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An Emulated Stroll Down Macintosh Memory Lane

Screenshot of "Frame of Preference"

If you’re into Macs, you’ll always remember your first. Maybe it was the revolutionary classic of 1984 fame, perhaps it was the adorable G3 iMac in 1998, or even a shiny OS X machine in the 21st century. Whichever it is, you’ll find it emulated in [Marcin Wichary]’s essay “Frame of preference: A history of Mac settings, 1984–2004” — an exploration of the control panel and its history.

Image of PowerBook showing the MacOS 8.0 desktop.
That’s not a photograph, it’s an emulator. (At least on the page. Here, it’s a screenshot.)

[Marcin] is a UI designer as well as an engineer and tech historian, and his UI chops come out in full force, commenting and critiquing Curputino’s coercions. The writing is excellent, as you’d expect from the man who wrote the book on keyboards, and it provides a fascinating look at the world of retrocomputing through the eyes of a designer. That design-focused outlook is very apropos for Apple in particular. (And NeXT, of course, because you can’t tell the story of Apple without it.)

There are ten emulators on the page, provided by [Mihai Parparita] of Infinite Mac. It’s like a virtual museum with a particularly knowledgeable tour guide — and it’s a blast, getting to feel hands-on, the design changes being discussed. There’s a certain amount of gamification, with each system having suggested tasks and a completion score when you finish reading. There are even Easter eggs.

This is everything we wish the modern web was like: the passionate deep-dives of personal sites on the Old Web, but enhanced and enabled by modern technology. If you’re missing those vintage Mac days and don’t want to explore them in browser, you can 3D print your own full-size replica, or a doll-sized picoMac.

 

One Laptop Manufacturer Had To Stop Janet Jackson Crashing Laptops

There are all manner of musical myths, covering tones and melodies that have effects ranging from the profound to the supernatural. The Pied Piper, for example, or the infamous “brown note.”

But what about a song that could crash your laptop just by playing it? Even better, a song that could crash nearby laptops in the vicinity, too? It’s not magic, and it’s not a trick—it was just a punchy pop song that Janet Jackson wrote back in 1989.

Rhythm Nation

As told by Microsoft’s Raymond Chen, the story begins in the early 2000s during the Windows XP era. Engineers at a certain OEM laptop manufacturer noticed something peculiar. Playing Janet Jackson’s song Rhythm Nation through laptop speakers would cause the machines to crash. Even more bizarrely, the song could crash nearby laptops that weren’t even playing the track themselves, and the effect was noted across laptops of multiple manufacturers.

Rhythm Nation was a popular song from Jackson’s catalog, but nothing about it immediately stands out as a laptop killer. 

After extensive testing and process of elimination, the culprit was identified as the audio frequencies within the song itself. It came down to the hardware of the early 2000s laptops in question. These machines relied on good old mechanical hard drives. Specifically, they used 2.5-inch 5,400 RPM drives with spinning platters, magnetic heads, and actuator arms.

The story revolves around 5,400 RPM laptop hard drives, but the manufacturer and model are not public knowledge. No reports have been made of desktop PCs or hard disks suffering the same issue. Credit: Raimond Spekking, CC BY-SA 4.0

Unlike today’s solid-state drives, these components were particularly susceptible to physical vibration. Investigation determined that something in Rhythm Nation was hitting a resonant frequency of some component of the drive. When this occurred, the drive would be disturbed enough that read errors would stack up to the point where it would trigger a crash in the operating system. The problem wasn’t bad enough to crash the actual hard drive head into the platters themselves, which would have created major data loss. It was just bad enough to disrupt the hard drive’s ability to read properly, to the point where it could trigger a crash in the operating system.

