Bitcoin Forum

Ham radio can be used to receive encrypted messages, so it can be used to send and receive bitcoins over very long distances.
Imagine a scenario in the future where only Brazil has internet as we know it today and allows bitcoin to be used.
We could use ham radio using encrypted communications for bitcoin sweep.
Then again, ham radio communication seems easier to restrict than the internet.
By the way, do you think in such scenario would be possible to use an old fashioned modem to connect with internet in Brazil using ham radio?

"HAM" radio is a specific, licensed service with a prohibition on encrypted communications.

I do believe that "high frequency" or "shortwave" radio, which is what you mean, will play a role in human liberty.

Being forced to radio sort of indicates to me a very severe situation.  I would guess that under a situation where free communications were severely restricted, any attempt to carry on data conversations would result in a very quick visit from a drone.

About ten years ago I got interested enough in all the funny noises on radio bands and got an RX320 radio then ported some software to my operating system of choice.  Someone told me that they were 'computers talking' when I was a kid (70's) and I always wondered what they were saying to one another.  I found that there are a lot of modulation types and it is quite possible to receive data from all over the Pacific at least.  I went back to work about that time and have yet to get back into the hobby.

My current belief is that while it might be possible to keep any eye on things like spot prices and such, but again, I imagine that any attempt to actually send would be nothing more than a beacon telling the authorities where to find you.  Or at least your radio gear.

there has existed for somehing like 35 years an analogue modem for 27MHZ, 142MHZ licenced and unlicensed. It's just a little PCB you solder to your mike / speaker points. There are multiple private 24/7 uplinks around the world. so you can mail and surf as you would normally, but slow. Around 2K baud, So try to sync your block chain on that.

As a post apocalyptic internet it's fine.

This sounds really interesting. Any chance on a link to more info?

Yeah but how F*ING long would it take to download the block chain on an hf modem??

regards highly resistent networks and radios...
 what you want is something listening all the time and caching messages.... then able to only transmit shortly before moving...

this could be done with bluetooth or wifi but I've never seen it done well (including serval for android)

So, it's funny this thread came up today because I was just thinking about HAM radio applications for bitcoin.  Transactions over the radio wouldn't be super-feasible using voice modes (but perhaps using digital modes).  They need not be encrypted, just signed.  AFAIK, sending a cryptographically signed message for authentication should be fine since the data is in the clear.  Here's an extensive write-up on the subject:

http://blog.rietta.com/2009/08/authentication-without-encryption-for.html


HAMs could get a vanity bitcoin address with their callsign, and use that to receive donations (like for rare DX), sell products, contribute anonymously to radio clubs/nets, participate in contests where rewards are sent via bitcoin, etc.  In fact, I'm generating one for my callsign right now (sold all my video cards, so it's SLOOWWWW - will take 2 hours). 

If I manage to get my radio going (HF), I'll post in here, and if another HAM is interested I'd love to send some µBTC to them after a radio negotiation.  The HAM community is VERY technical, and has a sort of libertarian streak at times, so they should welcome BTC IMHO.

I think it would be great to try to get the HAM community involved, and it didn't dawn on me about the libertarian streak, but I bet you are right.

I do believe that it is for all intents and purposes pretty hopeless to do anything like P2P Bitcoin stuff over radio.  Most computer folks will argue that the system is not to bloated as long as 10GB data bandwidths still works...in theory.  There might be some room for thin clients and possibly for close geography links (like say a couple hundred meters across the boarder to a free country such as Ecuador) but after thinking about it a bit, I've concluded that it's not the best hope if/when free communications between individuals and labeled a terrorist act and such.

Although I've not studied the subject in depth I bet you are wrong in the conjecture of the meaning of Section 97.113.  Both in theory, and more importantly, in practice.  Thanks to some incredible work by some of our cypherpunk forefathers there was a gaping hole blown in the Internet part of the spectrum but I fully expect that to be patched up at some point and for our leaderships to be more careful going forward so that that does not happen again.

Here you go, it's called a TNC: http://www.coolcircuit.com/gadgets/category/ham-radio/ There are 100+ pages about them.

