Web Pages (and More) Via Shortwave

If you are a ham radio operator, the idea of sending pictures and data over voice channels is nothing new. Hams have lots of techniques for doing that and — not so long ago — even most data transmissions were over phone lines. However, now everyone can get in on the game thanks to the cheap availability of software-defined radio. Several commercial shortwave broadcasters are sending encoded data including images and even entire web pages. You can find out more at the Swradiogram website. You can also find step-by-step instructions.

WINB in Pennsylvania and WRMI Florida both have shows that include interspersed data. To play along, you’ll need a decoder like Fldigi or TIVAR. If you don’t have sufficient radio gear, you can probably borrow some from the Internet.

On the face of it, this might seem to be just a geeky hobby, but we can’t help but think that in places where data is censored, radio might be a viable way to send information. Some forward error correction codes and perhaps encryption could be a way to have a data lifeline to those forbidden from free access to the Internet. After all, history is full of stories of secret radio receivers tuned to the BBC or some other radio outlet, or examples of secret messages in broadcasts, such as Radio Swan. If you know Morse code, you might even get a warning about your impending rescue.

30 thoughts on “Web Pages (and More) Via Shortwave

    1. I believe the reason is different. Hobbyists get access to the spectrum in exchange for remaining hobbyists. With encryption availabla some may try becoming “proffesionals” and providing services without paying license fees. It would be cheating. Ban on encryption prevents the tragedy of the commons.

    2. Ham radio is not a utility, it’s an end in itself. A technical playground, and too often recently just about talking. So you can build up a repeater or packet system, but there is a limit on what you can do with it.

      From comments here, people thinking there should be encryption want it for some other purpose.

      1. I’m thinking specifically of the packet radio modes. Most websites these days use SSL, which means you can’t load them over amateur. The other big problem is that SSH is encrypted, and hits the same regulations. So you can’t even use ssh over packet radio to control your repeater or base station.

        1. Where are your webpages coming from? Some sort of interface, so surely the interface can deal with the encryption.

          But you’re running into other rules. Lots of advertising on webpages, ham radio is not for commercial purposes. How do you get the contents without the ads? I don’t know if the rules have changed, but transfer of many webpages even without ads may be problematic. Rules about third party and maybe profanity.

          The hobby isn’t a utility, to do tasks that should be done elsewhere except for cost or too much work to get a license.

          As for remote operation, there are rules about that, likely changed from when I was a kid. But they exist to prevent unauthorized transmission, so “needing” encryption for control purposes is because you want some other method.

          1. I’m speaking only of US rules as I know very little about the rules elsewhere.

            Ads aren’t necessarily banned. Anything that is a pecuniary interest to the amateur or the amateur’s employer is banned. The FCC doesn’t want you using the free and limited Amateur bandwidth to conduct your business. A ham browsing a webpage via amateur radio which happens to have an advertisement would not necessarily violate the letter of any rule that I am aware of. But a lot of hams who receive it would probably think it was a violation and jump all over it. Somehow people have conflated the rules regarding one’s own pecuniary intrest with a blanket ban on all things even touching anything commercial.

            Back in the pre-cellphone days when some repeaters had autopatches I’ve read that it was even allowed that people could make minor purchases not related to their jobs such as ordering a pizza from their cars on the way home from work. I’m not sure that was formalized in any written rule but I remember reading that this was what was decided by the FCC.

            I’m pretty sure I have also read somewhere that they have ruled that a ham selling things over the radio, so long as it is incidental and related to ham radio is ok. So, for example you can mention that you are interested in getting a new radio and selling your current one, as would be a natural thing to come up in a conversation between hams. If someone happens to have the radio you are looking for or is interested in your old one it is ok to make the deal.

            Yet I’ve heard hams sign off immediately when a conversation started heading that direction because they were afraid their license was about to be revoked just for thinking about money!

            Starting a business buying and flipping radios on the air of course would be an entirely different matter and not at all ok.

            I imagine the rulemakers’ motivation was probably that they just didn’t want businesses using up all the bandwidth as a free service. Imagine if the taxi and delivery companies stopped licensing radio channels or subscribing to cellular service because they can use amateur frequencies for free. They would be out those licensing fees and we would be out of bandwidth for actual amateur purposes.