A research paper published in 2018 investigated the vibrational characteristics of a certain model of 2.5-inch laptop hard drive. It’s not conclusive evidence, and has nothing to do with the Janet Jackson case, but it provides some potentially interesting insights as to why similar hard drives failed to read when the song was played. Credit: Research paper

There was a simple workaround for this problem, that was either ingenious or egregious depending on your point of view. Allegedly, the OEM simply whipped up a notch filter for the audio subsystem to remove the offending frequencies. The filter apparently remained in place from the then-contemporary Windows XP up until at least Windows 7. At this point, Microsoft created a new rule for “Audio Processing Objects” (APO) which included things like the special notch filter. The rule stated that all of these filters must be able to be switched off if so desired by the user. However, the story goes that the manufacturer gained a special exception for some time to leave their filter APO on at all times, to prevent users disabling it and then despairing when their laptops suddenly started crashing unexpectedly during Janet Jackson playlists.

As for what made Rhythm Nation special? YouTuber Adam Neely investigated, and came up with a compelling theory. Having read a research paper on the vibrational behavior of a 2.5-inch 5,400 RPM laptop hard disk, he found that it reported the drive to have its largest vibrational peak at approximately 87.5 Hz.  Meanwhile, he also found that Rhythm Nation had a great deal of energy at 84.2 Hz. Apparently, the recording had been sped up a touch after the recording process, pushing the usual low E at 82 Hz up slightly higher. The theory being that the mild uptuning in Rhythm Nation pushed parts of the song close enough to the resonant frequency of some of the hard drive’s components to give them a good old shaking, causing the read errors and eventual crashes.

It’s an interesting confluence of unintended consequences. A singular pop song from 1989 ended up crashing laptops over a decade later, leading to the implementation of an obscure and little-known audio filter. The story still has holes—nobody has ever come forward to state officially which OEM was involved, and which precise laptops and hard drives suffered this problem. That stymies hopes for further research and recreation of this peculiarity. Nevertheless, it’s a fun tech tale from the days when computers were ever so slightly more mechanical than they are today.

 

Simulating Empires with Procedurally Generated History

Procedural generation is a big part of game design these days. Usually you generate your map, and [Fractal Philosophy] has decided to go one step further: using a procedurally-generated world from an older video, he is procedurally generating history by simulating the rise and fall of empires on that map in a video embedded below.

Now, lacking a proper theory of Psychohistory, [Fractal Philosophy] has chosen to go with what he admits is the simplest model he could find, one centered on the concept of “solidarity” and based on the work of [Peter Turchin], a Russian-American thinker. “Solidarity” in the population holds the Empire together; external pressures increase it, and internal pressures decrease it. This leads to an obvious cellular automation type system (like Conway’s Game of Life), where cells are evaluated based on their nearest neighbors: the number of nearest neighbors in the empire goes into a function that gives the probability of increasing or decreasing the solidarity score each “turn”. (Probability, in order to preserve some randomness.) The “strength” of the Empire is given by the sum of the solidarity scores in every cell.

Each turn, Empires clash, with the the local solidarity, sum strength, and distance from Imperial center going into determining who gains or loses territory. It is a simple model; you can judge from the video how well it captures the ebb and flow of history, but we think it did surprisingly well all things considered. The extra 40-minute video of the model running is oddly hypnotic, too.

3D model of an Alpaca next to a Llama
In v2 of the model, one of these fluffy creatures will betray you.

After a dive into more academic support for the main idea, and a segue into game theory and economics, a slight complication is introduced later in the video, dividing each cell into two populations: “cooperators” or “selfish” individuals.

This allows for modeling of internal conflicts between the two groups. This hitch gives a very similar looking map at the end of its run, although has an odd quirk that it automatically starts with a space-filling empire across the whole map that quickly disintegrates.

Unfortunately, the model not open-source, but the ideas are discussed in enough detail that one could probably produce a very similar algorithm in an afternoon. For those really interested, [Fractal Philosophy] does offer a one-time purchase through his Patreon. It also includes the map-generating model from his last video.

We’re much more likely to talk about simulating circuits, or feature projects that use fluid simulations here at Hackaday, but this hack of a history model

 

The Rise And The Fall Of The Mail Chute

As the Industrial Age took the world by storm, city centers became burgeoning hubs of commerce and activity. New offices and apartments were built higher and higher as density increased and skylines grew ever upwards. One could live and work at height, but this created a simple inconvenience—if you wanted to send any mail, you had to go all the way down to ground level.

