[HN Gopher] Hacking Ham Radio for Texting
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Hacking Ham Radio for Texting
Author : RageoftheRobots
Score : 68 points
Date : 2021-11-17 17:21 UTC (5 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| jrockway wrote:
| I think if this interests you, you'll like the LoRa-based devices
| better. They're unlicensed, so you can encrypt, use it without a
| ham radio license, etc. LoRa is pretty proprietary which is evil
| and all, but the end result is good.
|
| Hackaday has some good example projects:
|
| https://hackaday.com/2020/04/25/a-lora-im-me-for-the-end-of-...
|
| https://hackaday.io/project/171790-armawatch-armachat-long-r...
| livueta wrote:
| Came here to post this; also, https://meshtastic.org/. Still in
| (very) active development, but it genuinely works quite well
| and is very exciting.
|
| Imo lora and similar protocols are a great example of the
| innovation fueled by the existence of the ISM bands.
| spiritplumber wrote:
| https://www.f3.to/cellsol/ This one is geared towards low
| power consumption, for throwies.
| mikece wrote:
| Texting via APRS has been a thing for about 20 years. It's also a
| fantastic way to publish both your phone number and the numbers
| of the people you are texting in an easy to skim format. Digital
| modes is one of the areas where the HN crowd could introduce
| significant advancements to Amateur radio (while pissing off all
| of the older HAMs who just want to talk about the weather on
| 40m).
| MisterTea wrote:
| And before APRS we had packet radio[1]. Around 1992/3 I
| remember going to Boy scout camp at ten mile river and a
| scoutmaster from another troop had a packet radio setup
| connected to a luggable PC in one of the buildings. I dont
| remember what it was for but the idea of wireless digital
| communications was exciting. Now its everywhere.
|
| 1. https://en.wikipedia.org/wiki/Packet_radio
| mikece wrote:
| APRS is built on packet radio (AX.25 protocol IIRC).
| edrxty wrote:
| It's safe only because nobody cares enough about ham radio to
| bother skimming anything.
|
| I've been pushing for encryption for years but just posting
| this well get a bunch of elmers posting upset replies.
|
| It's frustrating constantly being under the thumb of a
| generation that will not yield to progress
| detaro wrote:
| Don't conflate "it's extremely obviously not legal" with
| "people don't like it" (the latter camp you can always
| ignore, they fundamentally can't do that much in most cases
| except not support you. See e.g. the whining about pretty
| much any digital mode ever). But encryption on ham bands
| falls in the first bucket, which is a problem, and I doubt
| that's simply a "we need to advocate for changing it" matter.
|
| Fun fact: in parts of the world, you can transmit pretty much
| whatever you want on CB, nobody is stopping you from running
| encrypted digimodes there. And for slow transmissions, one
| can probably squeeze something through ISM bands, despite the
| limitations there.
|
| And you probably could develop a good mode on ham bands that
| has the foundations and does signatures but not encryption,
| and can switch to encrypted on other bands.
| 83457 wrote:
| How would encryption work?
| jrockway wrote:
| Encrypted communication is not allowed on the ham radio
| bands.
| logfromblammo wrote:
| One could still run a numbers station? There's no way to
| prove the code words have any meaning beyond what is
| obvious.
| hmrr wrote:
| That's a sure way of ending up with several old men
| yielding yagis like swords descend upon your house.
| unoti wrote:
| > One could still run a numbers station? There's no way
| to prove the code words have any meaning beyond what is
| obvious.
|
| I'm not so sure one could, legally. A number station
| would broadcast regularly a one-way communications, with
| no clear meaning. Here's an excerpt of the law from FCC
| part 97, which is actually surprisingly short and
| readable. It prohibits:
|
| "messages encoded for the purpose of obscuring their
| meaning, except as otherwise provided herein; obscene or
| indecent words or language; or false or deceptive
| messages, signals or identification.
|
| (5) Communications, on a regular basis, which could
| reasonably be furnished alternatively through other radio
| services.