            The same thing could happen with internet access if all the hams decided to ditch their cellphone bills and do all their surfing via ham radio but that doesn’t seem to be happening. If it did start to go that way then of course I would expect the rules and/or how they are interpreted to tighten.

            Someone out of range of their cellular service, perhaps camping or boating or something like that pulling up a weather page, or maybe some technical info (they are playing on a radio) or even checking their personal mail should not be a problem. (If they can do it without codes and cypher’s obscuring the meaning of the content). By personal email I am thinking maybe looking for a mesage that there is an emergency, or maybe just a message from the non-ham spouse that dinner is ready. Not sitting there trading cat videos all day and certainly not running a business.

            Though, unless they have someone on the other end manually helping them I think it might have to be on 2-meters or above since that is where Auxiliary Stations are allowed. It would be strange to be within range of home via VHF yet not have cellular service. I know there are things like WinLink and APRS on HF though so I don’t quite understand how they operate.

            Then there’s encryption.

            I am sure I remember reading in the rules that “Codes or Cyphers meant to obscure the meaning of the message” were all that were prohibited. I could not find that the last time I checked though. Perhaps the rules have changed and now it really is just encryption in general that is banned? If that is still the current rule, that it’s only when it obscures the meaning that it is prohibited then I would think that one could come up with a scheme to use public key encryption to verify one’s identity but still allow anyone receiving to decode the message.

            I imagine one would take a control code, concatenate a sequence number or a timestamp to it. Encrypt that with a private key. Then concatenate the public key and transmit that. Anyone who wants to read your message could then use the attached public key to decode the encrypted part. The meaning is not obscured. But nobody can fake your control code because they don’t have the private key which is necessary to encode it. Re-sending an old, already encoded message would not work because the sequence number or timestamp would be old.

            That would be great for securing the controls of a repeater or other auxiliary station or checking that personal email I mentioned earlier. I think most repeaters just rely on “well, nobody has ever tried to hack it” as their only security. It seems to work. But can you imagine setting up a server on the internet and “securing” it that way?

            “As for remote operation, there are rules about that, likely changed from when I was a kid. But they exist to prevent unauthorized transmission, so “needing” encryption for control purposes is because you want some other method.”

            See Repeaters and Auxiliary Stations.

            I am not a lawyer, this is just my understanding from what I have read. No legal vice is implied here. Read the rules yourself.

            I do think that for ham radio to remain relevant among current and coming generations It’s going to be necessary to find the right balance in these rules, their interpretation and enforcement. Too strict and young makers will just stick to cellular services. Too loose and a handful of people using the ham bands as their personal network could use up the bandwidth for everyone.

    3. Surely the solution is “simple”, ensure anything encrypted is in a short burst transmission, this sort of thing won’t step on other bandwidth users, probably won’t be noticed at all, and if anyone does decide it illegal the source will be hard to locate. The trouble ofcourse is getting as much encrypted data as someone wants to send transmitted sufficiently fast not to mess with anyone else’s signals, plenty of irritating physical limits on data per second for a given carrier freq.

  1. I should point out given a recent comment that hams do not send data over “voice channels”, at least not on the shortwave bands. Teletype, SSTV, packet, and fax (is that still being done?) are not sending audio tones. These are FSK signals, putting pure audio tones into an SSB transmitter results in the same output signal that shifting an RF oscillator presents. It’s just mkre convenient to do it by feeding audio signals.

    But broadcasting has always been seen as a way to reach people. That’s why a lot of countries had significant SW stations at one point, to present themselves directly to people in other countries. That’s why there was jamming, and sometimes restrictions on shortwave receivers.

    Even ham radio has been seen as a tool for propaganda. In the USSR, the hobby was cintrolled enough that there was speculation that the hams were supposed to hype the country. And certainly other countries thought just having hams talk to Soviet hams was a good propaganda tool (just by talking about their average home life).

    Sending digital data is bound to be suspect. And how much can one station send? It makes sense, fading issues aside, to add some data to complement what’s being spoken, but voice is still pretty simple to send and receive.