In true American fashion, this minor inconvenience would not be allowed to stand. A simple invention would solve the problem, only to later fall out of vogue as technology and safety standards moved on. Today, we explore the rise and fall of the humble mail chute.

Going Down

Born in 1848 in Albany, New York, James Goold Cutler would come to build his life in the state. He lived and worked in the growing state, and as an architect, he soon came to identify an obvious problem. For those occupying higher floors in taller buildings, the simple act of sending a piece of mail could quickly become a tedious exercise. One would have to make their way all the way to a street level post box, which grew increasingly tiresome as buildings grew ever taller.

Cutler’s original patent for the mail chute. Note element G – a hand guard that prevented people from reaching into the chute to grab mail falling from above. Security of the mail was a key part of the design. Credit: US Patent, public domain

Cutler saw that there was an obvious solution—install a vertical chute running through the building’s core, add mail slots on each floor, and let gravity do the work. It then became as simple as dropping a letter in, and down it would go to a collection box at the bottom, where postal workers could retrieve it during their regular rounds. Cutler filed a patent for this simple design in 1883. He was sure to include a critical security feature—a hand guard behind each floor’s mail chute. This was intended to stop those on lower levels reaching into the chute to steal the mail passing by from above. Installations in taller buildings were also to be fitted with an “elastic cushion” in the bottom to “prevent injury to the mail” from higher drop heights.

A Cutler Receiving Box that was built in 1920. This box would have lived at the bottom of a long mail chute, with the large door for access by postal workers. The brass design is typical of the era. Credit: National Postal Museum, CC0

One year later, the first installation went live in the Elwood Building, built in Rochester, New York to Cutler’s own design. The chute proved fit for purpose in the seven-story building, but there was a problem. The collection box at the bottom of Cutler’s chute was seen by the postal authorities as a mailbox. Federal mail laws were taken quite seriously, then as now, and they stated that mailboxes could only be installed in public buildings such as hotels, railway stations, or government facilities. The Elwood was a private building, and thus postal carriers refused to service the collection box.

It consists of a chute running down through each story to a mail box on the ground floor, where the postman can come and take up the entire mail of the tenants of the building. A patent was easily secured, for nobody else had before thought of nailing four boards together and calling it a great thing.

Letters could be dropped in the apertures on the fourth and fifth floors and they always fell down to the ground floor all right, but there they stated. The postman would not touch them. The trouble with the mail chute was the law which says that mail boxes shall be put only in Government and public buildings.

The Sun, New York, 20 Dec 1886

Cutler’s brilliantly simple invention seemed dashed at the first hurdle. However, rationality soon prevailed. Postal laws were revised in 1893, and mail chutes were placed under the authority of the US Post Office Department. This had important security implications. Only post-office approved technicians would be allowed to clear mail clogs and repair and maintain the chutes, to ensure the safety and integrity of the mail.

The Cutler Mail chutes are easy to spot at the Empire State Building. Credit: Teknorat, CC BY-SA 2.0

With the legal issues solved, the mail chute soared in popularity. As skyscrapers became ever more popular at the dawn of the 20th century, so did the mail chute, with over 1,600 installed by 1905. The Cutler Manufacturing Company had been the sole manufacturer reaping the benefits of this boom up until 1904, when the US Post Office looked to permit competition in the market. However, Cutler’s patent held fast, with his company merging with some rivals and suing others to dominate the market. The company also began selling around the world, with London’s famous Savoy Hotel installing a Cutler chute in 1904. By 1961, the company held 70 percent of the mail chute market, despite Cutler’s passing and the expiry of the patent many years prior.

The value of the mail chute was obvious, but its success was not to last. Many companies began implementing dedicated mail rooms, which provided both delivery and pickup services across the floors of larger buildings. This required more manual handling, but avoided issues with clogs and lost mail and better suited bigger operations. As postal volumes increased, the chutes became seen as a liability more than a convenience when it came to important correspondence. Larger oversized envelopes proved a particular problem, with most chutes only designed to handle smaller envelopes. A particularly famous event in 1986 saw 40,000 pieces of mail stuck in a monster jam at the McGraw-Hill building, which took 23 mailbags to clear. It wasn’t unusual for a piece of mail to get lost in a chute, only to turn up many decades later, undelivered.