|
| (b) An amateur station shall not engage in any form of
| broadcasting, nor may an amateur station transmit one-way
| communications except as specifically provided in these
| rules..."
|
| https://www.ecfr.gov/current/title-47/chapter-I/subchapte
| r-D...
| abfan1127 wrote:
| FCC rules won't allow encryption. I'm not sure why the rules
| were made originally.
| giantrobot wrote:
| Encryption is indistinguishable from noise. So the
| difference between a high power encrypted transmission and
| high power jammer is semantic. Radio transmissions also
| propagate. Sometimes they propagate in unexpected ways
| reaching much farther than expected.
|
| If you combine these things you end up with encrypted
| transmissions raising the noise floor for everyone in a
| band with no way to know if that noise is a transmission or
| actual noise. A lot of ham bands are already very noisy
| from natural sources, a bunch of encrypted transmissions
| increasing the noise floor just serves to make those bands
| inaccessible.
|
| The propagation makes this problem even worse because
| encrypted transmissions can raise the noise floor for hams
| hundreds or even thousands of miles away. Even if an
| encrypted transmission uses a very narrow bandwidth (no
| worse than other digital modes) you're still monopolizing
| part of a very small band with a private conversation
| preventing others from using the shared resource.
|
| To make matters worse encryption necessitates some form of
| error correction. Whether this is forward error correction,
| retransmission, or whatever it's necessary for a receiver
| to receive a correct ciphertext in order to decrypt a
| message. Error correction necessitates a higher duty cycle
| in order to send the error correcting overhead. So
| encrypted transmissions last longer than the equivalent
| unencrypted digital mode tying up limited bandwidth for a
| longer duration.
| trcarney wrote:
| > Encryption is indistinguishable from noise. So the
| difference between a high power encrypted transmission
| and high power jammer is semantic
|
| The difference, from an RF perspective, of an encrypted
| signal and a non encrypted signal is non-existent as the
| encryption takes place before the modulator. Therefore
| encrypted signals won't impact the noise flow for
| everyone in the band. This would only occur if the
| operator were using frequency hopping.
|
| >you're still monopolizing part of a very small band with
| a private conversation preventing others from using the
| shared resource
|
| Depending on the technology used in the receiver, this
| also isn't true. There are numerous techniques to allow
| for multiple carriers on the same band. CDMA for example
| would allow for this. It would take some coordination to
| make sure each carrier is using a different code but
| should be feasible for amateur radio operators. It all
| depends on how sophisticated their receiver is.
|
| >Error correction necessitates a higher duty cycle
|
| This is true and is why encrypted signals have lower data
| rates. So instead of having a longer transmission you
| lower the data rate to get the same effect.
| tjohns wrote:
| Ham radio relies on self-policing within the community to
| ensure compliance with the rules - the biggest one being
| "no commercial use".
|
| The "no commercial use" rule ensures companies aren't using
| the limited ham radio spectrum as a workaround to getting
| their own dedicated license and frequency allocation.
|
| If encryption were allowed, there'd be no way for other
| users to verify whether traffic is commercial or not.
| alibarber wrote:
| I always thought that encryption not being allowed was a
| way to discourage illegal commercial use of it.
|
| No business wants their comms in the clear with no means
| of verifying the sender of the message - so ham radio
| would be useless to them.
| fragmede wrote:
| But even not-for-business, I don't want someone else to
| be able to impersonate others, so signatures/verification
| still needs to be supported. Otherwise someone who's good
| at voice impersonations of others could wreak havok.
| tjohns wrote:
| There is no rule against using digital signatures for
| authentication. Your actual message just has to be in the
| clear.
|
| The exact wording is in 97.113: "No amateur station shall
| transmit... messages encoded for the purpose of obscuring
| their meaning".
| Enginerrrd wrote:
| Because way back when long range radio was a plausible way
| for spies to communicate back to the homeland.
