back to article Chirp unveils free tier of shouting-at-IoT devices audio net tech

IoT audio networking tech firm Chirp has punted out a free version of its software development kit. Chirp’s USP is audio-based networking, as opposed to the electromagnetic spectrum we’re all familiar with thanks to Wi-Fi and Bluetooth. Using normal speakers and microphones operating within audible and ultrasound ranges, Chirp …

  1. Anonymous Coward
    Anonymous Coward

    This audio-based network technology sounds revolutionary.

    I suppose they must have some hardware device that MOdulates the data into sound waves and another that DEModulates the sound wave back into data..

    I'm surprised nobody thought of it before. In fact I can think of an extension to this technology. Instead of the devices needing to be close to each other, you could send the sound waves down an ordinary phone line. No need for any fancy ADSL connection.

    1. Chris G Silver badge

      I am pretty sure I have read something about this decades ago for spies sending a burst of sound down a phone line.

      I can't remember if it was fiction or an article but it was a long time ago.

      The agency in the Lensman series used the chirp at the beginning of each Hyperwave transmission to read every message that had ever been sent, so the concept is certainly not new.

      1. PhilipN Silver badge


        Believe it began in WWII?

    2. Charles 9 Silver badge

      Thing was, you needed a phone line of reasonable quality to get practical transfer rates out of wired modems. This has the neat trick of being able to perform modem functions in open air. As noted, it's interesting in situations where neither wiring nor EMI are an option. And yes, TEMPEST does take acoustics into consideration, so don't even try.

      1. Anonymous Coward
        Anonymous Coward

        And yes, TEMPEST does take acoustics into consideration, so don't even try.

        Doesn't matter when the biggest enemy of the state is the MoD itself, and in particular the Quisling wing based near Bristol.

    3. Daniel Jones (Chief Science Officer, Chirp)

      Now you're onto something... I reckon we could hit rates of ooh, maybe 56kbps over a phone line... We'd best get back to the lab, this could be a gamechanger.

      In seriousness, we spend an unhealthy amount of time digging through old Bell/ITU specifications and owe a big debt to our modem forefathers. Our key innovations are in making it work over the air in noisy, reverberant real-world environments, which poses problems that are deceptively tricky.

  2. PhilipN Silver badge


    Gave this a go when a simple prototype was available to shoot small files from one iOS device to another. Blindingly simple in concept. Love it.

    Would, by way of trivial example, Apple please incorporate this into HomeKit so I can be alerted by the teapot when the tea’s brewed, by the saucepan when the egg is soft-boiled and by the toaster when the bread is crisp and brown. Thanks.

    1. Daniel Jones (Chief Science Officer, Chirp)

      Re: Brilliant

      Cheers for the early adoption! Give us a shout if you'd like to play with the modern incarnation - we now embrace Linux, RPi, Python, JS, etc etc, which makes it infinitely more hackable than the iOS app ever was :-)

      ( + if any teapot-makers out there wanted to build a Chirp-based interface, we're here for you with PG Tips at the ready...)

  3. John Smith 19 Gold badge

    "chirp at the beginning of each Hyperwave transmission"

    No, that would be a James Blish novel called (IIRC) The Quincunx of Time.

    There's an old PopSci article about doing a 2bps spread spectrum data stream that can sent over a TV audio channel to activate toys (developed by a toy mfg).

    The big challenge is the noise issues in free space transmission. Industrial environments can be very noisy. High pressure air (used for driving some valves) can screech at the sound barrier.

    So yes a system that can do reasonable data rates surrounded by broad spectrum and high amplitude noise is pretty clever. The question of course is wheather it's more power efficient than just leaving the radio transceiver on?

  4. ab-gam

    Pet Safe?

    I'm curious about the 'infra-sound' spectrum they mention and how it might overlap with the hearing ranges of various creatures - including the odd human who could hear the base oscillator in greenscreen monitors when the computer was off.

    It's not like our pets need another reason to randomly go crazy.

    1. Stoneshop Silver badge

      Re: Pet Safe?

      including the odd human who could hear the base oscillator in greenscreen monitors when the computer was off.

      Not that odd, it's just 15625 Hz, might be even lower depending on the free-running behaviour of the line oscillator. It was common for people to be able to hear audio frequencies that high if they hadn't been attending heavy metal/disco/house[0] concerts regularly.

      [0] depending on decade

    2. Daniel Jones (Chief Science Officer, Chirp)

      Re: Pet Safe?

      I can confirm that it is pet-safe as my cats (and other Chirpers' dogs can attest) - to them, it just sounds like a high-pitched melody. And because there's very little background noise in the near-ultrasonic range, we can play the Chirp signals at a low volume, so it sounds like a _quiet_ melody.

      On the human front: Some of the younger members of the team can pick up Chirp signals sent in the 17kHz range, but we've yet to meet anyone who can hear a 19kHz payload...

      1. John Smith 19 Gold badge

        And because there's very little background noise in the near-ultrasonic range


        I've heard that when TV's had ultrasound remote controls they could be fooled by jingling coins. Presumably the "chink" produced noise that was broadband and loud enough to spoof the (very simple) channel changing protocol used.

        I imagine your system is much more resistant.

  5. GIRZiM

    It's a terrible solution

    To crack it, all you need is a bunch of teens high on drugs!

  6. ianmcca


    "Chirp doesn’t go to great lengths to bake in security on the reasonable grounds that it’s a transport protocol akin to Wi-Fi; it’s up to the user to apply suitable security measures to his connection"

    This just sounds wrong to me.

    1. Daniel Jones (Chief Science Officer, Chirp)

      Re: Security

      It's the same approach to abstraction taken by any sane protocol stack - just as TCP/IP itself doesn't provide any innate security considerations, it's straightforward to apply crypto on the higher levels of the stack (HTTPS being a canonical example).

      We provide sample code for RSA-over-Chirp, TOTP-over-Chirp, and so on, which makes it straightforward for third-party devs to create secure Chirp links using industry-standard encryption.

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