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Mobile phone related question

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Hi all

My first post here.

Firstly I know NOTHING about electronics (hence my post). I have an idea for a pet location product.

Put basically, it would work exactly the same as a mobile phone minus the keypad, and screen...

A consumer would buy a collar for their pet (lets say it's a cat); they would then have to purchase or use an existing standard SIM card and put it into the collar.

The owner then sends a specially formatted SMS message to the collar containing a PIN of their choice and an "owners" mobile phone number. This information is stored on the collar within the SIM card (like an address book) and cannot be altered unless the collar is manually reset (again like a mobile phone).

If the cat get's lost, the owner sends an SMS message to the collar containing the 6 digit PIN to activate the collar. The collar can verify the PIN and the number the message was sent from. Once verified, the collar could retrieve it's location (this would be dependant upon the mobile networks but is already in use so I can't see it being a problem) and SMS the details back to the cats owner.

The cat's owner can then use these details to located the cat (or at minimum reduce the search area).

A secondary feature could be that upon an emergency PIN could also be used to activate a beacon on the collar...this could be either a flashing LED or perhaps an audible alert?

This is obviously heavily reliant on the electronics and I want to know if anyone has any thoughts on the viability of this?

Please note, I've been looking around on the web to see if anyone is currently doing this and I've only managed to find something similar for dogs but it isn't mobile phone based. If anyone knows of an existing product, please also post a reply...I want one for my remaining cat :(


Interesting idea.
The problem however comes from when collars are removed, or if the pet is stolen.

Otherwise, if you were able to get in good with the mobile phone companies you might be able to do a triangulation of the pet.

Failling this there is always GPS, coupled with a electronic beacon. If the collar isn't reset at around feeding time it will wait a further couple of hours then begin to broadcast the location of the pet.
Hastle is that if this was successful and became popular, the animal control officers would also have the ability to detect and pick up the animals before you could.

Concept is good, but the technology has to be cheap otherwise everyone who plays around with electronics would be pinching the animals tracking electronics for their own projects. Thus whatever technology is used would have to be very very cheap.

In the interum, you could fit your animal with a harness and place a very small GPS and Mobile Phone in the harness when the animal is wondering outside the house/property. If the animal gets lost, just ring the animal and get the phone to do a call back with the GPS co-ordinates.

How does that all sound for expanding your idea?
Hi townsvillian

Thanks for the quick response!

I understand your concerns regarding the theft of the devices, yes it would have to be very cheap.

I'm not sure how much it would cost but look at it like this:

You can purchase a basic mobile phone for approximately £60? Now, I'd assume that alot of this cost must be down to the display, the keypad and all the internal chips and development needed to run the phone. Every phone works on the same principle and I'd assume that the chip responsible for sending/receiving to the network is probably one of the cheapest parts because by now it would simply be mass-produced by each manufacturer and put into all of their phones.

Essentially, this is all that is needed. Obviously it will need some more internals to store the instructions (what to do when a message is received etc) but past that, nothing else.

I would hope that this could be produced for market at around £30 - £40?

I'm sure there must be some way to ensure that the components can't be reused? - like when you burn a CD and close the session??? (sorry for my lack of knowledge! :))

The harness idea is also a possiblity, although I feel that this could increase the cost, provide opportunities for a cat to get tangled up in a hedge etc and it would be more attractive if it were simply a replacement to a collar (also, potential theives wouldn't be able to instantly know if a cat was wearing one).

The point about the collar being removed: This can't be could have a Delux version with a non-removable collar, but this would add to the overall cost (hence Delux!)

Any other comments?

I work for a group of companies that import, export, repair and sell mobile phones. I'm gonna try and get an email address for one of the developers on monday and pass my comments on to him...I could potentially get the company to look into the idea! ;)


It is an interesting use of existing technology, though I suspect the service providers are not keen to advertise the the fact that cell-phones can be tracked to a specific geographical location, and are well versed in doing so, at the request of law enforcement and thier own anti fraud needs.
Hi Tansis

I'm not so sure.

I have a Sharp GX10 on Vodafone and using Vodafone Live! I can get directions to places based on my current location...they're fairly open about being able to know your location.

Besides, another variation could be to liscense the location side of the requirement to the company that manufactured it?

Just a thought.

I was involved in the development of my companies SMS platform and I know for a fact that our supplier (and most of them) can provide location information to us.


Thankyou for bringing this information, it is hard to abrest of all developemts.
Perhaps a more lucrative application would be automotive, existing vehicle tracking systems are a bit more expensive than a common cell-phone.
Can you tell me how accurate the position fix is ? and how often it updates ?
Hi again

my initial idea was for a pet location collar but after talking it over with my fiance, there's no reason the product couldn't be used for many applications.

As you've already suggested, it could be hidden somewhere on a car (although it could easily be detected simply by moving a speaker around the car...they make odd sounds when near mobiles...probably due to the radio signals?).

You could put the device anywhere really...but I think that if it were sold as a pet locator (especially cats!) then it would hit a niech (spelling?) market. Alot of cats tend to go missing (as is one of mine right now!) and many are never found. If something were on the market for around £30 that could locate my cat within a radius of 100meters I'd buy it!

In answer to your question, I believe the accuracy is 100meters.

From memory, when I used the directions facility on Vodafone Live! it had a disclaimer saying that it was accurate to within 100 gave me my current postcode (I've tried it from different locations and it works well.

FYI: I live in Somerset where the network masts are few and far between. I would have guessed that the triangulation would be better in cities?


