RTK GPS Explained. What are the benefits? (with HolyBro F9P hardware)

hello and welcome to the video I'm here at 3dxr sat with Ben of 3dxr and this whole video is about rtk GPS now rtk GPS is something that I get asked about a lot it's not something that I use as a hobby grade flyer but it's something that Ben deals with on a regular basis now holy bro have just brought out some new technology a new Rover and a new base station GPS system so I thought this is a perfect opportunity then while I'm here and I have Ben's brain to make a video to kind of talk about what rtk is how you use it and to get Ben to give a little demo of how you set it up so let's start at the very beginning I'll put time codes down below and links to these bits and pieces on the 3dxr website let's talk about first of all what is rtk GPS Ben okay so rtk is the real-time kinematic correction so in this setup here what we need is a base and a Rover and the bass transmits corrections to the Rover and we in this case you can get sort of centimeter accuracy relative to the base um it's a very neat solution from hollybro here so the big did the big headlines with this is the reason that you'd use rtk GPS is although you need two GPS's one connected to a base station and then another one on the model is that you get sub two centimeter accuracy versus a couple of meters now if you're a hobby grade flyer having a return to home Landing in more or less the same spot it's absolutely fine but there's lots of reasons why you might want that very accurate location isn't it yeah so there's um sort of a couple of main uses we see for rtk and for it can be used for navigation um or some people will use it for mapping so what I must remember is that the accuracy is relative to what bass you use so if it's your own base or if it is a n-trip service um and some benefits used for navigation would be a highly accurate repeatable sort of flight paths and improve your return to home accuracy so land ending on the same spot and and repeating a sort of pattern so rtk it would be a good use on a lawnmower where you want to precisely fly a grid to corollary grass and you want to be able to repeat that a setup like this could be easily set up on your vehicle and also at your premises so you'd set up your fixed base and what we saw from our demonstration earlier is within seconds we had a rtk fix and we're receiving those Corrections and our accuracy became sort of centimeteracular relative to our base so you would really use this if you're more of a professional flyer if you're using surveying mapping photogrammetry or you have a Rover and you want it to maybe follow a very very specific path to kind of sub centimeter accuracy then this is exactly what you need to do now you mentioned a couple of things and this system needs two GPS's not one doesn't it to work properly so what are the two parts that you need to get yeah what we've got here is the f9p family if you like so the big disk here is we call this a Rover this is what on the moving vehicle but although you call it a Rover it's not just for cars yeah the term Rover in this case is you know it's moving about right yeah so yeah nothing to do with the vehicle this is called uh the Rover something you know sometimes it could be a network Rover depending on how you connect but yeah this one's the the Rover if you like so on the vehicle moving around and then for this simple setup we have the base um for Simplicity today we just had the helical antenna quite often if we were set up on a tripod or stuck to a wall we might have a bigger um antenna um if it's a permanent installation you would use some sort of waterproof antenna stuck to the side of a building on a vehicle and but yeah we've got these um two sit-ups here so when we're when we're talking about GPS we'll call it a Rover and a base the base um is transmitting corrections to the Rover and these GPS's must also be capable of rtk so when you see sort of rtk ready what that means is it's got a GPS chip inside so in this case it's a u-blocks f9p that is capable of receiving Corrections for the one on the Rover and it's capable of acting as a base on the base station so the other thing we need for this then I'm guessing is some kind of telemetry connection to the Rover GPS so that you can send those Corrections all the time so something like these holy bro Telemetry radios that we're using here is a perfect thing for that simplest option here the 433 radios from hollybro and they are transmitting the correction from the base to the Rover obviously there's many other radios you can go over the RF designs you can send over the links like healing so a way to get that correction from the base to the Rover so what rtk is then is it is a much more accurate fix but all the fix is relative to the base station so the base station lock can be up to a couple of meters but then the relative position of the flying part or the Rover or the quad or wherever it is to the base station is kind of sub centimeter accurate once you've got it all set up properly so what we'll do is let's just quickly walk outside and Ben can go through the process to quickly put this all together so here we've got our demo setup in order to show the rtk correction going to our f9p Rover so on our demo board we've got a flight controller with the f9p Rover plugged in and it has a Telemetry radio which is connected to this laptop where we're going to set up the base so in order to start transmitting Corrections we need a base correct connected to this laptop so here we have the hollybro f9p helical and we're going to connect it via USB to the laptop the rtk settings are found in setup optional Hardware rtk GPS we'll select the com port EE base in this case com34 it's a f9p so I'll tick the u-blocks auto config and also this additional box it's going to survey in for to for one minute to an accuracy of two meters now this is the relative accuracy of the base so let's connect and what we have here is the green bars have appeared showing the different satellites we're connected to and the bar is an indication of sort of signal to noise ratio so we're going to start um surveying in in order to get a valid base position so here we've got GPS glonass Bido Galileo and we'll start collecting a base position on the right this is the duration of the survey in so seven seconds this current accuracy is in meters and that's the the sort of relative accuracy of the base once it's achieved this sub 2 meter um accuracy and over 60 seconds has passed we can save and use this position so it's just about to hit the sub 2 meter which it has now and in order for the position to be valid we must have also satisfied the time requirement of 60 seconds which is coming up and then we now have a valid base position so we can save the current base position we'll just call it test and now we can use this position to start transmitting Corrections so I've clicked on use and if we go back to the main screen and connect to our vehicle confetti too when it's established a connection it's now going to be able to start transmitting the corrections and what we should see the normal 3D fix change to a float and then an rtk fix depending on the hardware you're using this could take seconds or minutes so let's have a we've got an