REACH with return to home function (to deployment boat)

Hi ,

I’m currently working on a project where I have an RC boat, combined with a reach module.
I would like to make it possible that the RC boat can return automatically back to the deployment spot (sort of a ‘return to home’ function), in my case a small motorboat.

Would it be possible to make that happen?

For example by working with a Reach module on the RC boat, a Reach module on the small motorboat and a Reach module on shore as Base station?
And than combining it with the Pixhawk autopilot?

Thanks ! Daan

The return to home feature is supported by APM, so it should be no problem. Just configure Reach to work as an external GPS and your boat will take advantage of the precise coordinates.

Thanks for the reply!
Is APM a better solution than Pixhawk in this case, according to you?

That’s not what I actually meant, sorry for the confusion. I actually wanted to say the ArduPilot, meaning the software.

No problem! Thank you for the clarification!

I had one other question…
I read somewhere that the Tallysman antenna doesn’t need to point straight up…
Is that correct? Can we just position the antenna in any direction, for example 45 degrees sideways on the rover?

Hi Daans,

Best results of Rover antenna is straight up. Ideally, placing the antenna on a gimbaled platform would be best to get maximum satellites, but this is not usually practical. The ground plane below the antenna will block reception and create additional multipath problems. Also, the gain patterns are usually optimized for vertical antenna placement.

On an RC boat, this may present a problem with sailboats as I think the boats tilt significantly from vertical. The sailboats tilt significantly and change with direction.

I have had some tracks, however, that seem to work with a tilted Rover antenna. The more satellites you use, the better results I would expect. Motorboat would be better platform,

I’m not very familiar with the camera stabilization platforms for drones. Maybe someone else can suggest something to keep the antenna vertical under large platform tilts.

Good Luck

Hi Richard,

Thank you for the reply !

My problem is that I want to make a robust system, so that means as little pivoting points as possible…
Unfortunately I don’t yet have the budget to test the Reach system, so I’m currently trying to find as many answers as possible.

Do you have any idea what the difference in accuracy would be if I placed the antenna in an angle of 45 degrees?
The RC motorboat is fit with a stabilisation system to prevent it from tilting too much.
And I will mostly use the Reach module to calculate it’s speed and direction!

As I mentioned before I will also use a Reach module on a big boat, but that one will have an antenna that points straight up, and the position of this boat is more important, because I want to implement a Return to Home function on the RC boat as well!

Hopefully you can answer all of my questions

Kind regards, Daan

Hi Daans,

Although my career consisted of communications and navigational engineering and maintenance of systems both air/space and underground, predicting performance is often very difficult. Testing is often the best solution. One thing will probably come true. As more satellites are available, performance will increase.

I have seen some tests that show improvement in future for L1 systems of FIX at 40% for GPS only, approx. 70% GPS +Glonass, and 90% GPS + GLO + China.

As you mentioned, tests cost time and money, so you may become the one to lead this area for the forum.

I wish I could provide more answers, but Emlid has been generous to provide this forum, and I hope you can get. your answers here. If I get a chance, I may try to run a few tests to get a general idea of results. At the moment, I think Reach is receiving some expected upgrades, so I’m looking to see those results first.

Tallysman is probably a better source for information on antenna tilt. They provided the antenna to this project. Phase changes of the L1 carrier with tilt would probably degrade accuracy. However, there is so many routines in RTKLIB and branches to compensate for cycle slips, etc. that I can’t make an intelligent prediction.


1 Like

Hi Richard,

Once again, thank you for the quick reply!
I understand that very well, predicting performance is ofcourse very difficult.

I’ve tried to contact Tallysman for more information, maybe they can help us !

Thank you for your information!

Hi again,

By the way, your interest in the return to home function may very well be useful as drone regulations get legislated.

In the US, there has been talk of mandating this function in all hobby drones that lose control from the drone operator.



I contacted Tallysman and they also said tilting the antenna on the rover may result in loss of accuracy.
But having the base station in a proper upward orientation would definitely help mitigate the impact of a tilted rover antenna. It would reduce the impact of low elevation satellites.

They also mentioned using more satellites would improve accuracy.