Computing stuff tied to the physical world

X10 RF reception

In Software on Apr 20, 2010 at 00:01

One more decoder, a home automation protocol this time – a X10 RF transmitter:

Dsc 1342

That’s a Marmitek SS13, sending out over 433 Mhz (European model).

This is a fairly simple protocol (documented here), although synchronization and packet detection works a bittle differently from the other decoders so far:

Screen Shot 2010 04 16 at 00.06.22

Sample output:

Screen Shot 2010 04 16 at 00.05.35

Easy!

  1. Wow really cool… Do you have an OOK decoder planned for 315Mhz(the x10 frequency in North America), this frequency is used for a number of different alarm systems in US, such as Ademco(known as ADI now) etc and now your posts on the visonic sensors has me wondering if ademco and others using OOK also?

    Just how long has OOK been around anyway?

     gwen
    

    • oops ook been around for quite a whie.. On Off Keying..sheesh.. feel slow tonite. On other front I wish you had left comment open on the subject of encryption/security, then you would have seen my comment that if simply securing a link is desired.. then encryption is one slightly fragile way to do that. But a cryptographically secure hash of your command string/readings and a rolling code for an authentication nonce would go a LOT farther on such lightweight CPUs like the ATMega line. All but the shortest keylengths for AES stretch into minutes of processing.

        gwen
      

  2. These decoders should work as is with other frequencies, as long as the pulse patterns & lengths are the same. So all you need is a different receiver.

    Thanks for your comment on encryption/security. Maybe at some point you could help me understand how to do this properly? Perhaps we could discuss this on the forums some day …

  3. Hi JC,

    Back in november you posted about the ELV cost control:

    http://news.jeelabs.org/2009/11/14/energy-tracking-with-cost-control/

    Conrad has the same device I think, but then named Voltcraft RT-110.

    Did you try if you can pick up OOK signals with the OOK scopr from these devices ?

    • Yes – but, I’ve not been able to pick up those signals. I suspect that they are not OOK encoded but some FSK type of transmission. Probably uni-directional, though – the sensors send out every 5s, and the receiver/display listens for 6s to collect all packets when requested.

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