| sseagull wrote:
| I am hoping they explained why.
|
| Most people who complain about the encryption regulation just
| completely disregard the reason for encryption in the first
| place (ie, all other regulations become unenforceable if
| encryption is allowed).
| edrxty wrote:
| The unenforceable argument isn't really a thing. If we look
| at some common encryption standards, the call sign is in
| the clear as it has to be for routing.
|
| In the case where someone is swearing with their friends
| over an encrypted channel, it's just not a problem, no
| child will hear the swears without a quantum supercomputer.
|
| In the case where a business is illegally using ham bands
| to avoid paying license fees, they can already do this,
| nobody is actually checking. You can encrypt P25 on the
| bands all day long because nobody has radios that work with
| that digital mode and nobody will spend the time running
| signal analysis to figure out that A) it's P25, B) it's
| encrypted and C) where it's coming from. If it became
| rampant the FCC has the tools to very quickly figure out
| all of these things and if the broadcasts don't have a call
| sign and are coming from a business premises then it's
| obviously breaking the law anyway.
|
| If it could be a problem, it already would be. All the
| Chinese digital business radios support encryption now.
| We're just not allowed to use it because people are scared
| of bogeymen
| BenjiWiebe wrote:
| Yes, people are checking. Repeated abuse of ham radio (in
| the US anyways) will eventually get enough hams mad that
| they will report to the FCC, which does investigate and
| crack down from time to time.
|
| No, it isn't an instant 100% chance of retribution.
| edrxty wrote:
| People are checking FM because it's trivial. I have yet
| to hear of someone getting caught using digital
| encryption entirely through band monitoring (ie not doing
| something obviously stupid elsewhere like bragging about
| it on social media)
| ajsnigrutin wrote:
| It's 2021... ham operators hear someone using the band
| for something digital, and then use the one of the many
| cheap SDR sticks to check what is using the channel.
|
| One call to a regulator, and it's done.
| jjoonathan wrote:
| Do they? Maybe we need to figure out the essential subset
| of regulations that preserves the most essential aspects of
| the system while still permitting encryption.
|
| I have no doubt it will be a huge mess and take a few tries
| to get right.
|
| We should get started already -- if we don't, HAM will die,
| and it will deserve to die.
| sseagull wrote:
| Mostly. Ham is meant for play, not as a primary means of
| communication or for commercial purposes.
|
| If everything is encrypted, how could you tell? How could
| you even tell that the users were licensed?
| jjoonathan wrote:
| By not encrypting the call signs because unencrypted call
| signs aren't the problematic restriction. It's the
| content restrictions that are stifling in the modern
| world.
|
| Also: progress has changed the landscape. HFDF used to be
| difficult for the military but now it's easy for
| hobbyists, and not just in last-mile form, but in
| coordinated always-on infrastructure form. The
| regulations were not written with this in mind. With an
| active community this fact alone might obviate the need
| for many a regulation.
| thereddaikon wrote:
| Unfortunately the FCC's rules around the Ham bands and digital
| modes ends up restricting a lot of potential for advancement
| and experimentation.
| tlrobinson wrote:
| I assume you're referring to the rule prohibiting "messages
| encoded for the purpose of obscuring their meaning" (e.x.
| encryption).
|
| I don't think it's particularly limiting, as you can still
| use cryptography for purposes other than "obscuring [the
| message's] meaning", e.x. authentication. You just can't
| encrypt the payload.
|
| It's also likely necessary to prevent the bands from being
| overrun with people using them for commercial purposes.
| Steltek wrote:
| Encryption is a nerd sniping/clickbait topic. I would argue
| there are other rules with worse impact:
|
| - Baud rate vs symbol rate vs bandwidth occupied
|
| - No spread spectrum south of ~2.4GHz
|
| - New protocols/modes are a catch-22 of needing to be well
| known to be legal but then how do you create a new one from
| scratch?
|
| - Use-case specific power limits, like radio control.