An active mail chute in the Law Building in Akron, Ohio. The chute is still regularly visited by postal workers for pickup. Credit: Cards84664, CC BY SA 4.0
Mail chutes were often given fine, detailed designs befitting the building they were installed in. This example is from the Fitzsimons Army Medical Center in Colorado. Credit: Mikepascoe, CC BY SA 4.0

The final death knell for the mail chute, though, was a safety matter. Come 1997, the National Fire Protection Association outright banned the installation of new mail chutes in new and existing buildings. The reasoning was simple. A mail chute was a single continuous cavity between many floors of a building, which could easily spread smoke and even flames, just like a chimney.

Despite falling out of favor, however, some functional mail chutes do persist to this day. Real examples can still be spotted in places like the Empire State Building and New York’s Grand Central station. Whether in use or deactivated, many still remain in older buildings as a visible piece of mail history.

Better building design standards and the unstoppable rise of email mean that the mail chute is ultimately a piece of history rather than a convenience of our modern age. Still, it’s neat to think that once upon a time, you could climb to the very highest floors of an office building and drop your important letters all the way to the bottom without having to use the elevator or stairs.

Collage of mail chutes from Wikimedia Commons, Mark Turnauckas, and Britta Gustafson.

Just for Laughs: Charlie Douglass and the Laugh Track

I ran into an old episode of Hogan’s Heroes the other day that stuck me as odd. It didn’t have a laugh track. Ironically, the show was one where two pilots were shown, one with and one without a laugh track. The resulting data ensured future shows would have fake laughter. This wasn’t the pilot, though, so I think it was just an error on the part of the streaming service.

However, it was very odd. Many of the jokes didn’t come off as funny without the laugh track. Many of them came off as cruel. That got me to thinking about how they had to put laughter in these shows to begin with. I had my suspicions, but was I way off!

Well, to be honest, my suspicions were well-founded if you go back far enough. Bing Crosby was tired of running two live broadcasts, one for each coast, so he invested in tape recording, using German recorders Jack Mullin had brought back after World War II. Apparently, one week, Crosby’s guest was a comic named Bob Burns. He told some off-color stories, and the audience was howling. Of course, none of that would make it on the air in those days. But they saved the recording.

A few weeks later, either a bit of the show wasn’t as funny or the audience was in a bad mood. So they spliced in some of the laughs from the Burns performance. You could guess that would happen, and that’s the apparent birth of the laugh track. But that method didn’t last long before someone — Charley Douglass — came up with something better.

Sweetening

The problem with a studio audience is that they might not laugh at the right times. Or at all. Or they might laugh too much, too loudly, or too long. Charley Douglass developed techniques for sweetening an audio track — adding laughter, or desweetening by muting or cutting live laughter. At first, this was laborious, but Douglass had a plan.

He built a prototype machine that was a 28-inch wooden wheel with tape glued to its perimeter. The tape had laughter recordings and a mechanical detent system to control how much it played back.

Douglass decided to leave CBS, but the prototype belonged to them. However, the machine didn’t last very long without his attention. In 1953, he built his own derivative version and populated it with laughter from the Red Skelton Show, where Red did pantomime, and, thus, there was no audio but the laughter and applause.

Do You Really Need It?

There is a lot of debate regarding fake laughter. On the one hand, it does seem to help. On the other hand, shouldn’t people just — you know — laugh when something’s funny?

There was concern, for example, that the Munsters would be scary without a laugh track. Like I mentioned earlier, some of the gags on Hogan’s Heroes are fine with laughter, but seem mean-spirited without.

Consider the Big Bang theory. If you watch a clip (below) with no laugh track, you’ll notice two things. First, it does seem a bit mean (as a commenter said: “…like a bunch of people who really hate each other…” The other thing you’ll notice is that they pause for the laugh track insertion, which, when there is no laughter, comes off as really weird.

Laugh Monopoly

Laugh tracks became very common with most single-camera shows. These were hard to do in front of an audience because they weren’t filmed in sequence. Even so, some directors didn’t approve of “mechanical tricks” and refused to use fake laughter.

