A New Digital Mode For Radio Amateurs

There used to be a time when amateur radio was a fairly static pursuit. There was a lot of fascination to be had with building radios, but what you did with them remained constant year on year. Morse code was sent by hand with a key, voice was on FM or SSB with a few old-timers using AM, and you’d hear the warbling tones of RTTY traffic generated by mechanical teletypes.

By contrast the radio amateur of today lives in a fast-paced world of ever-evolving digital modes, in which much of the excitement comes in pushing the boundaries of what is possible when a radio is connected to a computer. A new contender in one part of the hobby has come our way from [Guillaume, F4HDK], in the form of his NPR, or New Packet Radio mode.

NPR is intended to bring high bandwidth IP networking to radio amateurs in the 70 cm band, and it does this rather cleverly with a modem that contains a single-chip FSK transceiver intended for use in licence-free ISM band applications. There is an Ethernet module and an Mbed microcontroller board on a custom PCB, which when assembled produces a few hundred milliwatts of RF that can be fed to an off-the-shelf DMR power amplifier.

Each network is configured around a master node intended to use an omnidirectional antenna, to which individual nodes connect. Time-division multiplexing is enforced by the master so there should be no collisions, and this coupled with the relatively wide radio bandwidth of the ISM transceiver gives the system a high usable data bandwidth.

Whether or not the mode is taken up and becomes a success depends upon the will of individual radio amateurs. But it does hold the interesting feature of relying upon relatively inexpensive parts, so the barrier to entry is lower than it might be otherwise. If you are wondering where you might have seen [F4HDK] before, we’ve previously brought you his FPGA computer.

64 thoughts on “A New Digital Mode For Radio Amateurs

      1. I won’t be drawn into commenting about Brian’s writing, but after apologising for the dupe there is one thing that strikes me after reading both, how a writer without an amateur radio licence approaches it completely differently from one who has one. I’m not sure how many Hackaday readers have callsigns, but I wonder whether I managed to talk to both those with and those without.

    1. Oh, I’m famous! 2 blog articles for my project. ;-)
      I have to admit that this last article from Jenny is better that the 1st one (sorry Brian), and it is more relevant for the amateur radio community.

      1. How does IP and an almost totally encrypted internet mesh with FCC 97.113 a) 4) on prohibiting intentionally obscured communication? I’d love to be able to check my e-mail on the go.

  1. Hello,

    Sorry to tell you this, but this is not new. At all. My dad had a “modem” called Kamterm that was manufactured by the company Kam if I’m not mistaken, that allowed us to chat over the radio in a digital way using the computer. This was back in 1989.

    We even read the news that were gonna get printed the next day in the New York Times as they used the exact same technology to get the feeds from their international offices every night.

    Heh, we even had what after a couple of years became known as an e-mail.

    As a matter of fact, he was the first person to transmit a wireline job in real time to the customer’s office using that technology without using satellites (which were scarse and way too costly) . It was while working in Halliburton and then became what is called RTO (Real Time Operations) now days and every service company has it.

    And please don’t make another article about answering your home phone remotely using a VHF handy. Also had that. Even before the Kam.


    1. Kamterm was the terminal program that he used for his Kamtronics packet modem. I had a PK12. But that was only 1200 baud. Back in those days 9600 baud was about the fastest you could do unless you got some of the super expensive and rare 56k equipment.

      If you read the news using the equipment then it was probably a multimode TNC that included RTTY and he probably received it over HF. I can’t imagine they used packet to send that.

      This equipment runs at 500k on the 440mhz band. That’s pretty new. Although I think DATV equipment is probably even higher bitrate but that’s not built for the same kind of digital communication that this one is.

    2. Actually all that was history. The device of which you speak was made by Kantronics and there were several before it. And WAY before that was Devices built by Tuson Amateur Packet Radio Club known as TAPR devices. (BTW they are still around last count I had.) And still before those kits were groups like GRAPES Georgia Radio Amateur Packet Enthusiasts Society many like myself were students or past students of Georgia Tech. We had chapters all over the state, and associated groups in other states. We built, provided documentation, and distribution of the WA4DSY’s 56K Baud high speed RF Modems. Dale Heatherington (WA4DSY) for those who don’t know he along with Dennis Hayes designed and manufactured the Famous “Hayes” Modems. Folks like those comprised our organization. This exact system predates the commercial device usage that you mentioned. In fact the first documented business usage was by C&G Electronics to access customer info and billing in the 1980s the first informational usage was by the Dalton Regional Library System for access to materials and client database. These systems were implemented by an engineer who was at the time involved with the creation and support of bulletin boards and what is now called DARPAnet which is (Was) used by the military and higher schools of learning such as Ga Tech, Cal Tech Berkeley, and MIT. This a my friends was the Grandmother and Grandfather of the Internet! NOT Algore!
      WB4IVG Laurin

    3. Oh please! That modem was AFSK. That technology is up there with Apache Indian smoke signals. Sadly, this technology is too sophisticated for Part 97. So AFSK is still supreme.

