Screeching Across the Spectrum

To be honest, I had a completely different column in mind for this week. However, my previous two columns — When Pirates Ruled the (Air) Waves and Good Vibrations and Border Blasters — seem to have stirred many memories among the devoted followers of my humble Throwback Thursdays offerings (I pride myself on my humility).

For example, having perused and pondered the aforementioned columns, my good friend Joe Farr, who was born and bred (and is still based) in the UK, emailed me to tell me the torturous tale of how he and a friend inadvertently invented a DIY precursor to today’s Wi-Fi.

Based on Joe’s story (presented below), I asked Leonardo.ai to generate an image (shown above). The prompt I gave was: “A teenage boy in the early 1980s in England, in a homemade electronics workshop with a BBC Micro computer connected to a CB radio system sitting on the workbench in front of him.” Keep this image in mind as you read Joe’s message to me as follows:

Hi Max, reading your columns on pirate radio reminded me that I accidentally ran a small pirate radio station for several weeks in 1983.

This was the era of no internet, accompanied by a multitude of different and incompatible home computers. My friend and I both had Acorn BBC Micros (computers), and we often wanted to share programs we’d written with each other. In those days, many houses had a single telephone, but calls were expensive, and the other residents (our parents and siblings) didn’t appreciate us tying up the phone with the sounds of acoustic modems. What we needed was a private communications channel that could be built using pocket money (allowance) funds and requiring no exotic parts.

We came up with an arrangement where we could share our programs and data using our computers’ cassette interface ports, two CB radios, and some software we wrote. This worked great, and I’m sticking to my belief that we invented Wi-Fi.

The only problem was that CB was popular at that time. Living in a busy metropolis, coupled with a limited number of CB channels, made it challenging to maintain clear lines of communication. Also, people didn’t seem to appreciate us tying up a channel with strange screeching sounds.

My brother, who was an electronics genius in my eyes, introduced me to the concept of a simple FM transmitter. These little beasts were simple to build. A basic design requires only two NPN general-purpose transistors and a small handful of cheap, common parts. A transmitter is great, of course, but you also need a receiver.

These transmitters could be tuned from around 87 MHz to 108 MHz, which was accomplished by adjusting a variable capacitor, compressing or bending the tuning coil, and changing the angle at which the device sat on the table. This also happens to be the frequency coverage of a domestic home-use FM receiver.

Our transmitters ran on cheap 9V batteries and generated only a few milliwatts of power. However, if you gave them a nice long antenna, say a couple of feet of wire, you could achieve a reasonable distance with them — maybe 400 to 500 yards.

If you were ingenious enough to connect them to a long wire aerial that ran, say from a bedroom window, all the way down the garden to a tree, then from there across the bottom of several neighbors gardens to another tree, and you’d read the Ladybird book on building a transistor radio and paid attention on how to erect a wire aerial correctly using insulators, you could get a significantly longer range out of them.

Coupled with many evenings of research at the local library in its electronics section, you could perhaps add a 2-transistor RF amplifier to boost the output and increase the range slightly (such as across the city). Finding an unused frequency was tricky — the airwaves were crowded, and nearby police or taxi radios sometimes suffered interference from our transmissions.

We were now in possession of a pretty good long-range communication link. By flicking a switch that swapped from the data cable to a microphone, we also had an audio link. We could place the microphone next to the Hi-Fi and play music to each other. Unfortunately, this wasn’t as private as we’d hoped.

It turned out that we were impacting the local taxi company, which didn’t appreciate the lovely music of Vangelis I’d been playing for my friend. I know this because my sister, who had just returned from the train station via taxi, was laughing that the taxi driver was shouting down the radio, and all he could hear in return was some weird music and strange screeching sounds.

We immediately stopped transmission. We probably should have flung ourselves upon the mercy of the authorities, but we kept our heads down, and nothing came of it. In the UK, the police have now transitioned to their secure Airwave Tetra communication network. Also, most taxis no longer use radios. All this makes the FM band significantly quieter. While illegal to use in some countries, an FM transmitter with a short antenna is a great way to experiment with very low-power transmitters on a budget of a few dollars.

In a follow-up video call, Joe mentioned that there’s a schematic for a simple-to-build FM transmitter on his personal website. During this call, I took a screen capture of today’s Joe, which is shown below. When I shared this image and its computer-generated counterpart with Joe, he responded, “That’s scary… I’m still wearing the same shirt!”

Did anything about Joe’s story leap out at you? My eye was caught by the bit at the beginning where he said: “…we could share computer data between each other using the cassette interface port.”

