Low cost L1+L2 GNSS RTK receiver for Drones. North RTKite receiver.

Ralph Pendergraph February 22, 2016 at 4:11am

Hi,

I am a professional surveyor in the US and an owner/operator of a SmaRTK receiver. I am also a UAS owner going through the learning curve of UAV mapping. I am not an experienced UAS mapper at this point. I plan to work with the North Group to implement RTKite into my ultimate mapping solution. North Group has been great to work with on the survey side - very responsive and smart about everything GNSS.

Ralph Pendergraph, PLS

Anton Strydom February 22, 2016 at 2:18am

Good day to you

Sorry I forgot to add that by using a specific GEOID file accuracy in Z is very good especially after apply Helmert and doing a local transformation on my unit. If you have access to precision benchmarks the accuracy is even better

Anton Strydom February 22, 2016 at 2:16am

Good day to you

The U-Blox NEO 7N is not capable of doing RTK. I have developed a unit using a U-Blox LEA 6 T that does RTK.

Tests conducted using a motor vehicle comparing it to survey grade receivers (Leica SRX500, Geomax ZPG800, Leica 1200, Leica 900 and a Leica GMX 900) using local CORS system TRIGNET as well as setting up a dedicated base transmitting RTCM3 achieved the same results using the L1 unit as with the L1/L2 units doing RTK live.

Post processing the data from all the receivers also gave the same results with no difference between the L1 and the L1/L2 receivers.

Photo centers are also recorded as annotations in the RINEX files stored by the L1 receiver via a optically isolated relay that connects to the camera. The unit logs RINEX continuously and writes an annotation to the RINEX file each time the camera triggers.

Tests we conducted indicate that post processing the RINEX file is much more useful than RTK in the air especially in areas where CORS systems are not available. The unit that I developed has radio (range = around 50km) WIFI (range = around 4km) as well as cellular communication capabilities. The units are multi-functional as a unit can be setup as either base or rover.

If you use 2 units in a single drone you can also do dead reckoning if that is required by changing the setup of one of the units.

The units I developed are capable of accepting a L1/L2 receiver, the only reason for not using one is simply cost (cheapest receiver that I could find was Hemisphere for $900 where as the U-Blox cost me $ 45.)

The end result whether using L1 or L1/L2 was identical

Regards

Anton

Bernardo Espinosa February 21, 2016 at 6:12pm

Dear Darius Jack

The Ublox was the Neo7N that comes on the 3DR module (https://store.3dr.com/products/3dr-gps-ublox-with-compass)

The CORS used was the freely available network provided in Barcelona by CatNet (http://catnet-ip.icc.cat/)

However the SmaRTK / RTKite receivers are being used now in every continent and we have tested them with RTK Reference Stations of several countries including USA, Canada, Mexico, Honduras, Venezuela, Brazil, all over Europe, Egypt, Morocco, Bangladesh, India, Korea, Japan, Indonesia, Malaysia, just to name a few, so of course it is not limited to any country or communication protocol.

Were there are no CORS available, we have a unique P2P communication system by Cell Modem that can convert any SmaRTK or RTKite module on a CORS in 5 minutes, with same or better accuracy. That is the example test shown above with the DJI drone, using the SmaRTK as the ground base by GPRS. It is, as you mention, an "all-internet" solution already.

For the regions without cellular coverage, then the high power UHF radiomodems are available, up to 40W.

Our receivers are not directed for hobbyist, as I have mentioned, but for Professional or Semi-Professional users that need complete trust on the accuracy and real time without any waiting time, post processing or data offsets.

I hope this clarifies your questions.

Darius Jack February 21, 2016 at 3:21pm

@Bernardo,

what model of Ublox ?

M7, M8, M8 rtk ?

Since access to CORS station is provided by NOAA in US

and you reside in EU "On the European Space Agency, were we reside"

is your offer limited to US market only ?

Since access to ground based reference stations is limited, per request and contract,

so we should await for all-Internet RTK GPS technology solution

directed to hobbyists, at $100 (by Ublox or others) by the end of 2016.

Acorn February 21, 2016 at 6:59am

You can't describe something as "Low Cost" without stating the cost. It's a rule.

Bernardo Espinosa February 21, 2016 at 6:15am

This test was donde on a completly overcast sky, with some rain, and take off and landing was besides 10m high trees.

The terrain was rough, that stands for the Z difference on the RTK mode (that is accurate at about 8mm.

The RTK correction source was a government CORS station at about 20Km away with communication with the internal cellular modem.

In paralell we logged the normal UBLOX module used on the Pixhawk, that was the autopilot onboard.

Logging for Ublox was 5Hz and for the RTKite was 1Hz on this test, but it normally rates 10Hz.

Bernardo Espinosa February 21, 2016 at 6:07am

Hi all. I would like you to give you a bit of background. We are a -normally- surveying GNSS RTK producers, on the field since 10 years now. This year we started receivng a deluge of request for a tiny kind of receiver and we saw that indeed there was little on the market that would work as we like, that is, out of the box with zero integration.

Then we took our field proven SmaRTK platform with our unique SmartOS onboard operating system and shrinked all, with the exact same top-level components, into the RTKite.

On the European Space Agency, were we reside we are lucky to have handy some well-seasoned UAV developers to Beta testing was a breeze. (a few tests below, sorry text in spanish)

In short the RTKite is a FULL surveying-military grade GNSS RTK that is now available for broader use and now is being implemented on High accuracy machine control, Farming, Robotics and of course UAVS.

You can write us directly to emea@northgps.com for any question or suggestion. We can give you factory pricing as well of course, but as there are many options, its is better to do it that way to avoid mistakes, thank you for understanding.

P.S. We tried -and discarded- the L1 RTK way 6 years ago, the L1 has some inherent drawbacks that makes it unfit for professional use. We have L1 of course for is performs better on postprocessing and normal navigation.

Pascal P. February 21, 2016 at 12:10am

Yes, amazing how all the RTK systems are coming out fast these days. This one has an interesting L1/L2 features.

Price ?

Darius Jack February 20, 2016 at 4:46pm

http://northsurveying.com/index.php/instruments/gnss-rtk-receiver

@Bernardo,

so you are the winner and No.1 global manufacturer of L1/l2 RTKGPS

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Low cost L1+L2 GNSS RTK receiver for Drones. North RTKite receiver.

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