  2. I really appreciate the low level detail in the “NPR protocol Specification (EN)” document, it is fascinating. At least to me anyhow.

    I think that I spotted a typo on page 5 (3.1 Coding) in “coding for 2 levels GMSK”, I suspect that bottom line with “| +75kHz | -125kHz |” should be “| +75kHz | +125kHz |”. If it is not a typo, then configuration 14 must be as confusing as hell :)

    1. It is a very good spec and it is the very important keyway to have more boards adopt this open protocol for more DIY developements. I also want to review this spec with F4HDK, but I have not yet found the time to do so.

  3. As Ameature operators we must have a device, a radio, a antenna and avoid all costs of internet that is main problem . Like many have utilized solar cells we must now form something new eliminating paying for inter net a Outer-net . I believe this is the technology that helps ameatures traffic and exchange info within the Ameature World. NPR is a good thing!

  4. I think that is awesome that you are experimenting with new digital modes on the Amateur Radio bands – That’s what Ham Radio is all about! (trying new things and pushing the limits of technology!) well done! :)

  5. “There used to be a time when amateur radio was a fairly static pursuit.”. Maybe I’ve been doing it wrong – I thought the idea was to pursue the _signal_, not the _static_ … ;-)

  6. “There used to be a time when amateur radio was a fairly static pursuit.” Maybe I’ve been doing it wrong – I thought the idea was to pursue the _signal_, not the _static_ … ;-)

  7. Many people are attracted more to WhatsApp, Telegram and others compared to amateur radio which have many limitations. We need something great. Especially in internet Era

      1. And your idea is what? Hope to hang onto playing around with 2-way handhelds from the 80s and HF comms that amount “hi, joe” “hi bob” but takes 20 minutes (but hey, you can write down in your notepad your signal strength you had when bob said “hi”).

        Sorry but if we don’t push for newer, more advanced and relevant ways to communicate in amateur radio than the number of people who care about it will decline as the old pool dies off. And then the rest of the world will gobble up any relevant and useful spectrum and you(we) will be left with whatever they don’t consider commercially useful.

        People constantly talk about how much amateur radio did for the communications field, and its true. It did those things, 50-70-100 years ago. Almost all of the modern experimentation in RF has happened in the ISM realm of unlicensed spectrum.

        I’m a general class ham and I often strongly disagree with ARRL and their death grip on some spectrum. I happily support more spectrum going unlicensed even if some is removed from the amateur radio community. Maybe I would think differently if the “no encryption” thing was at the very least modified. But right now its hard to even experiment in these areas because you have a subset of amateurs who it seems are obsessed with killing anything new that might even remotely look like encryption over “their” frequencies. I remember seeing the constant nashing of teeth over DMR.

        1. When all else fails, there is ham radio. We are a million strong spread around the globe supporting our own equipment independent of other communications infrastructure. When commercial communications infrastructure fails, the well trained and experienced ham radio operator is there to aid in emergencies and in communications for rebuilding. Until we as humans can control the weather, the geology and global conflict we will need ham radio operators.

    1. USB and large (for a radio) screens are a thing. Dunno what you’d do with wifi, but IC-9700 has ethernet and can do 128k data on 23cm in DD mode.

      I think some of the newer rigs have VGA or HDMI ports for external screens and the more butique SDR radios have large screens and can use external screens.
      The Flex remote head I saw recently had a large crisp display.

      Some newer radios have bluetooth, but it’s quite rare.

      1. My wishlist items include USB for charging, programming and rig control options and possibly even a soundcard interface for software modem modes. Bluetooth for similar things and a bluetooth headset support. Wifi would be great for remote operation as well. I want to put a radio somewhere and either add it to my network or make it advertise its own AP and then let me operate anywhere in my house or let me vpn in to access it remotely (no cloud services ever).
        I’d even settle for a radio that doesn’t have any of that built in, but makes room and provides connections for something like a Raspberry Pi Zero-w, or Compute Module 3. Maybe then I could have it do codec 2 as well. If there’s a PI then maybe it could include something like a RTL-SDR chipset in it so I can receive using that too.

        1. There are rigs with Bluetooth options, e.g. FTM-400. There are also those with USB sound and serial built-in, e.g. IC-7100, FT-991. USB charging of HTs is lacking, I agree.

          However, the complexity and cost of engineering an IP interface for what is already provided by serial control? Not sure there’s enough of a market to justify that. People remote control their rigs over serial all the time. You can glue an RPi together with a simple serial over IP (think socat, there are tutorials) and do that from anywhere.

