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Episode 4 – Bitcoin by radio, this can’t be possible!

Watch 23 min

Imagine waking up one morning to find that the internet is down. Not because the router needs a restart, no your government has deliberately pulled the plug. You’ve no idea when it’ll be back online, and in the meantime, you’re cut off from life as you know it. And it’s worth spending a moment here to think how much of your life is internet dependent. And since modern society isn’t big on keeping cash these days and ATMs stock up on only so much paper money at a time, things are going to get real ugly real fast. And if that all sounds like dystopian fear-mongering you only have to go back a month when Myanmar’s military junta imposed multiple internet shutdowns and information blackouts limiting access to Facebook and facebook messenger. This scenario is a real and genuine possibility for many citizens around the world. If cryptocurrencies are to live up to the job of being truly censorship-resistant then could they withstand such drastic censoring?

It’s happening, this is not a drill, if you too are looking for answers about blockchain and cryptocurrency but feel like you’re on the dark side of the moon, then fear not because we’re packing some very big batteries. You’ve found School of Block, let’s get it awnnnn.

Brief history of long distance communication. 

It’s probably hard to imagine a world where we don’t enjoy always-on access to information but that world used to be, well, normal and it really wasn’t that long ago. When I was growing up if I wanted to know what was on at the cinema I had to call up the cinema. If I wanted to go somewhere I had to take a map. Mankind has spent the majority of its existence not having the internet. And you know what, planes didn’t fall out of the sky, we put a man on the moon. We’ve always been communicating over distance and, over the years, humans have proven themselves incredibly resourceful at doing so. 

The issue isn’t so much getting a message from one place to another, attaching meaning to the signal has been much harder and ensuring the veracity of the meaning is really tough.  Egg drops.

So here’s a brief history of humanity’s highlights reel.

Light match. The earliest and crudest form of long range communication was the simple signal fire or smoke signal. Set up somewhere with a good line of sight and light a fire to signal a pre-arranged condition. The fall of Troy was signaled by King Agamemnon to Queen Clytemnestra in Greece using exactly this method. But you know, what if you can’t light a fire, or there’s mist. Problematic. 

In 490 BC the greek soldier Pheidippides runs 26.2 miles to Athens from the battlefield at Marathon to deliver the news “Niki!” (“victory”), then he collapses and dies.  Before this innovation people just walked, but news traveled much slower. And as a side note it gave us the modern marathon race.

335 BC We have the Bull Horn or stentorophonic tube. Basically a massive trumpet. Alexander the Great used one and he could communicate up to 12 miles.

Then we come to the 1830s,  the dawn of the electric age and with it the Electromagnetic Telegraph – it took quite some time for innovation to make these devices useful.  It was originally invented in 1804, but only put into commercial use on Britain’s Great Western Railway in 1839.  Inventor Samuel Morse developed what came to be known as the telegraph and with it the most famous code of them all, Morse code,  in 1837 and drove the Pony Express out of business with a trans-continental telegraph line by 1861.

But then in 1876 Alexander Graham Bell ushered in a new era of voice and sound telecommunication with his prototype telephone. The telephone transmitted actual sound messages and made telecommunication immediate. Not everyone was convinced though. “This ‘telephone’ has too many shortcomings to be seriously considered as a means of communication. The device is inherently of no value to us.” ~ Western Union internal memo, 1876.

1891 AGB imagined the arrival of video calls  “…the day would come when the man at the telephone would be able to see the distant person to whom he was speaking.” 

By the 1920’s we had the first Video Phones –  the technological precursor to the videophone was the teleostereograph machine developed by AT&T’s Bell Labs. By 1927 AT&T had created its earliest electromechanical videophone, called an ikonophone.

Radio waves, also known as Hertzian waves, were first discovered in the late 19th century and were later used for commercial purposes by Guglielmo Marconi in 1896. Although early development was unfruitful, the research and development necessary to improve the radio’s capabilities was boosted by World War I in an effort to create a military communications advantage.

By World War II radio had become a household norm, airing everything from national news to late night soap operas, making radio the most widespread mass communication medium the world had ever seen.

Then we had television and of course the internet but even that has been around longer than you might think. The world is criss-crossed by communication infrastructure, radio masts, fiber optic cables and an ever-increasing soup of satellites whizzing by overhead. So, somewhere in all of this we must have the infrastructure we need, right? Time to do some research.

The big challenge we have here is to create a network that can exist independently of the internet and that’s actually a bit of a challenge at scale. One solution has been created by Blockstream who have literally Bitcoin into space. The Blockstream Satellite network broadcasts the Bitcoin blockchain around the world 24/7 for free, protecting against network interruptions and providing anyone in the world with the opportunity to use Bitcoin. And to use it we’re going to need to install a satellite dish. (drone skit)

Blockstream sell kits including a flat panel antenna as well as a rack-mounted satellite receiver. All of which will set you back about $1200. Only problem… they’re out of stock. So that kinda kills that.  Also, satellites let you receive data without an internet connection, but you can’t use them to send. 

The thing is we all have a sophisticated sending and receiving device in our pockets. A cellphone. So if you could set up something like a mesh network then you could bypass the internet to send data. We found a tweet from Coinsurenz who talked about using Gotenna and the Samourai wallet to send bitcoin. GoTenna and Blockstream have actually partnered to create TxTenna aimed at providing a kind of last mile service for bitcoin transactions. And in theory this looks good. You can buy a pair of Gotenna Mesh devices that pair with your smartphone and allow you to send private relay messages. These are great for keeping a group in contact if they’re out in remote areas. But there’s a problem here. They have a range of a few miles in open areas but only half a mile in built up zones. They’re also battery powered and run for about 27 hours. Now people are running these as part of a global mesh network but where we are, there’s only one. So we’d have to build a network ourselves and that’s going to cost serious money but maybe we’re making this too difficult for ourselves. 

