Need Help New RTK system. "Reach"




Bartman

Welcome to MultiRotorForums.com!!
so the article is about the availability of the new antenna technology but the integration into an affordable flight control system hasn't happened yet?
 

Riche

Member
Had me thinking as well. Unless I missed something it said it was an RTK unit... and it needs a quality antenna to achieve the 2 cm accuracy. But something made me think it is a flight controller.
The other lingering question was range with the RTK connection between the second controller. If you can use local NTRIP service a simple cell connection would allow for practically unlimited range. However in my experience cell connections can be a tricky from time to time. This was very interesting video to watch.

In the meantime I'm still trying to figure out how to turn my dromida around and fly it back to me without hitting the ground... It is like having two left hands. lol
 
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ProfEngr

Member
Return-path flight is a mess for me as well. At some point I'll have to buckle down and learn, but for now I just try to keep the red 'eye' facing me.
 

JoeBob

Elevation via Flatulation
As I understand RTK, it's like triangulation. With your base station being much closer than the GPS sats, you can get a solution with 2cm of accuracy instead of 2 meters.
A competing system, Piksi ( http://swiftnav.com/piksi.html ) uses 3DR radios for communication.
The discussions for Piksi emphasize that you must have a clear view of the sky.
The reach system uses NeoM8 GPS which gets much better sat reception than the Neo6
Reach is $570, Piksi is $995.
Both systems allege compatibility with Pixhawk flight controllers.

I'm going to get one of these systems when my finances allow. I just don't know which one, yet.
 

Riche

Member
You are close, but the proximity to the base isn't as important as the connection to for the real time process to provide the accuracy. We call it base & rover in surveying. So the rover can only report a 2 centimeter or sub centimeter accuracy if it has a connection to a base to process it's horizontal and vertical location. The connection method is the tricky part. There are a few methods. But in the very beginning is was a radio connection. Since then cell connection has come into play.
You are right about satalight view.
No mater what type GPS you have full view is very important.
The RTK method is the only way to get 2cm or more accuracy.
 

Riche

Member
Just ignore some of the things I said. I missed what you were saying about the reach having the better board.
Do you know what type of radio connection reach has?
 

JoeBob

Elevation via Flatulation
Nah, 'triangulation' is probably not the best analogy.
Let's try this:
Single GPS receiver is like walking a 2 inch wide plank while trying to place a full glass of water on a 3 inch diameter post in a room lit by a strobe light. The plank is the earth rotating, the glass of water is your MR, the 3 inch post is the location you desire, and the strobe light is the GPS satellites refreshing. Since every element of the equation is moving, 2 meter accuracy is pretty good.
RTK adds a base station receiver that is like adding a wall for you to brace your other hand against. The base station reconciles multiple fixes over time to establish a precise present location, and predict future location trends (on the rotating planet surface). Using this dead solid reference point and the kinetic measurements of the rover unit, RTK claims 2cm accuracy.

Since the base does not directly measure direction and signal strength of the rover, my triangulation analogy was missing a leg.

What else am I missing?
 

Riche

Member
I think you have a good understanding, I just wanted to point out that the base doesn't necessarily have to be "close" as you mentioned.
Its all about the connection of the base to the rover.
For instance the drone (rover) will only have a 2cm accuracy within the limits of the 3dr radio signal range. So yes the base will have to be close.
However some of the radio equipment we use has radio signal strength that will allow the rover to be several miles away.
 


Riche

Member
Lol
Yeah, I think I read that the range of the 3dr radio was about 300 ft. without a better antenna.
 


Bob Denny

New Member
Good heavens, this looks like it is self contained and able to provide RTK level accuracy in dynamic environments ("no realtime link"). If this comes true it will be a game changer. It will also give lots of countries the ability to deliver munitions with accuracy formerly available only to encrypted P-code GPS.
 

Riche

Member
It didn't look like centimeter accuracy. But with out a reference station it is still extremely accurate and impressive!!!
 


Riche

Member
Oh ok, that was with a base.
I had a local base set up at our office for a little while with old equipment. We have since moved on to a local NTRIP network.
I have mixed emotions about using a cellular connection to a base station as opposed to a radio.
 

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