          1. What cost? You can make an ip interface for a lightbulb now, so there isn’t exactly a lot of cost involved. The icom 7300 i own supports it (though it wants a PC as a “server” connected via USB). The more expensive icoms support it directly over RJ45 connection. Honestly, i won’t be surprised to see more full on software controlled radio boxes in the future. A knob, a touchscreen and a few ports on the back (usb, rj45, etc) and it be controlled from a PC or Tablet. Seperate the radio bits from the control/brain bits with a fully modular SDR setup.

            Of course that type of design will break the FCCs legal brain because an SDR makes it so easy to access frequencies your not supposed to access and manufacturers are supposed to slice out access to those. I believe they can be sold as test equipment or something though so i guess we will see what happens (and im talking lower priced equipment. Some of the very exensive SDR radios already limit TX on verboten bands, but they also cost a fortune).

      1. Maybe the bulk of you old farts. Thankfully you’re all dying out so we don’t have to listen to you talk about the good old days before no-code hams. Leave it to an old fashioned fogey like you to bring up politics. smh… Just a few more years and we’ll be able to tune in without hearing the likes of you ramble on. I can’t wait!

        1. If you don’t want to listen to us “old farts” then you can either turn your radio off, or spin the dial.
          Maybe us “old farts” are tired of hearing about you young people and your complaining and bellyaching.
          I’ve said it before, and I’ll say it again, common sense, decency, respect, grace, and humility are leaving this world.
          You will be old someday Jay, and then you will be an “old fart” as well. Now, get off my lawn you rotten kids! :)

        2. Sure. And you can log onto your automated search and qsl logging software if you want and pretend you’re a ham by hitting a computer key to have your computer Qsl with another computer keyboard ham while us old foggies actually talk and interact up front and live with another ham. Having a call sign doesn’t automatically make you a ham. …_ .-

    1. Thankfully F4HDK is in France where the archaic 56k limit does not apply. :)
      But I do wish more of the ISM chipsets would do 1270MHz, lots of nice quiet space there for wide band data experiments!

      1. If you want to test NPR solution in the US, you can
        * Either use 900MHz ISM modules (RF4463F30), but you will have to find an amplifier with fast T/R timing commutation
        * Or negotiate with your radio regulator (FCC?) to experiment such protocol, or even change the law

        1. That would require ARRL to lobby for something relevant to radio hams under the age of 60.

          I don’t see that as likely. So instead I make sure to comment on any FCC proposals to create more ISM space and frequencies, even at the expense of amateur bands.

          The closest thing to exciting ive seen come from amateur radio the past few years is the Phase4B stuff, which is really exciting. Sadly we lost our geosynchronous ride into space. A tiny little Islamic country managed to pull it off though. so much for a country that pioneered radio “back in the day”.

          Ill just keep tweeting at musk to give the payload a free lift up on one of his new rockets, maybe someday he will notice the tweets lol.

          1. I’m glad you brought up faradayrf because it sadly proves my point. It was based around using ISM hardware (because, again, all the development is in the ISM space), it was hamstrung by the silly regulations surrounding “encryption”, and it died the second the creators moved on to something else. I mentioned it at ham meetings at two different groups in the city and their eyes just glazed over.

            Https and other movements in the development of the internet and wireless protocols make the requirement that all data be “open air” mostly impossible for anything actually useful. Which is unfortunate. And its why you see all the excitement around 900mhz, 868mhz(outside region 2), 2.4, 5.8, soon 6ghz, etc etc. All those ISM bands. Id love to see the data restrictions on the MURS and FRS bands change to allow more varied and modern uses.

            The FCC also bans anything even remotely spread spectrum below 220mhz but you only have to look at the military to see what modern technology and HF can accomplish if used together. Vastly better TX/RX quality and range.

            As for EMCOMM, i hear that tossed around a lot and there is some truth to it. But if we look at the vast majority of modern disasters we are seeing emergency cell service back in operation in hours to a day or less, and general coverage back up in as little as a few days. And cell coverage offers so many advantages over ham radio at this point most groups quickly and gladly switch back as soon as humanly possible. Immediate text message capability, voip, easy image and document transfers, access to the general internet (a mostly impossible “no no” now because, again, encryption).

            How useful is emergency communications that can’t interface with the outside world? Isn’t that the general point behind behind communications in general? Going to the local ham manning a HF rig and getting him to deliver a “the family is still alive” message to another ham who then calls the family is heart warming and all but not exactly efficent.

            The most exciting thing ive seen in the ham realm is the geosynchronous ham satellite like Qatar sent up. Lots of bandwidth, it doesn’t move, and you could have a ground station thats portable. Too bad the US version (Phase4B) seems to be dead in the water at the moment.