|
| - "Gotcha" technicality fines like incidental broadcasting
| of music or "fleeting" curse words. Intent and pattern of
| behavior isn't considered.
| provobro wrote:
| That and anyone using this would need a ham radio license
| rmason wrote:
| Getting a technicians license is probably easier than you
| think. I've heard of amateur radio clubs putting on all
| Saturday classes with people taking the test at the end.
| VHF radios aren't expensive, in fact they're importing some
| from China that are dirt cheap.
|
| Course if you want to work on the HF bands then it requires
| a bit more work to get the higher class licenses.
| jjoonathan wrote:
| IMO that's a great way to set up a sandbox: it has built in
| crowd control and a mechanism to keep out flagrant abuse.
|
| Yeah, it doesn't scale to the moon, but that's the whole
| point: it's a proving ground, not a moon rocket.
| danbr wrote:
| > IMO that's a great way to set up a sandbox: it has
| built in crowd control and a mechanism to keep out
| flagrant abuse.
|
| Sadly nothing is really stopping anyone from buying
| radios online and transmitting garbage. Sure the FCC will
| come knocking if someone flagrantly transmits without
| regard for others.
| iszomer wrote:
| Then again, there are people who police themselves and
| others. Here's an interesting story about an
| investigation into a camouflaged jammer:
|
| https://www.youtube.com/watch?v=wZjInmHsWdM
| generalizations wrote:
| It's not that it doesn't scale - it's just there's a
| reason people use letters to communicate and not
| postcards.
|
| People expect a modicum of privacy which ham radio, to
| its detriment, denies.
| thereddaikon wrote:
| Ham radio is not meant for that though. Its expressly
| meant for education and scientific experimentation by
| amateurs. What it actually gets used for is Boomers
| chewing the fat and LARPing as emergency services
| dispatchers mostly but the allocations were put in place
| to allow people to connect with one another and learn the
| science of RF in a practical way.
|
| The sad part is that the FCC has been more interested in
| maintaining the status quo than actually continuing the
| spirit of the hobby. There is nothing experimental or
| ground breaking about talking to someone states away
| using an HF transceiver that cost $4k in analog FM. That
| stopped being innovative 80 years ago. There are a lot of
| interesting things being done with RF that are off limits
| to amateurs because they require a business license.
|
| But you are talking about normal people using radio for
| normal conversations. That's a distinct use case. Its
| something worth discussing, the FCC has lagged behind
| there too but its not the same thing as Ham.
| edrxty wrote:
| It also completely prevents any interesting radio
| experimentation. There isn't anything left on that
| frontier that couldn't be conflated with encryption.
| jmwilson wrote:
| As someone who once believed this, this statement is
| simply not true. Experimentation in ham radio is largely
| about the physical layer, with maybe some layer 2-4 work
| when it comes to building low-scale communications
| infrastructure. Encryption is not implemented at this
| level, and the limitations on encrypted content do not
| impede research into new digital modes or actual radio
| science.
|
| I think it is worth asking why modern digital radio
| standards (e.g. P25, DMR, LTE, 5G) were largely developed
| outside the ham community. My survey level understanding
| is they came from the communication needs of their users
| and are not a natural evolution of something that hams
| would build, with or without encryption. When I was
| researching DMR, there's a lot of stuff that is
| unnecessarily clunky when considering the use case of a
| ham QSO. Conversely, the business users of DMR want more
| structure than what's provided with amateur-designed
| digital modes. With 5G, I think there are some real
| technical and capital barriers, i.e., very few amateurs
| have access to the grade of test equipment needed to
| engineer and experiment with systems at those
| frequencies.
| thereddaikon wrote:
| To your first point I think you are missing their meaning
| a bit. There is actual encryption, like AES. And then
| there are communications methods that aren't open by
| default. The way in which the FCC regulations are penned
| means Ham transmissions can't be private in any way. So
| no just actual encryption but pretty much anyone with a
| compatible transceiver should be able to listen in to
| what you are saying at any time.
