Hi,

About a year ago, with very little experience in circuitry or electronics I designed the plans for a system by which I could track my 2 cats with a network of RF transceivers in the surrounding fields where I live, and each cat would wear a mini transceiver. (ie, http://forum.allaboutcircuits.com/c...g23.imageshack.us/img23/9639/catdetection.png)
Needless to say, I did not go ahead with actually building it, looking back on it, it was quite an insane and costly idea.

Nowadays I find my cats using a loc8tor (http://www.loc8tor.com/uk/)
Unfortunately, it's very short range and still requires me to play a guessing game in order to locate them, and even then they might not want to come in so I have to return later.

In the last few days I've been researching GPS/GSM products that could serve my needs, and I've come across some very interesting stuff. (GPS to get the geo co-ords, GSM to communicate back the data via SMS)
The big problem here is that these products are rather bulky. There is one very small and attractive product being sold on amazon called G-Paws (http://www.amazon.co.uk/g-paws-00100-G-Paws-Data-Recorder/dp/B009VU82R8) but unfortunately it only records it onto memory and there is no GSM module.

So, my plan is this: I want a GPS/GSM thing that is small enough to fit on my cat's collar (about 2x4x1cm would be ideal, but nothing this small exists), as well as the RF tag for the locator which helps me find them when I'm within 25m of them.
I don't want constant updates on where they are, I just want to send an SMS to the device which prompts it to get the co-ords back, which I can then view on some offline-maps on my phone.

Now it turns out there are lots of products that do exactly this, some designed specifically for pets, and they are all sold in some weird evil version of Amazon that we call Alibaba/Aliexpress.

Here's a list of the best products currently on sale for my needs:
http://www.alibaba.com/product-gs/1180466477/Mini_gps_tracker_for_cat_LDW.html / http://www.alibaba.com/product-gs/999555390/OEM_worlds_smallest_pet_gps_tracker.html
http://www.alibaba.com/product-gs/1269149654/2013_pet_gps_tracker_gps_gsm.html
http://www.alibaba.com/product-gs/804400787/Smallest_GPS_tracker_GPS_locator_kids.html
http://www.alibaba.com/product-gs/819378419/mini_gps_tracker_for_cat_dog.html

The last one is the one that I think would suit my needs best, as I can fix it to the collar length ways so it doesn't get in the way. Currently each collar has a Loc8tor tag fixed to them with sellotape, and I plan to do the same with one of these.

An idea I've had is to strip off the plastic outer casing of one of these products, so I just have the main board and the battery, then I'll wrap them with a thin layer of paper, then cling-film, and finally sellotape so the can be attached.
I think this could help reduce their size while still keeping them safe (and maybe with the added bonus of waterproofing them.

OR I could design my own from scratch, but I highly doubt that it's really doable so I best just stick to Alibaba.

I've been on loads of websites that sell mini GPS trackers but they are mostly overpriced and just resold versions of stuff bought on Alibaba.

My best bet is getting this one (the 'mini_gps_tracker_for_cat_dog' on Alibaba): http://en.toplovo.com/product_list.aspx?id=21&typeid=6
But it costs $90 per unit, plus $23 P&P, plus $9 charge from paypal.
It seems a lot compared to the super cheap stuff I've come across on Alibaba, so I'm a little apprehensive to buy it.

Here seems like a good place to ask, is there a better products suited to my needs than the products show above? I've scoured the internet and found bits and bobs, but nothing I can purchase. Maybe someone on here has some expertise in designing very small gps trackers who can point me in the right direction.

Thanks for reading, apologies for rambling.

 

Awww, I'm saddened to learn that you were unable to continue the project. But, as you learned, it's a tough technological challenge. I'm not aware of commercial products that fit the bill.

You may want to communicate with these guys. They make some good products. I have no idea if they would talk to a DIY inventor, but they might.

Other references that might help:
http://www.consumerreports.org
http://www.kickstarter.com
http://store.apple.com/us/product/H8935LL/A/taggthe-pet-tracker-by-snaptracs-inc
http://www.pocketfinder.com/gps-locator/pet-locator/

 

or just don't let your cats go outside

 

Hi Wayneh,
I just had a look at that, and while it's nice and small, it doesn't have a GSM module on it.
Maybe someone could explain to me how I'd connect a GPS module and GSM module together...

