Let's talk about RTK (it's coming soon!). Does it help in anything apart from increasing precission?

[DroneCalzone]

Hi,

as you probably know H520 RTK will be available any day now, so I thought we could talk about why do we actually need RTK? I read some stuff online, but I would like to confront that with practicioners, people who know from experience how it works and how it benefits drone work.

How it works? I'm just going to present how I understand it works, and I may be wrong - if so, please correct me!

We have a base station that we deploy before flight. The ground station has a super-precise GPS that gathers GPS data over time and that allows to pinpoint the location of the base station with centimeter precission. The copter in flight is in communication with the base station (on what frequencies/bands?) and sends its own GPS and accelerometer data to the base station. So now we have 3 sources of data: Base Station (BS) GPS data, drone GPS data, and drone accelerometer data. Base station uses the data to compute the copter's precise location relative to the BS. BS's location is precisely known so therefore also the copter's precise location is also known. Is that right?

We gain in GPS and geotagging precission for surveys/mapping.

But I also read a lot that RTK helps in situations with magnetic interference and low GPS visibility (for example - in inspections under bridges or in flights in between tall buildings). Actually even Yuneec writes that in the marketing materials.
I think (?) I understand the logic behind this: the BS gets a very good GPS signal (better than the drone's signal), and if the drone's GPS signal is weak, then the drone can use the location of the BS as a reference point, and summed accelerometer data to calculate its position, instead of using its own GPS?

A for magnetic interference I assume that the same thing happens, but with the summed gyroscope data..? I'm just thinking out loud here.

 

[Snagglesworth]

From my understanding rtk is used to cancel out GPS errors.
You set up the Base station. The Base station is in a fixed position so it's GPS location never changes. With any GPS system you will get variations in the position being registered by it due to atmospheric conditions (GPS drift) but because the Base station is in a fixed location it can calculate the difference between where it knows that it is located and where the GPS is saying it is located at that time. The Base station then sends the difference between the two locations to the craft which then uses the difference between the signals to accurately work out where it's GPS location is. (Real time kinematics)
There is also ppk (post processing kinematics) in which the differences between Base location and GPS are recorded to file with time stamps and then the corrections are made to the crafts GPS position during the processing on the pc.

 

[PatR]

For the record, position accuracy improves even more when two GPS ground stations are referenced by aircraft GPS. This RTK thing is nothing new, it’s a method that has been in use by UAV’s for at least 15 years

 

[Phaedrus]

For the record, position accuracy improves even more when two GPS ground stations are referenced by aircraft GPS. This RTK thing is nothing new, it’s a method that has been in use by UAV’s for at least 15 years

But new for the lower end of the sUAS market. Not all us get to fly the Global Hawk ?

 

[RPR]

For the record, position accuracy improves even more when two GPS ground stations are referenced by aircraft GPS. This RTK thing is nothing new, it’s a method that has been in use by UAV’s for at least 15 years

That one time at band camp.....

 

[PatR]

I still have considerable proof from back then showing .2m RTK accuracy. You won’t get to see it but that’s been improved upon since then. However, someone browsing YouTube might observe part of a GPS set up if they were observant. Pretty hard to hook a thin rope with a wing tip without being positionally accurate. Even more difficult on a moving ship...

 

[RPR]

Here’s where Yuneec RTK stands as this moment. If we step back into the real world of the public sector and the practically use of RTK, it is a game changer as proven by DJI.

Yuneec can tip the scales in the market, due to DJI’s ridiculous, and expensive RTK package.

The H520 is not making a lot of sales this is evident, because we hardly hear, and see on the field.

I am hoping and patiently waiting for a concrete review Yuneec RTK review. Because if Yuneec delivers, this can potentially end DJI’s RTK package.

In the civilian world.. SwiftNav were the first to provide a workable package for heavy lifters, before the ease of aerial mapping, and 3rd party vendors providing an application that is available for everyone. DD, PIX4D, MapsMade Easy... etc..

Yes, this is not new. RTK GNSS has been around, but DJI open the Pandora’s box. Before the apps, I was already mapping that is why I find manual mapping rewarding.

Now let’s get back to reality and @Snagglesworth answered the OP of its use and purpose.