Although this started with their original CB radio-based system, they later extended it to their FM radio-based implementation. Joe and his friend were both only 18 years old in 1983. I have to say that I am more than impressed to learn that (a) they were the proud possessors of BBC Micros (I dreamed of owning one of these bodacious beauties) and (b) they had the ability to transfer data files between their computers over the radio.

Although there are a few documented cases of people broadcasting computer software or data over radio (including FM or VHF) in the early 1980s, this was a niche, technically challenging, and not widespread activity. In fact, apart from Joe and his friend, I’m aware of only a few other examples as follows:

In Yugoslavia in 1983, a radio show called Ventilator 202 broadcast software over FM for use with the build-it-yourself Galaksija computer. Listeners recorded the broadcast onto cassette tapes and loaded the programs into their home computers. Over time, the show evolved into a hub for software sharing, including user-submitted edits that were rebroadcast.

In the Netherlands, there was a project called BASICODE (from the early 1980s) that aimed to standardize a cassette-data format for sharing BASIC programs via radio broadcasts. The idea was that radio stations would broadcast data in this format, allowing listeners to record it and then load it into their computers.

In England in the early 1980s, Piccadilly Radio (261 medium wave / 97 FM in Manchester) occasionally broadcast computer programs over the airwaves as audio data bursts that listeners could record on cassette and then load into their home computers, such as the ZX Spectrum, BBC Micro, or Commodore 64. Timmy Mallett had a show on Piccadilly Radio called Timmy on the Tranny (where "tranny" was understood to mean "transistor radio" at that time) that sometimes featured these segments as a “bonus” for tech-minded kids. Timmy would say something like “Get your cassette recorders ready!” Then you’d hear the classic modem-like screeching sound as the computer data was played.

But wait, there’s more, because a few UK bands in the early 1980s included computer programs on the B-side of their 7-inch singles. For example, Chris Sievey’s 1983 single Camouflage included a computer program for the ZX Spectrum on its B-Side.

And there’s still more, because one of the more charming and little-remembered quirks of early-1980s British computing culture was the 7-inch flexi-disc, made of thin plastic, which was distributed with magazines such as Computer & Video Games (C&VG), Your Computer, Practical Computing, Personal Computer World, Popular Computing Weekly, and Interface. Readers could play the record on a normal turntable and record the sounds onto a cassette. Alternatively, they could feed the record output directly into the computer’s “EAR” input to load the program (short for “Earphone,” the EAR input was a 3.5 mm audio jack socket used to load programs into the computer from an external audio source — typically a cassette recorder).

As a final aside, Joe informs me that the BBC Micro featured an SAA5050 teletext decoder IC, manufactured by Philips (formerly Signetics). Its primary purpose was to generate text and graphics for the “MODE 7” display, which was the machine’s teletext-compatible screen mode. This device made the BBC Micro 100% compatible with the BBC’s CEEFAX teletext service. This meant that if a user had an optional external teletext decoder attached to their BBC Micro, they could download computer programs from the TV’s CEEFAX.

It's amazing to think how far (and how fast) things have come since those far-off days. Bluetooth was conceived in 1994 and standardized in 1999, while Wi-Fi kicked off in 1997. I remember when signs at restaurants and hotels saying “Free WiFi” were the rare exception — now it’s ubiquitous. There’s even Wi-Fi access on Mount Kilimanjaro, for goodness’ sake.

Another aspect to consider is the use of satellite phones. The first global handheld satellite phone service was launched in 1998 with Iridium. However, these devices initially cost $3,000 or more, with airtime rates ranging from $2 to $10 per minute, depending on the plan and usage. Over the past few years, smartphone manufacturers and satellite/telecom companies have begun incorporating satellite-linked features. These features were initially employed only for tasks like emergency messaging, but they are currently moving toward fully integrated connectivity (voice and data). Future 5G Advanced and 6G standards are expected to integrate satellite connectivity natively, making it as common as Bluetooth, Wi-Fi, and GPS are today.

I don’t know about you, but it seems there’s always something new to learn. As always, I welcome your captivating comments, querulous questions, and sagacious suggestions, all of which you can share on Hackster's "Throwback Thursdays" Discord channel. I look forward to seeing you there.

P.S. Don't forget that you are only a click away from perusing and pondering all of my Throwback Thursdays columns in one place.

P.P.S. Please feel free to email me at max@clivemaxfield.com if you have any questions about this column or if you have any requests or suggestions for future articles.