Incidentally I found this earlier:
http://trace.me/techdocs/Preliminary datasheet TraceME TM-202.pdf
A GPS/GSM module. It's light and small and has onboard antennae. But how would I go about programming it and connecting a battery to it all?

 

That's very interesting. I'd open a dialog with them directly if you can.

 

I've just sent them a pretty lengthy email explaining it all and enquiring about the device.

I'm curious though what I need to do in order to make a fully working gps tracker that I can send an sms to and it will send an sms back with its geo-coordinates?

Another interesting little thing, it has a 2.4GHz RF transceiver. I believe that the Loc8tor works at 2.4GHz too, so there's the chance of combining all my needs into this single device... which is pretty cool.
Then again, I have no idea where to start and I'm ignoring the difficulty I'll inevitably face. I mean I have no idea what messages the Loc8tor is sending and what the tags respond with, and I doubt the people who made the loc8tor would be willing to tell me that either.

So, I'm happy with the progress I've already made but I have no qualms about admitting I know very little about circuitry and what is required.
Is there a programmable microchip in the GPS/GSM module? Do I need to create a secondary pcb with all this other crap?

I'm good with code but I'm no good with the real stuff. Could someone list the things I'd need to design this with some explanation?

 

Could someone list the things I'd need to design this with some explanation?

I think there are too many unknowns without more detail about that device. Perhaps they can supply you a detailed manual showing how it works, its capabilities and so on

FWIW, if you succeed with all this, I think a lot of folks would be interested. Cat tracking is kind of the holy grail of pet tracking. A device for a cat is constrained by size (dogs are much easier), weight, and cost (loss of the device is a real possibility). The commercial solutions are getting closer, but just aren't there yet for most cat owners. My 2¢.

 

In the back of my head is the same thought. I'm aware of the demand for small & lightweight GPS for pets, so if I manage to crack it, there's no reason why I shouldn't try and build some more and sell them for a profit.
I'm such a dunce when it comes to electronics though I feel like an unlikely person to do it.
My current field of expertise is in freelance game design which is not going very well right now, so I'm quite open to the possibility of investing in this idea if the opportunity presents itself.

 

I have a respectable amount of experience with trying to locate warm-blooded things via gps and gsm.

The first thing I will tell you is to lower your expectations.

None of them work well (Seriously. None of them.) Thousand dollar tracking devices will do nothing when your cat is underneath a porch or inside the woods. The small antennae do not receive or transmit well and animals prefer places that signals avoid.

Everything is hit or miss, once you accept it then you can start working.

My recommendation is the garmin GTU10. It's a bit big for a cat, but it is properly designed and waterproof. There's also something called the TAGG that is innovative and smaller.

I highly recommend researching those 2 devices before you attempt anything on your own. Cheap tracking devices are cheaply engineered and practically guaranteed not to work. The Garmin incorporates network-based location, low-power GPS and GSM modes, and a few other software tricks that extend batter life. The TAGG communicates with a base station and doesn't activate GPS/GSM until it is out of range.

If you want to go the radio frequency direction finding approach I advise you to do some research into the field. RF DF is... well... a pretty awful way to find things. I doubt you'd ever get enough power and battery life in a small enough package.

 

I've been shown the Garmin GTU10 elsewhere, but it's incredibly bulky and unfortunately my cats are very small, so I can't see any practical way of attaching it to them without making their lives a bit of a misery.
It's not that they're kittens btw, they're just unusually small adults.

I've also looked into the Tagg but it's not available in the UK, and even if I did get one it wouldn't work UK networks.

I find it hard to believe that even a low range GPS device would not work to my standards.
The GPS on my phone is very reliable, and my phone is a few years old and not particularly swanky either. I've tried it indoors, under tree cover, and it's never failed to get my position to within 50m.
The most likely place the cats will be will be in a field or in a small wood (where the trees are young and not particularly tall)

 

Sorry, I haven't ready the whole thread in detail and it's late, but can you not just use the guts from a smart phone? it has a GPS and can send SMSif you can eliminate the screen (I'm not sure that that is possible) then you could cut down on the battery size.