        2. I don’t disagree, but there are a lot of articles being pushed at US hams with links back to your article. I don’t want to see people get in trouble, or cause interference. Not too long ago, there was hotspot impinging on the ISS dedicated frequency. Folks tend to forget that there are rules and regulations. A friendly notification would be nice.
          There are a LOT of things that we could do, in HF, VHF and above. but rules are here to keep us from impinging on others. Also, while I didn’t have the time to investigate the bandwidth, 500 kbps is going to be a pretty wide signal, capable of wiping out an entire repeater band if on the wrong frequency.

          1. 270-750khz of bandwidth depending on signal rate. Its in the quickstart guide in the link.

            You know how many 70cm repeaters are within range of my home (I live on a hill with significant prominence btw)? 1. With a better antenna I *might* be able to hear 2 or even 3 of them, but id be unlikely to consistently reach them. And the only reason that those 70cm repeaters even exist at all is the sudden recent surge in interest due to DMR and the fact that (until recently) the only hardware cheaply available was 70cm hardware. If DMR hardware had started off dual band or 2m only there likely wouldn’t be any 70cm repeaters at all. 900mhz stuff might as well not exist at all, at least to hams.

            We *need* stuff like this to make ham radio relevant again. I was super excited when i got my general license and got a icom 7300, a dual band kenwood mobile for satellite work, a dstar and dmr handheld and built a dmr hotspot. I haven’t touched most of it for a year now and have instead been playing with mostly ISM gear. Why? Because it’s actually relevant. Its not hamstrung by silly archaic regulations (like the symbol rate limit on 70cm that makes this project verboten in the USA, ham or no ham license). Even ARRL has petitioned to remove the symbol rate limits. Unlicensed bands are about to get another big chunk in the 6ghz range. And meanwhile here in ham-land we are saddled with restrictions based on baud rates (and not even bandwidth) and we have people worried about even minor changes in the regulations or afraid of new projects and data modes because it *might* interfere with one of the handful of massively under utilized voice repeaters sprinkled across the country. But I thought the license process itself was supposed to limit interference? If a ham makes a project and sets it up and it interferes then its his fault and the rest of the community is supposed to police itself and correct the issue. Those bands are there *for* experimentation right? Occasional bouts of interference go right along with that and should be part of the process. Then we help each other track down the problem and work together to fix it. Or we could aggressively protect our current 50+ year old tech and crush anyone who accidentally messes up our hobby of collecting callsigns from every county in the country with our 15,000$ off the shelf radio and the 10,000$ antenna tower in the backyard.

            Rant mode off: Interestingly 219-220mhz can have a bandwidth of 100khz for a digital signal. Of course finding a cheap commercial transceiver for sending data over that band might be more difficult.

      2. All modules do any band if you use a transverter, it’s only a “detail”.

        Remember, we are hams, we are allowed to build and test things…

        433 MHz is merely a ham band, it is also a very convenient Intermediate Frequency for ANY higher band.

    2. Any legal thing with a purpose was illegal before.

      OK, it may be. but if you bother no one, cant you do that just for tests?

      Maybe, when the ARRL and FCC will see users, interests, innovation and experimentation, they will start to think twice?

      But lets be realistic: 1200 bps, in 2019, is not enough. We, as hams, and experimentors, are a leading force to change annoying legislation in this domain.

      Lets do it. Hamradio is not just ragchew, it’s also innovation and pushing the frontiers.

      1. The good thing about patents is they expire, and they do so in reasonable amounts of time (unlike copyrights). This particular patent expires in 2022 I think, at which time it will essentially become public domain. Software should work in the same way. Being able to copyright software for over a century is just moronic.

  8. FYI – The source code file doesn’t work. For example it is missing the netsocket directory. Also you don’t need the BUILD directory, as it is created by the Makefile.

    1. Hello Etienne, I discover your comment quite late, sorry.
      There is no “netsocket” directory, and no need for it.
      Currently, I have some troubles building the firmware with “makefile” and GCC-ARM, but it works fine with “MBED offline compiler” / API.

    1. This is not a reason to avoid experimentation of new things :)

      What do they use for basis of their network?
      1200 bps packet?
      proprietary wifi acces points?

      None of this option was satisfactory for us.

  9. @F4HDY under FCC rules, we are either limited to 100kHz bandwidth in 70cm, or the ATV rule applies and we’re not. Do you concur that 4GMSK configuration 22 bandwidth fits within 100kHz?

    Also, as an experimental mode, I think it might be wise to identify my station periodically with a well-known mode, such as RTTY or CW. Do you think this is possible with the hardware configuration you have outlined?

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