Even multiple-camera shows would sometimes want to augment a weak audience reaction or even just replace laughter to make editing less noticeable. Soon, producers realized that they could do away with the audience and just use canned laughter. Douglass was essentially the only game in town, at least in the United States.

The Douglass device was used on all the shows from the 1950s through the 1970s. Andy Griffith? Yep. Betwitched? Sure. The Brady Bunch? Of course. Even the Munster had Douglass or one of his family members creating their laugh tracks.

One reason he stayed a monopoly is that he was extremely secretive about how he did his work. In 1960, he formed Northridge Electronics out of a garage. When called upon, he’d wheel his invention into a studio’s editing room and add laughs for them. No one was allowed to watch.

You can see the original “laff box” in the videos below.

The device was securely locked, but inside, we now know that the machine had 32 tape loops, each with ten laugh tracks. Typewriter-like keys allowed you to select various laughs and control their duration and intensity,

In the background, there was always a titter track of people mildly laughing that could be made more or less prominent. There were also some other sound effects like clapping or people moving in seats.

Building a laugh track involved mixing samples from different tracks and modulating their amplitude. You can imagine it was like playing a musical instrument that emits laughter.

Before you tell us, yes, there seems to be some kind of modern interface board on the top in the second video. No, we don’t know what it is for, but we’re sure it isn’t part of the original machine.

The original laff box wound up appearing on Antiques Roadshow where someone had bought it at a storage locker auction.

End of an Era

Of course, all things end. As technology got better and tastes changed, some companies — notably animation companies — made their own laugh tracks. One of Douglass’ protégés started a company, Sound One, that used better technology to create laughter, including stereo recordings and cassette tapes.

Today, laugh tracks are not everywhere, but you can still find them and, of course, they are prevalent in reruns. The next time you hear one, you’ll know the history behind that giggle.

If you want to build a more modern version of the laff box, [smogdog] has just the video for you, below.

History of Forgotten Moon Bases

If you were alive when 2001: A Space Odyssey was in theaters, you might have thought it didn’t really go far enough. After all, in 1958, the US launched its first satellite. The first US astronaut went up in 1961. Eight years later, Armstrong put a boot on the moon’s surface. That was a lot of progress for 11 years. The movie came out in 1968, so what would happen in 33 years? Turns out, not as much as you would have guessed back then. [The History Guy] takes us through a trip of what could have been if progress had marched on after those first few moon landings. You can watch the video below.

The story picks up way before NASA. Each of the US military branches felt like it should take the lead on space technology. Sputnik changed everything and spawned both ARPA and NASA. The Air Force, though, had an entire space program in development, and many of the astronauts for that program became NASA astronauts.

The Army also had its own stymied space program. They eventually decided it would be strategic to develop an Army base on the moon for about $6 billion. The base would be a large titanium cylinder buried on the moon that would house 12 people.

The base called for forty launches in a single year before sending astronauts, and then a stunning 150 Saturn V launches to supply building materials for the base. Certainly ambitious and probably overly ambitious, in retrospect.

There were other moon base plans. Most languished with little support or interest. The death knell, though, was the 1967 Outer Space Treaty, which forbids military bases on the moon.

While we’d love to visit a moon base, we are fine with it not being militarized. We also want our jet packs.

Watkin’s Tower: London’s Failed Eiffel Tower

The city of London is no stranger to tall constructions today, but long before the first skyscrapers would loom above its streets, Watkin’s Tower was supposed to be the tallest structure in not only London but also the entirety of the UK. Inspired by France’s recently opened Eiffel tower, railway entrepreneur and Member of Parliament [Sir Edward Watkin] wanted to erect a structure that would rival the Eiffel tower, as part of a new attraction park to be constructed near the Middlesex hamlet of Wembley. In a retrospective, [Rob’s London] channel takes a look at what came to be known as Watkin’s Folly among other flattering names.