 

In theory yes I think so. But the devil is in the details.

I know of a guy that years ago had is dog carry a cellphone set to auto answer. He could call the dog and listen to his breathing and ambient sounds. Knowing the dog's position, he could decide if the dog might be watching prey (excited) or whatever.

 

May I ask a question? Say you have a microscopic GPS on the cat's collar. So the GPS knows where it is (beyond being on the cat's collar).

How do you then know where the GPS thinks it is?

How does E.T. phone home?

GPS Units. USA company, don't know if they ship to the UK.

 

I've been shown the Garmin GTU10 elsewhere, but it's incredibly bulky and unfortunately my cats are very small, so I can't see any practical way of attaching it to them without making their lives a bit of a misery.
It's not that they're kittens btw, they're just unusually small adults.

I find it hard to believe that even a low range GPS device would not work to my standards.
The GPS on my phone is very reliable, and my phone is a few years old and not particularly swanky either. I've tried it indoors, under tree cover, and it's never failed to get my position to within 50m.
The most likely place the cats will be will be in a field or in a small wood (where the trees are young and not particularly tall)

Trust me on this. I've worked with commercial and military tracking equipment and they fail more often than they work. They do work sometimes, and your described environments seem to imply a higher chance of success. However, you're still playing with finicky technology on an animal that has no interest in being found.

If you know the general location you can use RF DF much more effectively. Transmitters are damn near microscopic these days, and you can use a "Challenge-response" configuration to DF. IE, you have a transmitter that sends out a code, the collar responds, you DF.

 

Trust me on this. I've worked with commercial and military tracking equipment and they fail more often than they work. They do work sometimes, and your described environments seem to imply a higher chance of success. However, you're still playing with finicky technology on an animal that has no interest in being found.

If you know the general location you can use RF DF much more effectively. Transmitters are damn near microscopic these days, and you can use a "Challenge-response" configuration to DF. IE, you have a transmitter that sends out a code, the collar responds, you DF.

For my purposes, I don't need a perfect tracker. If I send a location request and it has no GPS signal, I'll try again later. Right now finding my cats when I want them to come in is a real hassle.
All I want is the luxury of staying in doors and checking until I get a signal, even if it takes 5 tries.
And if I'm able to program the GPS tracker I could make it so if there's no GPS signal, keep checking every 5 minutes until it gets it, then send back an SMS with the co-ords.

Having looked at several other pre-made GPS tracking modules though, I'm pretty sure the cost of the one I found is going to be well over $100.

 

For my purposes, I don't need a perfect tracker. If I send a location request and it has no GPS signal, I'll try again later. Right now finding my cats when I want them to come in is a real hassle.
All I want is the luxury of staying in doors and checking until I get a signal, even if it takes 5 tries.
And if I'm able to program the GPS tracker I could make it so if there's no GPS signal, keep checking every 5 minutes until it gets it, then send back an SMS with the co-ords.

Having looked at several other pre-made GPS tracking modules though, I'm pretty sure the cost of the one I found is going to be well over $100.

This is what pet doors are for. They can come in when they're ready.

 

A few days ago I ordered a gps data logger:
http://www.amazon.co.uk/g-paws-00100-G-Paws-Data-Recorder/dp/B009VU82R8
And today it arrived, and I've been testing it out.

It's small, lightweight and works surprisingly well.
It updates every 10 seconds and can last for several hours of constant usage. If there is no movement it goes into standby.
This is almost exactly what I wanted, except there is no sms communication.
It's a shame, because the tricky part has been solved: it's a working, reliable, lightweight, tiny GPS tracker.

While I haven't used it much, I am able to look at public 'adventures' on the gpaws website, which show the routes recorded by the tracker on a map: https://www.g-paws.com/Adventures
What becomes apparent very quickly is how reliable they are. There are occasional blind spots, but not enough to be a problem.

This is pretty good proof IMO that I don't need some overpriced Garmin monstrosity to reliably track my cat's whereabouts. I can easily imagine the person who developed the G-PawS developing a live tracker from the success of this unit, without adding much weight/area to the tracker.

Poopscoop you should check these out.