Apparently there are also micro processor versions now...

BTW there are also free HAM satellite repeters for voice and data: http://www.amsat.org/amsat-new/index.php

You'd need about 2kbps to download seven 1MB blocks an hour.  That's a lot of bandwidth 24/7/365 on a global HF network.  I think the Bitsat project and the use of UHF and SHF for a lot more relative bandwidth is the best solution for a global wireless network - https://bitcointalk.org/index.php?topic=334701.0

Most certainly interesting. But yes, this would indicate a very very severe problem.

How would http://www.short-wave.info/ stations work for 2kbps?

Well I'm pretty up to date on stuff and I've never even heard of ham radio so I'm going to look into it. Just by following the thread though, you're not saying to use ham radio as a replacement for the bitcoin network right?  Because that needs miners Rex. You're just talking about using it to send certain transactions?  Or data too?

So 6.67 minutes to download a 1MB block at 2.5kbps.  You'd need to operate on two channels so that you had a 2.5kbps receive and 2.5kbps transmit at the same time.

So there's the receiving the blockchain side, what about just sending transactions and not bothering to wait for an ack?

It seems like there would need to be a worldwide net of receiving nodes with internet access listening for TXes on whatever frequencies we/the ITU decides are standard, then if 2 or more are able to clearly receive decodable TXes from the same sender, the better. Byte sizes of my last 5 received TX: 440 225 257 374 439. Since I don't have any higher tech, let me run the 440 byte hex through a morse code generator at 80 WPM (assuming digital decode) and see how long it takes. 3 mins 20 secs.

Or on Q15X25 http://www.calctool.org/CALC/prof/computing/transfer_time says 1.37500 seconds.

 HAM is basically regulating the airwaves that anybody can tune in, isn't it?

Yes, anyone can tune in to listen to ham radio, but it's important that we have parts of the radio spectrum to ourselves, otherwise all frequencies from DC to daylight would be licensed for commercial and public safety (much of which isn't listenable without buying horrifically expensive gear, if it isn't completely encrypted for no reason other than to eliminate transparency) use. US.gov doesn't really make much from ham radio, and could easily say "fuck it, this is worthless, time to make some money, bye hams".

The only fees they collect are for the radio equivalent of vanity license plates; vanity callsigns. To get a randomly assigned callsign is free, but most of them are hard to copy under poor radio conditions, so some of us get vanities. Currently they're $16.10 for 10 years, but the FCC is seeking to increase it: http://w6sg.net/site/?p=1270

Convert address into audio, pass audio through radio, pay address

sending the blockchain through sound.. hmm thats the equivalent to using dialup to download a 20gb file. but without the ability to check packets are complete without errors.

useful for sending signed tx's. but not useful for whole blockchains. so keep this concept to signed tx's only

a packet radio that is specifically listening for signed bitcoin transactions to be sent to the network.

Not a ham operator but I've looked into it a bit. Problem is it has to little bandwidth for full nodes. It could possibly be used in a SPV manner for linking a specific payment terminal to a radio connected to a full node. But considering the block limit today is 1MB and that will have to be increased I don't think it can be used for the kind of emergency network I'm thinking of.

Look up the TNC-PI for how packet radio can be realised.

There's some discussion here https://bitcointalk.org/index.php?topic=74924.0

 I don't think anyone has tried this yet. And, he hasn't said this to my knowledge, but I get the impression that MoonShadow may be a HAM so you might ask him.

6 blocks/hr * 1048576 * 8 = 50331648 bits/hr

50331648 bits/hr / 3600 seconds = 13981 bps = 13.981 kbps   (with no additional overhead)

For 7 blocks/hr, 16.311 kbps   (with no additional overhead)

These rates exceed conventionally available AX.25 packet radio / TNC throughputs for HF and VHF ham bands (generally 300 baud FSK for HF, and 1200 baud AFSK or 9600 baud AFSK for VHF/UHF).  Either use of higher frequency bands or a custom modulation format that would tend to have a bandwidth exceeding amateur radio rules in most ITU countries on HF, VHF and UHF frequencies would be needed.  At that point you might as well just set up a 900MHz, 2.4GHz or 5GHz 802.11 link.