Now the waiting game begins, and I am hoping to hear great maiden flight reviews. Because in all honest.. A Yuneec sUAS belongs in every worksite, and not that over priced ugly RTK Phantom.

 

[arruntus]

Really the pandora box was opened by the development and lowering of the costs of the RTK L1 by u-blox with their developments and is what really broke the market, which have achieved that we can get an RTK at the price we talked about. Then companies like Emild or Drotek, among many others, brought out optimized and integrated systems and these are the ones that have made that DJI has brought a solution to the market let's say available to the masses in a simple way and without technical knowledge. Drones with RTK L1 and L2 have been selling for a long time, but the price is prohibitive. However, thanks to u-blox, which has been able to develop products with quality and much cheaper, has allowed it to reach many more people.

I have pending to mount one of these RTK, in my case a Drotek, it will be interesting to see how it behaves and as it does the one of Yuneec

 

[DroneCalzone]

From my understanding rtk is used to cancel out GPS errors.
You set up the Base station. The Base station is in a fixed position so it's GPS location never changes. With any GPS system you will get variations in the position being registered by it due to atmospheric conditions (GPS drift) but because the Base station is in a fixed location it can calculate the difference between where it knows that it is located and where the GPS is saying it is located at that time. The Base station then sends the difference between the two locations to the craft which then uses the difference between the signals to accurately work out where it's GPS location is. (Real time kinematics)
There is also ppk (post processing kinematics) in which the differences between Base location and GPS are recorded to file with time stamps and then the corrections are made to the crafts GPS position during the processing on the pc.

So accelerometer data is not taken into account? I thought that's what "kinematic" was referring to.

Also - what do you think about usefulness of RTK for inspections in difficult areas with low satellite visibility or magnetic interference? Does it help?

 

[arruntus]

So accelerometer data is not taken into account? I thought that's what "kinematic" was referring to.

Also - what do you think about usefulness of RTK for inspections in difficult areas with low satellite visibility or magnetic interference? Does it help?

Real Time Kinematic or satellite kinetic navigation in real time. That's what it's all about. It indicates that the calculations are done in real time. With PPK (prost processed kinematic) the data can be processed later. In other words, it processes the information in real time or not.

It also helps in the sense that apart from satellites, you receive information from a ground base that you can make have direct vision with the drone.

 

[RPR]

Real Time Kinematic or satellite kinetic navigation in real time. That's what it's all about. It indicates that the calculations are done in real time. With PPK (prost processed kinematic) the data can be processed later. In other words, it processes the information in real time or not.

It also helps in the sense that apart from satellites, you receive information from a ground base that you can make have direct vision with the drone.

What is your assessment and prediction for this new H520 RTK?

 

[arruntus]

I don't dare until I see reviews. What is clear to me is that from the videos I have seen at the fairs, the Yuneec representatives have been too cheerful in their statements. Or so I think, if I'm wrong, better for everyone. They have given too optimistic data, it is clear that their job is to sell, but from selling to lying, in my opinion, there is a very big stretch.

It is true that if they have taken advantage of the latest developments, the results can be very good, in general they are already very good in almost all models in the market giving between 2 and 3cm. Below 1 cm, as some have said, being an L1 I see it difficult, I'm not sure, in L1/L2 yes, but with L1......

In this matter I am more concerned about the time that the base, connected to a network, takes to establish a fixed and stable point. Sometimes you get bored of waiting and that's why it's better if they can give you a given point and just introduce the base coordinates, speeds up the work a lot. If the setup time is fast and gives a resolution of 2-3 cm can be very good, because it would play with the price, which despite being cheaper than DJI, is still too high for what you can buy elsewhere. The integration and comfort is worth money, but I don't think so.

 

[PatR]

RTK time solutions can be extremely fast when set up correctly, but long distances or signal interference between stations impact time solution. It’s possible to maintain extremely precise position updating at distances of at least several miles even when an aircraft has a relatively fast closure speed with a base station.

When GPS signal is weak or interrupted all bets are off though.

 

[PatR]

But new for the lower end of the sUAS market. Not all us get to fly the Global Hawk [emoji2957]

Me neither[emoji6]

 

[RPR]

This a new technological era. I’m not going to step on the clutch as of yet, and that it’s a win for Yuneec. I will soon be traveling back n’ forth from Hawaii to here in the mainland soon, and in need of a workhorse in the near future.