|
| That level of permissiveness can be problematic because
| some technologies are by their nature not compliant. FHSS
| comes to mind. Its not encrypted but if you don't know
| know the sequence it might as well be. WiFi, bluetooth
| and most cell protocols use FHSS. So if you wanted to
| experiment with digital data transfer and make it in any
| way robust in a congested area you could not do so as a
| Ham. Its implicitly illegal.
|
| To your second point I agree. DMR, P25, TETRA etc were
| developed with police departments and such in mind. To
| get the full use out of them requires a heavy investment
| infrastructure for trunking systems. And their
| programming models assume a set it and leave it use case
| where the operators are not trained or even savvy to RF
| comms.
|
| This makes them at best clunky for Hams. DMR has caught
| on not because its the best, but I think because its
| easier and cheaper for radio makers to license it. In
| Europe Type 1 is also allowed unlicensed which gives the
| market momentum.
| detaro wrote:
| What's more conflated with encryption than e.g. the level
| of encoding you find in DVB-S or FT-8?
| ajsnigrutin wrote:
| This is a pro... learn some radio stuff, pay a tiny amount
| of money, and get a licence to communicate without the need
| for random providers.
| ajsnigrutin wrote:
| I'm not sure about the FCC, but usually, only encryption is
| prohibited.
|
| Otherwise, there are many data protocols, even new ones
| developed for ham networks, in ~10mbit range for IP, eg:
|
| http://lea.hamradio.si/~s53mv/nbp/nbp.html
| rsync wrote:
| "Texting via APRS has been a thing for about 20 years."
|
| Yes, that's true.
|
| If, by "texting", you mean either:
|
| - A handheld radio attached to a laptop with a serial cable.
|
| - One of two (three ?) models ever produced that allowed you to
| key in APRS with T9 typing on a number pad.
|
| Yep, it's _awesome_.
| hmrr wrote:
| Nailed it. It wasn't and still isn't useful or interesting
| because of the technical overhead of APRS reporting.
|
| Much prefer delving into the weak signal modes. JS8Call is
| interesting http://js8call.com/
|
| I wanted to write an iOS version of it. Just an iPad and a
| radio using the audio interface and you're there. But I don't
| have the time to do it.
| unoti wrote:
| > If, by "texting", you mean either a handheld radio attached
| to a laptop with a serial cable, or one of two (three ?)
| models ever produced that allowed you to key in APRS with T9
| typing...
|
| Actually, you can do a good amount of digital modes radio
| stuff using nothing more than a radio and a smartphone. For
| example, I myself have made a lot of contacts with people
| using PSK31 without a cable, using my iPhone speaker and mic
| near the radio handset.
|
| Digging into how these digital modes work is interesting
| intellectually. It's doable to implement the signal
| processing to implement these modes in code. And once you
| have one mode well-understood, it's also doable to come up
| with ideas on how to improve upon them and make new modes.
| Lots of HN readers would be able to do both of those things,
| and probably enjoy it.
|
| ("Modes" here means a way to communicate information over the
| radio.
|
| https://en.wikipedia.org/wiki/List_of_amateur_radio_modes )
| tdeck wrote:
| I've sent an SMS over the APRS gateway using nothing but a
| cheap handheld radio and the APRSdroid app. The app can emit
| audible data chirps, so you just compose your APRS message,
| hold your phone near the radio, and push the PTT button. Not
| very practical, but there's no custom hardware or connector
| required!
| [deleted]
| squarefoot wrote:
| Why use a complete radio when there are cheap modules that could
| be enclosed along with the logic and screen?
|
| https://www.ebay.com/itm/112889227124
|
| Data sheet here: http://www.dorji.com/docs/data/DRA818U.pdf
|
| Just remember to add an antenna output filter: those modules emit
| all sorts of harmonics (just like many cheap handhelds such as
| Baofengs etc).
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(page generated 2021-11-17 23:01 UTC)