So far we’ve been thinking about replicating the whole network. Maybe we only need to take one part of the process, broadcasting a transaction. And to do that we could simplify our operations to a peer-to-peer model. Effectively that’s like having a cup and some string. 

Now if you’re talking peer-to-peer communication there’s one method that continues to delight hobbyists all over the world. Radio.

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves in a vacuum travel at the speed of light, and in the Earth’s atmosphere at a close, but slightly lower speed.  Different frequencies of radio waves have different propagation characteristics in the Earth’s atmosphere; long waves can diffract around obstacles like mountains and follow the contour of the earth (ground waves), shorter waves can reflect off the ionosphere and return to earth beyond the horizon (skywaves), while much shorter wavelengths bend or diffract very little and travel on a line of sight, so their propagation distances are limited to the visual horizon.

To prevent interference between different users, the artificial generation and use of radio waves is strictly regulated by law, coordinated by an international body called the International Telecommunications Union (ITU), which defines radio waves as “electromagnetic waves of frequencies arbitrarily lower than 3 000 GHz, propagated in space without artificial guide”. So if we travel back to 2017, computer scientist Nick Szabo (the brain behind BitGold the spiritual father of what we now know as Bitcoin) and PhD researcher Elaine Ou explored the topic at Stanford’s Scaling Bitcoin conference, introducing a research project that proposed tethering bitcoin to radio broadcast to secure consensus proofs using weak signal radio propagation. It all sounds fun on paper but could it actually be done? Well, yeah. 

Rodolfo Novak, co-founder of bitcoin hardware startup CoinKite successfully sent Bitcoin from Toronto Canada to Elaine Ou in San Francisco. So, it should be straightforward, we just need a radio. Time to go shopping.


The Tecsun S2000 Desktop Radio is the ultimate desktop listeners radio allowing you to listen to AM, FM, shortwave, longwave and VHF Air Band broadcasts all on the one radio. Large LCD display, it’s got it. Metal rotary knob, you’re goddam right. Signal stength electric pointer watch – you’d better believe it, and what about that rotary AM antenna — don’t get one of those on your new-fangled smartphones do you? Thing is, as I played with my new toy I began to realise I might have made a bit of a cockup.

REALITY CHECK 2: you need a license.

So after some brutal reality checks we realised that we needed to speak to somebody who’d actually done this. After putting out some enquiries we were able to connect with this chap, Sam Patterson who was on the receiving end of a transaction from Rodolfo and he graciously agreed to talk to us. 

Sam, this is a fun idea in theory but are there any real practical use cases for using radio?

What kind of challenges are we going to have to overcome to do this?

Out takes from call with SAM. This is going to be a lot harder than we thought,. 

Regarding the BTC over radio transaction, here’s what you need:

  1. A licensed ham with a radio and antenna willing to send the transaction. 
  2. The band (frequency) being used. This will depend on the distance from sender to receiver, and the time of day (some bands are “open” or “closed” throughout the day based on sun’s influence).
  3. Determine the data type being used. There are various protocols for sending data over the air. Both sender and receiver need to know which they are using. 
  4. A way to receive and decode the signal. WebSDR gives you a way to receive the signal, and their interface allows you to record it, but not a method for decoding the data within. We will need to use software built for this.

When we looked at these pieces of software they were so confusing. And we probably couldn’t use them the way normal ham radio operators use them. Sam’s  recommendation was to record an audio file of the transmission from webSDR, then import the file into the software. Assuming everything worked perfectly it should start decoding. But according to Sam, it rarely does. 

Finally we have to Determine the payload. The simplest possible way to do this is to send along the seed words to a brain wallet. That’s a small amount of data, and it does allow for someone to take control of those funds. 

The sender could also send along a signed transaction, and have the receiver broadcast it on the internet. This is a more likely scenario for real BTC transactions over radio, where the sender doesn’t have internet access but still wants to make a transaction.

The more data sent, the more complexity involved and the more likely part of the message will be dropped, which means it all needs to be sent again. 

A brain wallet is basically a bitcoin wallet secured with a seed phrase that you memorize and that’s it. You can use any combination of words you want. Interestingly a researcher at Bitmex ran an experiment in which eight Bitcoin private keys were created, using passphrases from popular works of fiction and other media. All the Bitcoin was nabbed in a remarkably short amount of time and in one instance they disappeared in just 0.67 seconds. But taken by who, or what? According to the researcher: The speed and nature of the redemption of the funds clearly indicates that people have servers up online 24/7 scanning the blockchain and their respective memory pool’s for weak brainwallets to hack. These servers are likely to have pre-generated many hundreds of thousands of Bitcoin addresses, using text from thousands of published works, music, books, academic papers, magazines, blogs, tweets and other media and then stored these in a database.

Finally Sam advised that communication and patience would be critical and that there was a very good chance it wouldn’t work at all.

So, here’s how we set it up. Sam has his own radio antenna setup forty to fifty feet in the air allowing him to broadcast and receive radio signals. We on the other hand, didn’t. So in order to make the transaction happen we needed to connect to an intermediary with an antenna who was feeding that signal to an internet site where we could then download the data that Sam was sending us and decode it using the software he recommended.

We tried and tried for the next hour but it just wasn’t going to happen. And to make matters worse Sam was about to drop a bomb.”


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