Advice on GPS animal beacon

Hi there,

I've been playing around with this idea of having a GPS beacon on my sheeps for easily location during their summer time in the mountains. We have the last years been testing out a GSM system for sending GPS positions via the mobile network (GSM / GPRS). Bue sadly due to weak/no mobile signal in many areas, the results hasn't been so good. In many instances the GPS positions doesn't get sent, and therefor the system isn't working as good.

That's where the idea of a GPS beacon comes in, which I wonder might outperform the GSM system due to the lack of signal in these areas. The area is pretty flat, but got some small mountains here and there. The total distance / length of the area the sheep is grassing, is about 10km wide (6.2mi). The duration of the time grassing is about 3 months during summertime.

I've been looking at some long distance beacons and it seems 10km is doable. But maybe that's in flat area with no obstacles (like trees small mountains etc).

So what I'm trying to figure out here, is this doable, and can it be done for lower the price of the GSM system (which is about US$100 per unit).

Just to give a summary of this:

  • Track GPS position on each sheep (about 50 sheep in total).
  • Distance to sheep, up to 10km.
  • Position tracking should occur once a day, or twice, but preferably when we wish to get the location.
  • The tracking duration should be about 3 months.

I know this might be a lot, but hope it makes it clear of what I want to accomplish here.

Hope somebody could give some guidance and recommendation on what they think would be best.

It sounds like a really interesting project

Start by looking at https://en.wikipedia.org/wiki/Geocaching

These guys use relatively simple transmitters - usually without the location data, but that can be added for your project.

What you have to solve, is either (1) an omni-directional high-gain antenna with enough RX signal level to receive from all directions, or (2) a rotatable 'directional' antenna to sweep your fields as needed.

(1) would allow your transmitters to send infrequently - to save battery life (2) would require almost continuous transmission - to be heard when each 'sweep' passes. Option 2 - also allows for lower power transmitters than (1), but they need to be on more time...!

Thanks for the suggestion regarding Geocaching. I don't however quite understand the connection between those two (geocaching and GPS positions on moving sheep), but maybe I missed the point? I thought geocaching were packages hidden outside by others to find - but not something that would actually send any signals for us to trace down (unless you know the location coordinates of course).

But having a powerful antenna to receive signals sounds doable, but how big does this have to be in order to receive from 10 km away? Any idea?

To take this even further, what I also had in mind was the use of a drone to help me locate the sheep. I got a drone who can fly around an area of about 1-2 km, and it would be cool if the drone could receive the signals and coordinates from the GPS transmitters on the sheep nearby. We could then use the coordinates to locate the sheep more easily.

The idea behind the drone is to rise high up in the air and circle the area (as far as it can) - this giving it altitude and should also give very good signal strengt compared to standing on ground.

So what is needed is:

  • High gain antenna (preferably mountable to a drone)
  • Transmitter to mount on sheep
  • Receiver to log the coordinated (must also be on the drone I guess - or maybe it could send some signals to a remote somehow)
  • A good battery for lasting 3 months (but if I understand you correctly, with an omni-directional antenna, the battery on the transmitter could be extended)

Overall, creating such a system is an [u]extremely[/u] challenging project for a hobbyist, or more likely, in the "entertaining fantasy" category.

Making any sort of GPS radio tag that can operate unattended for 3 months is very difficult, and you have the added conditions of mounting it on an animal in such a way that can withstand a lot of abuse and environmental insults.

The receiving equipment is also nontrivial -- high gain antennas are highly directional.

I suggest that commercial solutions are worth what you have to pay for them. Wildlife biologists do this all the time, so that is where to start looking. Also consider satellite trackers, like the SPOT Trace. http://www.findmespot.com/en/index.php?cid=109

Thanks for the response. Although I am a hobbyist / newbie when it comes to this, however I'm also an experienced programmer. So when it comes to working out a solution for how the software needs to work, that wont be a problem.

What I'm looking for here are some shared knowledge when it comes to building something like this in terms of hardware needed. Thats my lack of knowledge.

I know there are other services that offers way better solutions than I can build, but isn't it what this forum is all about - discussing and finding solution for building something great?

And overall, it would be a fun and challenging project which would give a lot of knowledge around this area. So why not at least give it a try.

The software is the least challenging part of this project. That has been done countless times.

There are few radio professionals on this forum. I suggest to go to EEVBlog for advice.

Thanks jremington.

I'll give EEV a try, but from what I understand, Arduino isn't the obvious chose for this kind of project then?

Arduino and ATMega processors are perfectly suited for this project, although you would make a custom board optimized for low power operation. The radio, GPS, power supply and enclosure are the real challenges.

Alright, thanks for pointing that out jremington. I'll do some digging around.

For an example of an ultra low power Arduino radio sensor (short range), check out this project blog. Lots of other great tips on that site, too!