RFID-detecting pet door

We have recently had a raccoon – or some similar beastie – coming into the house at night.  We know this because in the morning the kitchen cabinets at floor level are all open, and marshmallows or chocolate have been dragged out and bestowed with small tooth marks.  The cat – bless his peaceful, kindly soul – is of no help defending the castle, and probably invited the scoundrel in.

The cat door, a simple flap that keeps wind and sufficiently large animals out, is certainly the point of entry.  Evidently we need a more specific technology!  Cats are routinely implanted with a “microchip” to ID them if they get lost.  A door that would only admit specific RFID tags would be perfect, and I did some research and found that there is just one RFID reading product, the SureFlap DualScan, has a good reputation for keeping raccoons out.  (Aside: why is that Amazon product title in French, like parfum de fantaisie?)

But!  The cat couldn’t reliably trigger it, even when forcefully jammed into it (neither of us relished this test).  I contacted SureFlap and they sent a “range testing kit”, which is an RFID tag attached to a cardboard ruler.  But I noticed that it is extremely good at reading in the exact position of the kit, and very bad with any change of orientation whatsoever, or even removing the cardboard:

I look forward to hearing what SureFlap has to say.  In the meantime, I’ve been baring the pet door each night with a bit of Dremel-modified angle bar, and have had no evidence of intrusion so far.

IMG_20150723_181834 IMG_20150723_181808

Edit: SureFlap got right back to me with a clear explanation of why the cardboard matters:

The issues that you are encountering in your video are a bit of a misunderstanding.  The way that the SureFlap works is that you will notice on the underside of each of the tunnels are two plastic lenses.  These lenses have an infrared beam of light which bounces off the bottom of the tunnel, this beam of light is how the product is able to run off of batteries.

As you can see with your tests – until you disrupt that beam of light, the SureFlap itself will not turn on to “read” the microchip.  Which is why you get such differing results when you remove the microchip from the range test kit.  The kit itself does not in itself increase the ability of the SureFlap to read, however the design allows it to be shaped like a cat, and thereby break the beam of light – turning the SureFlap on – which then activates the reader, and you get a range of 28cm which is an excellent range.

I had noticed the lenses, but assumed they were mechanical fasteners.  Here is what they look like:


Next step: attach the RFID tag from the test kit to the cat to see if it works better than the implant…


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: