections to be processed at 2 and 5 Hz. These corrections can be transmitted through Javad’s UHF and spread spectrum radios or through the internet with a TCP connection between the base station and rover. Those who have used the TRIUMPH-LS with 5 Hz corrections have described the system as operating in “Beast Mode” due to its much improved performance. In a recent test to quantify the improved performance with acquiring a fixed solution, a TRIUMPH-LS was setup to automatically collect 100 points in succession with correction rates of 1 Hz, 2 Hz and 5 Hz. RTK Verification was used to reset the RTK engines once and then collect 1 epoch after at least 4 of the 6 parallel RTK engines of the system have fixed, essentially measuring the time required for 4 of the RTK engines to fix. The test location was in an environment with some multipath and an approximately 75 percent open view of the sky.

With 2 Hz corrections, the average time for 4 engines to fix was reduced by 46 percent to 6.7 seconds compared to 12.5 seconds with 1 Hz corrections.   With 5 Hz corrections it was reduced by 72 percent to 3.5 seconds. The JAVAD RTK engineering team currently has further plans to improve the RTK firmware to allow correction rates even greater than 5 Hz to be used and tested. With this and JAVAD’s continued commitment to develop new and innovative features, the limits and applications for survey grade GNSS receivers continues to expand.