Where’s The Cat? Locating Your Moggy Without Eating Batteries

Where the Hackaday Cat goes when she steps over the threshold into the wider world is a mystery, she reveals her whereabouts strictly on her terms and would we suspect be very cagey were we able to ask her about it. [Andy C] however has a need to know where his cat is spending her time, so he’s made a GPS collar for a bit of feline spying.

There are commercial GPS collars for pets, but they all share the flaw of extremely limited battery life. His challenge then was to create a collar that delivered the required pinpoint fix alongside a battery life measured in months. The solution was a combination of a low-power miniature GPS receiver and a low-power PC microcontroller hooked up to an FSK radio whose frequency he doesn’t give but which we suspect is probably the usual 433 MHz. The collar remains in low power mode until it receives a call on the FSK, at which point it wakes up, gets a GPS fix, transmits it, and returns to sleep.

The summary links to a series of posts which provide an extremely detailed look at all aspects of the project, and go well beyond mere GPS trackers for a cat. If you have an interest in low power devices or antenna matching for example, you’ll find a lot of interesting stuff in these pages. Of course, if all you need is a GPS tracker though, you may prefer a simpler option.

38 thoughts on “Where’s The Cat? Locating Your Moggy Without Eating Batteries

  1. Hmm, to track my cat with a 433 radio it would either need to grossly exceed the power regulation or have a Yagi fitted with some sort of point at home mechanism on it. :)

    I have seen him well over half a mile away.

    1. 433 goes quite far and is used in Germany for fox hunting. 10mW, 15mW or 25mW is allowed depending on country but the transmissions have to be intermittent, like in this application. Buy a Chinese garage dor module, they stretch the law to the “limit” and put a 2 or more element yagi on the receiver and you get 5-10 miles range (if your cat stands on its hind legs on a hill top).

  2. or just use the APRS network with a low power radio that also only wakes up when recieving a strong enough signal on the tiny antenna to be sure that the transmission the other way would be strong enough

  3. Reading for a few minutes, i found this part of the text: “I’ve written some basic code in the PIC that tells the CC1125 to output a Continous Wave (CW) at 868 MHz, to allow me to take my measurement” – So not 433, but 868 MHz.

  4. Free range cats and collars are probably not the best idea.
    They can hurt themselves when they get stuck with the collar on/in something. Like a hole in a fence or something.

    1. ive found that if a cat doesn’t want to wear a collar they will find a way to loose it in the woods. this is especially true of those break away collars, which seem to disappear within the first week of use. i certainly wouldnt want there to be any expensive electronics in there when it happens, unless of course it transmits its position.

    1. Reception can be as low-power and as low duty-cycle as you need. It doesn’t need to be “continuous” at all, you just make the transmitter side send it’s ‘wakeup’ signal long enough that the receiver is guaranteed to have woken up at least once to see it.

  5. Another way to track kitty without weighing it down is to attach a low-powered ultrasonic beacon like a belled cat. Then send up an autonomous quadcopter (AQC) drone with a tracking ultrasonic receiver to go look for kitty. Just make sure operational frequency is well above 45 KHz as kitty can hear up to that frequency.Or if you can’t afford a AQC then place a bunch of field solar powered IoT’s throughout the neighborhood to report ultrasonic hits back to your website. Then it reports back to a website it’s pre-assigned fixed location. Disguise the IoT’s like the animal poop (or a rock) VHF transmitter seismic gadgets used to report North Vietnamese troop movements to the Americans during the VNW (i.e. Operation Igloo White). This is to stop people or animals from messing with your IoT gadget. (Or some creative variation on this theme)

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