$10 to $15 for a Realtek-based DVB-T USB receiver dongle used as an SDR (software defined radio), and you can receive whatever you want from 24 to 1766MHz (in the case of versions of the dongle using an R820T RF front end).
http://sdr.osmocom.org/trac/wiki/rtl-sdr (http://sdr.osmocom.org/trac/wiki/rtl-sdr)

Woah, I want that but I think we'd all prefer it to be plug-n-play on all operating systems...

Yeah it looks like the full blockchain over HF is a no go'er.  We'd be best supporting the Bitcoins in Space project - https://bitcointalk.org/index.php?topic=334701.0 - Or in setting up a project to build a cheap WiFi mesh-networking router that can hold bitcoind.  As even the public PMR446 UHF band only permits 3.6kbit/s per channel.  Although possibly maybe we could use the unlicensed 900MHz 33cm UHF band for a custom mesh-network with better propagation than the 2.4GHz 802.11n.  There's off the shelf license free 802.11g 900MHz 33cm UHF equipment like this - http://www.alvarion.com/products/product-portfolio/breezeaccess/breezeaccess-900 - and this - http://www.xgtechnology.com/xMax-articles/xmax-system-overview.html - That we could attach a cheap lightweight nettop too to hold bitcoind.

There's also the new 802.11ah: WiFi Standard for 900MHz coming out.


This may work better for WiFi mesh-networks.

how about a radio that calculates the frequency randomly for every packet by continuously SHA256 hashing an initial seed.
that way if you want to communicate with someone who knows the initial seed you can do it without the authorities knowing which frequencies are being used.

ex-G0--F (removed my call sign) here... i was into Ham radio 20 year ago (ouch), I used to be on Packet Radio on 144mhz and also did HF packet (which didn't work very well).  I used to run a repeater 20 miles away which used to pass traffic to somewhere else, it was okay for listing your 'email' as it was back then, took ages to get a message and the packet radio would be stuffed if it did hear another transmission.  If I was at the repeater and turned on the radio you would hear hundreds of packet radios trying to transmit all the time, it was that slow, just a big pile up of radio transmissions and the strongest would be king.  The problem was is the amount of time it took before re-transmission.

Here is a video, about 4 minutes in you can hear the signals.
https://www.youtube.com/watch?v=9dfqPQui4NU

Other technologies like RTTY/PACTOR/AMTOR could allow you to do it over HF, AMTOR had the abilities to locking a connection so you could keep talking and have mistakes corrected. This is PACTOR, I didn't use it myself but you see a file transfer going on https://www.youtube.com/watch?v=RaAKJRfaKiE

If Kryptoradio (http://www.coindesk.com/bitcoiners-finland-send-cryptocurrency-radio) in Finland can do broadcasts in only a 7.5kbps channel.  Then instead of only broadcasting in UHF line of site. The same service could broadcast on SW/LW/MW over digital AM to much larger regions from a single transmitter using Digital Radio Mondiale (https://en.wikipedia.org/wiki/Digital_Radio_Mondiale) technology.  A single LW transmitter could potentially give coverage to the whole of Scandinavia. 

Using the Digital Radio Mondiale (https://en.wikipedia.org/wiki/Digital_Radio_Mondiale) codec you could broadcast =>7.1kbps over a 5kHz channel on SW/MW/LW.  Although renting SW transmitter broadcast time costs around $25k (http://www.wwrb.org/ptime.php) per month for 24/7/365 broadcasts.  5kHZ though is about half the bandwidth that AM stations use on MW.

Another idea to look at terrestrial broadcasts although this time with full duplex is UHF IEEE 802.11ah (https://en.wikipedia.org/wiki/IEEE_802.11ah) meshnetworks.  With a good external antenna you could get very good local range at 900Mhz so it could really work well for mesh-networking.  The first IEEE 802.11ah chips are supposed to come out next year while the protocol should be finalised by 2016.  Plus it's an unlicensed band so no one would need a ham license to set up a low power node.