rtk float which is good and now instantly rtk fix so we are now using um rtk to fixed position we've got an accuracy to a centimeter accuracy to our base and our base is sort of relatively accurate to a couple of meters so this is now using rtk the message you saw before that where it said rtk Float that's where it's receiving corrections but it hasn't calculated the solution these f9ps are very good GPS and it's a very quick to attain an rtk fix that was seconds in this case so Ben thanks for doing the demo I Now understand how to use this stuff there are a couple of things to think about because it does mean that if you have this system you don't just immediately get subcenter meter accuracy first of all is to remind everybody that this that centimeter accuracy is between the base station and the vehicle once it's all set up and calibrated because the corrections are being sent so it's really important that the base station you know the position absolutely accurately so if you're stood on on OS survey points that's going to help but there are professional systems and other things you can do in order so that you know exactly where the base station is it does mean though if you have the base station in the same position every time when you fly you can do those repeatable flights to within a very very tight margin so whereas with a normal model you could be within a couple of meters if you're flying the same Mission over and over again if you're mapping that might not be be what you need so by using this and having the base station in the same location you can get that reproducibility however a couple of other things you were talking about the fact that if you stick this system on something that's going at a pretty quick Pace you also could lose some uh yeah so I guess that touches on the the mapping side so quite a lot of time people want to improve the accuracy of geotaged imagery taken on a drone and for mapping and so you can do that by rtk so that that will absolutely improve um the the Geo information that you collect in flight and there's another method called PPK which is to post process the data and the reason why you might wish to do it that way is to try and get the best position of where that photograph was taken so if you imagine a fixed Wing mapping drone traveling at 20 meters a second and we're to look at sources of error this rtk system here operates five Hertz when it's receiving a correction and what happens is during the time between readings the planes actually move four meters in this case right so when when was the picture taken um how do you get centimeter accuracy if every reading is essentially four meters apart by logging the GPS data and post-processing that that's one step to improve the data seal interpolate the position other methods so we'll just slightly touch on this on this video for people that want to improve the mapping accuracy and we were mentioned in previous videos about the hot shoe feedback so exactly when the picture was taken and then things to consider such as the position between the camera and the antenna so often there's an offset there of more than the desired accuracy so a really big model and the camera is hanging off the nose and the GPS is out the back out the way then potentially it could be a meter so the position can be out by that of course um another thing that can happen say let's say for example serving a large area with a swing the antenna on the vehicle as you bank over you'll lose satellites and you could potentially lose the rtk fix so it could drop down to a float or a standard fix so my preference when doing large area fixed Wing mapping would be the PPK approach so post processing the data to get the best results on multi-road flights lower speed gentler turns yeah rtk is a very nice way to do it nice and simple and there is another use of rtk and it's a sort of I guess growing issue for some people on certain Vehicles where you know the compass doesn't perform very well so we can actually put two of these for example the helical one on an aircraft and because we've got such a um accurate position of where these GPSs are we can use that for heading so if you know where two points are okay so let's say they need to be a minimum 30 40 centimeters apart the bigger the better and that's efficient enough to give a heading so we can use GPS for your and eliminate compasses on aircraft where that has been challenging you know due to interference the Run of cables the size of the motors so a very good use of these um holyboro f9ps is to be used for as um heading and that can be with a base on the ground or there's also a technique where you have a moving base so one of the GPS's on the aircraft is actually the base but it's moving and then the Rover's been corrected so it's yeah it's it's been out for a little while but um that's an option for people that are struggling with large aircraft and Compass issues so hopefully that's helped those of you that were trying to figure out what rtk GPS is so it is a way to go from a couple of meter accuracy which is what we'll get out of the regular GPS's we're using the hobby down to kind of sub to one centimeter accuracy but again remember that the accuracy that we're talking about here with rtk is relative to the base station so if the base station is moved or in a different location that accuracy is going to change as well so you kind of have to survey in almost your base station if you want to know on an OS grid exactly where that piece of information that photograph was taken and it isn't the complete answer for fast-moving vehicles and for real Precision there is something called PPK that you may have to do which is post processing which is where you can take all the information from the flight all the correction data all the information from the log files and actually create a very very accurate view of how everything worked so hopefully that's helped if you have any questions do pop them down below and if we get enough of them we may even do another video going into this in a little bit more depth thanks to Ben for the time today and I'll put again links down below to all this stuff on his website thank you for watching the video if you watch my videos and find them useful then please take a moment to hit the like And subscribe button it helps the channel a lot if you really like what I'm doing here you can become a patreon and support the time I spend helping others and get access to lots of exclusive benefits link is in the video description remember that all the videos on the channel are organized into playlists so you can easily use those playlists to find all the videos on a subject that you are interested in add painless 360 to your searches on Google and YouTube and it'll help you find my content for any particular topic thanks again for watching and as always happy flying [Music]

Channel: Painless360

Views: 21,321

Keywords: Radio control, remote control, setup, easy, need, help, simple, tricks, tips, model, flying, drone, electronics, pilot, builder, maker, print, fpv, first person view, plane, wing, air, hover, fly, camera, transmitter, frequency, problem, need help, how to, gadget, technology, computer, app

Id: C0noxfMWOVY

Length: 16min 0sec (960 seconds)

Published: Sat May 06 2023