Posts 6 comments on tl;dr complete build summary

tl;dr complete build summary

There are a lot of posts to trawl through in this blog if you’ve not followed it from the beginning. Hopefully this summary makes everything a bit clearer…

The first thing I did was to have a look at other cat tracking products on the market.  I found that they all have a big flaw… battery life.  I wanted GPS level accuracy and a battery life measured in months.  Nothing on the market offered that, so it was down to me to design it!

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Posts 3 comments on Long Range Communications with the CC1125

Long Range Communications with the CC1125

I’ve now written enough code for the PIC on the CatTrack base station such that I can begin to test it!

I’ve already tested comms with the CatTrack collar, using a development board instead of the base station.  Read about that here.

Unfortunately, when testing my base station I found that it was nowhere near as sensitive as the development board – the base station was getting CRC errors whilst the development board was still receiving the signal fine.  After a small bit of investigation I found out why.  The problem is all down to the fact that I want to use the CC1125 at the lowest baud rate (300 bps), and consequently a very narrow receive bandwidth (3.8 kHz).

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PCBs, Posts 0 comments on Base station PCBs have arrived – time to solder!

Base station PCBs have arrived – time to solder!

Well, the boards actually arrived several weeks ago, but I’ve only just got round to doing the soldering.  As ever, I’ve ordered all my components from Farnell in the UK.

All of the passive components I’ve used are 0402 sized (0.5mm by 1.0mm).  The advantage of components this small is that you can squeeze a lot into the RF sections of the board, most notably at the output of the CC1125.  This decreases board size and improves the RF performance.  You can go much smaller than 0402 – 0201 is the next size down, followed by 01005 – only 0.2mm by 0.4mm!  Getting decent performance out of an inductor or capacitor that small will be difficult, so it’s a tradeoff between size and performance.

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Posts, Schematics 1 comment on CatTrack Base Station Schematic

CatTrack Base Station Schematic

Now that the CatTrack collar is working, I’ve been designing the schematic for the base station.  The base station is the handheld unit I’m going to use to communicate with the collar to work out where the cat is.  Currently I’m using a CC1125 development board.  More about that here.

The idea is that the base station will mostly live at home, perhaps in my loft (to get decent range) and I’ll be able to communicate with it from my living room via Bluetooth from my laptop.  It should also be portable because if Buttons goes miles I want to be able to take the base station out and about to track him remotely.

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Posts 0 comments on What’s CatTrack?

What’s CatTrack?

Unsatisfied with the GPS trackers available on the market, I decided to design my own.  This site follows my component-level design and build of an ultra-low-power wireless cat tracker.

A few years ago we got some cats – Buttons and Turnip!  Buttons is the big tabby cat and that’s Turnip, below.

I would imagine that every cat-owning Engineer has at one point or another wondered about either buying or making a tracker for their cat so they can see what he or she gets up to after they jump over the garden wall.

Turnip isn’t like most cats.  There’s no need to make or buy a tracker for her because she hasn’t left the garden in 3 years.  Well, she did end up in next door’s garden once, but I got the impression from the noises she was making that it was incompetence that caused her to end up there, rather than a desire to be more than 10 feet away from her bed.

Buttons however, would benefit from a tracker.  Although he doesn’t disappear for days at a time like some cats, he is often nowhere to be seen, only to turn up a few hours later covered in cobwebs or some other kind of grime.

As you can read in my About Me page, I’ve got a fair bit of experience with electronic design.   It’s been my job for the last 10 years.  None of the cat trackers on the market fitted my needs (as I’ll explain in a separate post) so I decided to design and build one that’s much better than anything you can buy! (hopefully…)

I’ll be doing a component-level design, from schematics, through PCB design and ultimately casing it all up in a case appropriate for Buttons to carry around with him.  I’m sure there will be second revision too, to mop up all my cock-ups from the first revision!

This blog is partly a way to force myself to finish the project.  I wouldn’t want the 3 people reading this to be disappointed would I!

Posts 1 comment on Why not just buy a GPS cat tracker?

Why not just buy a GPS cat tracker?

The simple answer is battery life.

My requirements for a cat tracker are:

  1. Very long battery life (around 3 months).  I don’t want to be changing batteries all the time.  The one day I forget to change the battery will be the day when Buttons decides to go an investigate next door’s shed, I know it.
  2. GPS-level accuracy.
  3. The ability to remotely find out where your cat currently is, allowing you to find him if he’s lost.
  4. Small enough and light enough for a cat to carry around (obviously!).

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