Licence-Exempt Network Has High Ambitions

It’s safe to say that the Internet of Things is high on the list of buzzwords du jour. It was last seen rapidly ascending towards the Peak of Inflated Expectations on the Gartner Hype Cycle, and it seems that every startup you encounter these days is trying to place an IoT spin on their offering. Behind all the hype though lie some interesting wireless technologies for cheaply making very small microprocessors talk to each other and to the wider world.

Today we’d like to draw your attention to another wireless technology that might be of interest to Hackaday readers working in this area. UKHASnet is a wireless network developed from within the UK high-altitude ballooning community that uses cheap licence-exempt 868MHz radio modules in Europe and 915MHz in the Americas. The modules they are using have a surprisingly usable power output for licence exempt kit at 100mW, so the system has been designed for extensibility and bridging through nodes mounted on balloons, multirotors, or even seaborne buoys.

All UKHASnet packets are sent as human-readable plaintext ASCII, and the system borrows some of the features of amateur radio’s APRS. All packets are considered unreliable, all nodes repeat the packets they receive with their own node ID appended, and there are gateway nodes that make the packets available to the internet. There is a repeat number built into each packet to stop packets continuing ad infinitum.

Building a node is a simple process, requiring only the radio module, a microcontroller, and a battery. As examples they provide an implementation for the Arduino, and one for the LPC810 microcontroller. Their preferred radio module is the HopeRF RFM69HW, however the system will be capable of running on other modules of the same type.

So far the UKHASnet people have proven the system over a 65km range, created nodes on the sea, attached it to quadcopters, and built a host of other nodes.

This network differs from its commercial counterparts in that it has no proprietary IP or licencing from a standards body. And despite the name, you don’t have to be in the UK to use it. All data is in the clear, and thus it is likely that you won’t see it in mass-market commercial products. But it is exactly these features that are likely to make it attractive to the maker community. Your scribe will probably not be the only person who goes away from this article to suggest that their local hackspace finds the space for a UKHASnet node.

This is the first time we’ve featured UKHASnet here at Hackaday. Plenty of projects using licence-free radio modules have made it onto these pages, though, including this extreme-range remote controller for model aircraft, and this weather station sensor network that could have probably found UKHASnet useful had its creator had it to hand.

18 thoughts on “Licence-Exempt Network Has High Ambitions

    1. That’s a lesser concern considering it’s on the license free frequency commonly used by walkie talkies and wireless mics etc. so you’re getting it constantly jammed.

      1. Take a look with an RTL-SDR and see what the occupancy is. In most environments the QRM from other devices isn’t so prevalent or continuous as to preclude anything else using the frequency, after all if it were then none of the other devices would work either. And the HopeRF modules have quite a significant power output at 100mW compared to many other devices.

        So I think it would be inaccurate to say that any device would be constantly jammed. It would however be interesting to hear from a UKHASnet insider as to whether they’ve had any issues with this.

      2. Actually, the particular part of the spectrum used by UKHASNET is limited, in Europe, to 10% duty cycle. Which is to say, devices are not allowed to transmit more than 10% of the time. Therefore, it’s extremely unlikely that a UKHASNET node will find itself in an environment where it sees constant radio interference.

        The devices you mention do not use this band (and they must not, since they need to transmit constantly.

    2. But can’t you use that plaintext packet network to transport soemthing encrypted over it?

      When facebook used xmpp for there messenger a buddy and I used kopete as a facebook messaging client and we managed to use OTR to communicate via the facebook servers.

      Something like that should be possible here, too.

      1. But is it legal to use APRS with encryption? Obviously a packet can contain anything so technically there is no reason why you couldn’t implement another protocol layer with encryption or whatever you need. Either way it is the radio version of messages in a bottle, you throw it out there and see what happens. One way around the potential legal limit on encryption is to add a checksum that is encrypted (signed) so that you can validate the packet contents without having to obscure the contents.

        1. It’s not legal to use *APRS* with encryption, the key letter being the “A”. Our licences forbid it. But though this borrows some of APRS’s ideas it’s not in an amateur band or used under an amateur licence. So encryption is not a problem.

      1. > I dont think you can encrypt packets in the 915 band.

        I think that makes as much sense as what a friend’s physics teacher used to say:

        “downhill is easier than by foot”


        (And yes, perhaps it’s forbidden, I don’t know. But how would anyone verify that?)

        1. the protocol must be known to the FCC, they don’t go into detail on how but they do enforce it and you see this in all amateure bands where one pops up and goes down within a month

  1. These networks have their limits. I was just at an elecetronics expo and I stopped to chat with a company offering the same service.
    Problem is one message can be max 12 bytes, you can only send 144 messages per day and receive 4 per day. That for the price of a 300mb mobile dataplan.
    Not worth it for me.

    1. I think you may have this confused with another type of network. This one uses licence-exempt radio modules rather than the cellular phone network, so you can send as many packets as you like and it won’t cost you a bean. Which I am sure you will agree is something to be happy about.

  2. I’m a little confused with both this write-up and with the linked page at UKHASnet. Is this a proposal for a low-capacity mesh network of sensors, or for a method of point-to-point links?

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