Sorry to hear about your cat, I hope it returns safely.
The device you propose has far more scope than a simple niche market.
I have some close links with the haulage industry and suspect they would be very interested in the ability to track a vehicle to within a 100meters, provided it could be done cheaply enough, accountants are a mean bunch.
Real-time feed back may prove prohibitive in terms of cost , but could the service provider give a list of time and locations at the end of the day/week?
Sounds like fun, yet strangely disturbing.....

:shock: :lol:
Just a couple of points w.r.t. location services from operators offered to the public. They are based on Cell-ID, i.e. the cell (basically the antenna) your GSM is currently registered too. There is no triangulasation involved. This is more than enough accuracy to find a hotel or restaurant or to play the games from that Guardian link, but since cells can be up to 35km in diameter, it is no good for homing devices. Of course, in cities there are micro-cells which greatly improve accuracy – important for the ‘city-based’ games (cells can be as small as 300meters) – but cats hardly ever go astray in cities (city-cats are kept inside for obvious reasons).

On top of that, your Cell-ID is not even guaranteed to be the antenna that is closest to you. Older or cheaper GSM-phones will lock to an antenna when powered up, and then keep using this antenna for as long as possible, even if stronger antenna’s are already available. It is only when the connection to the original antenna drops below a certain pre-defined threshold, that a handover to a better – or “closest” – antenna occurs. This concept saves battery power since the cellphone is not always scanning frequency bands for the ‘hottest’ antenna, but it also saves computing power which is important to keep the component cost low. Modern - and more expensive - GSMs however hand over as soon as a better antenna is found.

Then there is true location gathering using triangulasation (or whatever it is called). This can only be used by the emergency services or by the police trying to find criminals (or stolen cars equipped with a registered GSM alarm), which uses the input from more than one antenna (as opposed to just giving the ID of one antenna for the commercial applications). I have no idea on accurary, other than knowing it works :). There is even a special type of SMS message which can be used by law enforcement agencies: type 0 (subset from class 0). When you receive such an SMS, it will not be shown on screen or stored on SIM, but it will be acknowledged to the network, thus reveiling your location. The criminal obviously does not even know he was being tracked.

As for tying a GSM-based homing device to your cat: I wish you much luck in trying to tie your cat to a mains outlet once a week for two hours straight to recharge the batteries :lol: .
35Mhz animal tracker

Hi again,
I just remembered about a friend of mine who was studying marsupials at Uni.
He had about 5 or 6 35Mhz animal trackers which allowed tracking by a portable receiever and antenna from almost a km away.
It was a purely analogue system. The unit was very small (could fit in a collar) and gave a month's battery charge.

There are a few commercial enterprises which this tracker system can be purchased from.

If the signal was able to send a digital serial code through the analogue system, then each transmitter would have it's own serial number.
The key is to keep the thing analogue as there is less problmes with interferance (ie. you will get a signal even in bad conditions, as opposed to digital where you either have signal or you don't.'s still missing :(

Hi all

Thanks for all the interest and information.

Jimbo: You seem to have a wealth of knowledge here so I'll assume that you know what you're talking about...but how then does Vodafone give me my current postcode or a reading such as "you are 3km south-west of somewhere (insert place name)"?

Also, regarding the charging aspect...I thought the collar cold be sold with 2 batteries and a charging station then simply swap the batteries around once a week (or when the collar sends you a sms telling you the batteries are low ;))

Townsvillian: not sure about this. The idea around basing it on a mobile phone is because it can then use current technology to trace a cat almost anywhere (not within a given range). Also, it can be purchased as a standalone product that anyone can use via their mobile (rather than having to buy a secondary piece of kit - namely the receiver.

Cats can walk for miles (so I've been told) and so a radius of 1km sounds very restrictive.

It's true that the digital signal may be an issue but then again, it can't be that bad given the number of digital mobile phones currently in use? :)


Hi all

Forgot to mention, does anyone have any knowledge of mobile phones?

I can look into the location information available from networks but as I've previously said, I know absolutely nothing about electronics!

If the information is available from the networks then I'm quite serious about building a prototype...if anyone knows how!!!!!! :D


She's home!

Hi all

I just wanted to let you know that I have my cat back. :)

A man in my village had spotted her near the church yesterday and gave me a call. I went straight over and within a minute of calling her name she appeared!

It's a shame that the SMS collar idea isn't something that is available though!

I've looked into traking collars for cat's and they start and around £200 and go up!

I'm determined to get something...if only for my own cats.

Thanks for all the feedback guys...I'll keep you posted of developments with my own idea. ;)


tracking your lost cat

:D hi there wayne, i enjoyed a lot to all the response to your problem, your problem is what device to attach to the collar of your pet without necessarily attaching a cellphone. you also mentioned that you work on a company that repairs and imports cellphone. Here's my two cents advice, use only the circuit board, the sim holder & the batt holder. look for the cheapest cellphone circuit board. :D
Hi, :D

A lot of the information that has been talked about in the above post's is already available i.e the tracking of stolen vehicles using GPS. Lo-Jack in the USA and Tracker in Europe.

Also when it comes to the cost of phones and tracking devices, and you see the retail value of these products at £60+. Then these are not the true cost's of these devices! The true cost's are closer to £200+. The reason that you see a price of £60+ is that the companies make there money back on these devices by the cost of calls and SMS. Do you really think that it costs 12 pence or greater to send a SMS? This is also why now that more and more handsets are being given away free with contracts when you sign up for a year! :shock:

Ian 8)
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