    Satellites are the way for clandestine communucation. No need for big antennas, and a lot of people have dishes for tv. Harder to jam, and if an uplink is needed, more secretive than shortwave. High bandwidth, in 1994, a local BBS got its Usenet feed via satellite, the relative few messages going out could go via phone.

  2. Wooo! Made it onto hackaday! The example images were broadcast via WRMI on last Wednesday’s “This Is A Music Show” program, decoded by @Plano26 in Arizona. You can hear the show and try to decode images yourself from show recordings at thisisamusicshow.com

  3. Encryption, is for people wanting to hide something. Only those with the key, get to listen/see the secret. Everyone else receives garbage. Only a limited number of channels, allowing privacy, will encourage more people, usually undesirable, using the channels, for garbage, no one else can use. Usually, encryption keys, carry a price, and someone paying for the privilege, while others are locked out. It’s no longer public, or free.

  4. I don’t understand how most encryption actually works, but if you are going to make the argument that the ban on encryption is hindering progress and development of new technology by experimenters on the ham bands, then publish your encryption key publically. That way you can still experiment all you want with new modes, it uses your same developing technology, but is not un-readable by anyone with access to the key or whatever. Even in that case, though, I don’t see why you would need to try this over the air at all, but whatever.

    I mean, Morse Code sounds like a bunch of garbage until you apply the very publically available decoding algorithm.

  5. Fascinating. Reminds me a bit of my early days when I listened to DRM radio with an EF95 based direct conversation receiver and DREAM running on a laptop with soundcard and Windows XP SP2..
    The receiver used a 4MHz crysta (+cap) to receive RTL Radio on 3995 KCs.
    DREAM was cool, because it could work with a 7KHz signal already. Other software needed at least 12KHz.
    The software also had a built-in browser that showed pictures and text, just like a real www browser would. This was sooo cool! 😎

  6. Well, if you think about it, Morse is a form of encryption as are SSTV, Packet, etc.
    The only difference is the decoding method is public knowledge.
    Messages meant to be encrypted with a private key don’t belong on the ham bands, with
    the exception of remote control of hardware. It is my understanding that the Evergreen
    Intertie in Washington State abandoned their radio links in favor of going over the net.
    Just my own opinion, but I would have stayed with the radio links. Less dependence on
    commercial infrastructure that way. Keeping repeater control codes private is necessary as
    you don’t want every ham knowing what sequence of tones are needed to shut your repeater
    down. I see no need for encryption on the ham bands but higher baud rates would be nice.
    For instance, with SSTV, if the speed could be increased without increasing the bandwidth
    you would have shorter transmission times thus freeing the band up for more users.
    One thing I’ve been interested in is EHSMC, extreme high speed morse code.
    To the ear, it sounds like a quick buzz, and is not meant to be decoded by the brain.
    EHSMC is meant to be sent by machine over standard ham frequencies, received by another
    machine and decoded. It could still be slowed down for the brain to decode however.
    Besides, a quick blip is a lot harder to pin down and trace than someone sending morse
    at 13 wpm. So, my question is, what is to keep someone with ham equipment from sending a
    quick 1/4 second or faster digital signal that is encrypted? Since encryption is illegal
    on the ham bands, the person wanting to do so probably wouldn’t advertise their call if they
    had one. There are plenty of spy number stations out there along with other clandestine
    radio stations. Encryption on the ham bands? No thank you.

    1. There is encoding and there is encryption. Encoding is simply a form of modulation or a series of publicly known symbols on a medium that are intended to convey information. Encryption is intended to obscure the message.

      To use a concrete example: Morse Code was intended to be decoded. Elliptical Curve Encryption is intended to obscure the message to anyone who does not have the key.

      All that said, I agree with you and everyone above, encryption has no place in amateur radio. However digital signatures may be okay, depending upon the application. So sending a reception report with a digital signature that could only have come from a particular person is probably okay.

      1. There was a time about 1973 where the US FCC brought up the concept of automatic ID for transmitters. I can’t remember how serious it was, so maybe some of what I remember was conjecture. So high speed morse sending an ID every time the transmitter stopped sending. It was built into the transmitter. And how was that going to work in ham radio? But that would solve the “ID problem”.

