Reverse Engineering an AC Signal Protocol

[Arpad] has spent quite a bit of time reverse-engineering a home automation system, and, as he is quick to point out, presents the information learned for informational purposes only. He’s really done his homework (and documented it well), looking into the US patent application, and figuring out how the protocol works.

If you’re wondering how someone is able to send a signal over an AC sine wave, at least one technique is the proprietary [Universal Powerline Bus]. This works by sending precisely times pulses in conjunction with the wave that would exist normally. Given the correct software on the other end, this can then be decoded and used for whatever data transfer is necessary.

Although as engineers and technologists, we certainly don’t condone stealing patents,  part of point of one is that others are allowed to learn your secrets in exchange for some legal protection. [Arpad]‘s motivation in doing this is that the technology is only widely available in the US with our puny 120 VAC 60Hz power. With this knowledge, he’s been able to transfer it to work with European 230 VAC 50Hz.

Comments

  1. Joshua says:

    I wouldnt call 120v puny comparing to Euro 230v. It might be 230v but the median service amperage is around 90 amps vs 200 in the usa.

    It’s why those damn tiny stoves and ovens in German kitchens suck so bad!

  2. rageahol says:

    what the fuck does “stealing patents” even MEAN? patent protections only apply to commercial uses of a technology. if you’re dicking around with a project at home, patents dont have a goddamn thing to do with it.

    • angus says:

      It’s not true in general that patent infringement has to be commercial. In some jurisdictions, just using or giving away a patented device can be an infringement. This is why e.g open source projects have to avoid infringing patents, even if they’re not selling their product.

  3. Bryan Price says:

    (Patents -eq Secrets)

    False

    • AussieTech says:

      Yep, Patent ain’t Copyright. America invented Patents, but has some very strange interpretations compared to the rest of the world, however Patents are to protect innovators from unlicensed *commercial* exploitation of their ideas, not a blanket prohibition on replication or publication.

      Many Aussie (240V 50Hz) houses built in the 50’s and 60’s had a second phase specifically for the electric stove.

  4. fartface says:

    ” puny 120 VAC 60Hz power”

    yeah, I dare you to latch onto two bare wires with that “puny” 120V.

    If you are going to call anything american puny, please talk about our Girly football players. A proper European Rugby player will kick the arse of any of our fat and padded girls.

  5. DanJ says:

    Nice job. Some real engineering here.

  6. dl7und says:

    Oh friends, what is this? UPB is “proprietary” exactly why? Because you can download the whole protocol specification so you do not need to reverse engineer it?

    http://pulseworx.com/downloads/upb/UPBDescriptionv1.4.pdf

    The main problems with converting any powerline protocol designed for the US grid (X10, Insteon, UPB) to European needs are different timing (60/50Hz frequency), slightly different voltage (not too important for the signal transmission itself, only for circuit operation) and the three European phases versus the one feeding US appliances, so the signal needs to be repeated and bridged.

  7. ejonesss says:

    “we certainly don’t condone stealing patents”

    we cant steal a patent here since the heart of the swith is a pic chip.

    the pic chip is a programmable processor of some sorts.

    well you could re create the switch electrically but without the firmware code your device is useless.

    it may be possible to dump the contents of the pic chip or if you can get the source code you could flash a pic your self or interface your computer to the device.

    also what is the frequency of the pulses?

  8. N0LKK says:

    Not to dismiss the efforts of Arpad, signaling over power conductors is nothing new. Unless you need to control up to 250 items/points, there are simpler ways to go about it, I believe.

  9. Drone says:

    Are EU three phase house installations wye or delta connected? How to safely and simply bridge a signal of around 100KHz across three EU type 220VAC/50Hz phases? I would think something like a simple LC bandpass filter or RC high-pass might work?

  10. Eduardo Buendia says:

    Hello, the 3 Phase Lines in EU are Wye almost everywhere, although there are some Delta on Switzerland. There are some issue to your Idea with bandpass, they work for a few meters but not for long distances.

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