        Except, except for bootleggers, people use their callsign, it’s the rule. So it can be trusted. It’s not some handle picked out by the individual. And given what can be conveyed, how often does one need to be certain of the sender? Ham radio is not the internet.

    2. Speaking of analogue SSTV.. It’s possible to transmit very fast. Robot 36, Robot 8 as frame-sequential transmission (R/G/B) or monochrome in 7s/8s.
      Before the advent of computer-based SSTV, SSTV was also transmitted in 4s or 2s, even. But it wasn’t pretty.
      Thing is, quality will usually degrade if transmission speed is increased. You’ll loose resolution, so to say. So another approach is needed. Like, transmiting in gray scale only and let an AI algorithm find out the colours after the picture was received. The simplest method would be to translate the hues to their matching colour pendants, I guess.

    1. I love generalized comments like this with no basis for fact within them at all. You wonder if the commenter has any idea what he or she might be talking about. As for the ‘ham bands’ being unused – tune around on any given day or night, and you will find SOMEONE out there, either sending CW, talking, or using digital modes. As for them being boring – well, it’s like anything. You get out of it what you put into it.

      1. There have always been people who think ham radio should be something else, ie what they want. From some of the comments here whenever the topic comes up, I suspect some don’t really know much about the hobby, and without that understanding, they want to invoke all kinds of stuff.

        Some see or present the hobby as “elite”, a desire to keep others out. But the code testing had a reason (and by international agreement, mandatory), and the testing the gateway to relatively unrestrictive rules.

        The code testing gone, the testing really very simplified for entry level, but aplarently that’s not good enough.

  7. I have changed my view on the amateur radio encryption clause over the years. I used to be opposed to it, but lately I’ve come to understand why it’s there.

    The whole purpose of the encryption clause is to prevent people from transmitting things whose information is *deliberately* concealed. The reason why this is done is because there are very few non-nefarious use cases for encryption in amateur radio. A good example of this is all the rioters at the Capitol buying up BaoFengs because they thought they couldn’t be tracked. There’s still plenty of ways to achieve the non-nefarious benefits of encryption.

    For example: In response to an above comment, a method I use for authenticating messages/commands is the following:
    The computing devices at all ends have a hidden key and a hidden (time based – minute resolution) hash function whose input is the key, the time, and the message I am sending, and whose output is an eight character alphanumeric code.
    Any message I send is put through the hash function, and then the output of that function is appended to the end of the message/command.
    On the receiving end, the last six characters are stripped off, the message is put through the same hash function multiple times (with the time varying +/- up to a few minutes) and the outputs of that function are compared to the received hash output.
    If any of them match, the message/command is considered authenticated.
    This does not violate the encryption rule because the meaning of the message is not obfuscated.

    In my experience, anyone who talks about the rules for amateur radio being overly strict is someone who either: (a) does not frequently operate on the air. (b) has heard this criticism in the past and took it at face value. (formerly guilty) (c) wants to do something on air that they don’t want other people to know about.

    The rules are very loosely enforced. In general, you have to be deliberately violating the rules before you will even hear anything.

  8. I tend to agree with excluding encryption but do not include digital signatures in that definition. Public keys allow anyone to verify that the signature is indeed that. Do I think everyone at FCC, etc. only cares about pressure from big corporations? No, but the amateur services will be compromised or curtailed if the big telecoms think its hurting their profits. So it must be kept free of commerce of any significant value so they can be “told it’s none of their business”. More and more, this also applies to competing with commercial satellite businesses.

    Also this: if you think there isn’t a fair amount of steganography already being used on amateur bands, please remove head from sand.

  9. The equipment for the shortwave is quite expensive.A SSB transceiver costs several thousand USD. If you make an SSB transceiver from scratch, there are several critical parts: a linear power amplifier and a low noise RF amp. The best and cheapest path to do this – the weaver transceiver. There isn`t any IF tract with a bandpass IF filter. One disadvantage of this – you need a RF geterodyne with a frequency of 4 times more that a working transceiver frequency. But in my own opinion – a digital modulation/demodulation the best solution for shortwave transmitting.

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