The first stage of Watkin's Tower at Wembley Park. The only to be ever completed. (Source: Wikimedia)
The first stage of Watkin’s Tower at Wembley Park. The only to be ever completed. (Source: Wikimedia)

After [Gustave Eiffel], the architect of the Eiffel tower recused himself, a design competition was held for a tower design, with the Illustrated Catalogue of the 68 designs submitted available for our perusal. The winner turned out to be #37, an eight-legged, 366 meter tall tower, much taller than the 312.2 meter tall Eiffel tower, along with multiple observation decks and various luxuries to be enjoyed by visitors to Wembley Park.

Naturally, [Watkin] commissioned a redesign to make it cheaper, which halved the number of legs, causing subsidence of the soil and other grievances later on. Before construction could finish, the responsible company went bankrupt and the one constructed section was demolished by 1907. Despite this, Wembley Park was a success and remains so to this day with Wembley Stadium built where Watkin’s Folly once stood.

Crowdsourcing SIGINT: Ham Radio at War

I often ask people: What’s the most important thing you need to have a successful fishing trip? I get a lot of different answers about bait, equipment, and boats. Some people tell me beer. But the best answer, in my opinion, is fish. Without fish, you are sure to come home empty-handed.

On a recent visit to Bletchley Park, I thought about this and how it relates to World War II codebreaking. All the computers and smart people in the world won’t help you decode messages if you don’t already have the messages. So while Alan Turing and the codebreakers at Bletchley are well-known, at least in our circles, fewer people know about Arkley View.

The problem was apparent to the British. The Axis powers were sending lots of radio traffic. It would take a literal army of radio operators to record it all. Colonel Adrian Simpson sent a report to the director of MI5 in 1938 explaining that the three listening stations were not enough. The proposal was to build a network of volunteers to handle radio traffic interception.

That was the start of the Radio Security Service (RSS), which started operating out of some unused cells at a prison in London. The volunteers? Experienced ham radio operators who used their own equipment, at first, with the particular goal of intercepting transmissions from enemy agents on home soil.

At the start of the war, ham operators had their transmitters impounded. However, they still had their receivers and, of course, could all read Morse code. Further, they were probably accustomed to pulling out Morse code messages under challenging radio conditions.

Over time, this volunteer army of hams would swell to about 1,500 members. The RSS also supplied some radio gear to help in the task. MI5 checked each potential member, and the local police would visit to ensure the applicant was trustworthy. Keep in mind that radio intercepts were also done by servicemen and women (especially women) although many of them were engaged in reporting on voice communication or military communications.

Early Days

The VIs (voluntary interceptors) were asked to record any station they couldn’t identify and submit a log that included the messages to the RSS.

Arkey View ([Aka2112] CC-BY-SA-3.0)
The hams of the RSS noticed that there were German signals that used standard ham radio codes (like Q signals and the prosign 73). However, these transmissions also used five-letter code groups, a practice forbidden to hams.

Thanks to a double agent, the RSS was able to decode the messages that were between agents in Europe and their Abwehr handlers back in Germany (the Abwehr was the German Secret Service) as well as Abwehr offices in foreign cities. Later messages contained Enigma-coded groups, as well.

Between the RSS team’s growth and the fear of bombing, the prison was traded for Arkley View, a large house near Barnet, north of London. Encoded messages went to Bletchley and, from there, to others up to Churchill. Soon, the RSS had orders to concentrate on the Abwehr and their SS rivals, the Sicherheitsdienst.

Change in Management

In 1941, MI6 decided that since the RSS was dealing with foreign radio traffic, they should be in charge, and thus RSS became SCU3 (Special Communications Unit 3).

There was fear that some operators might be taken away for normal military service, so some operators were inducted into the Army — sort of. They were put in uniform as part of the Royal Corps of Signals, but not required to do very much you’d expect from an Army recruit.

Those who worked at Arkley View would process logs from VIs and other radio operators to classify them and correlate them in cases where there were multiple logs. One operator might miss a few characters that could be found in a different log, for example.

Going 24/7

National HRO Receiver ([LuckyLouie] CC-BY-SA-3.0)
It soon became clear that the RSS needed full-time monitoring, so they built a number of Y stations with two National HRO receivers from America at each listening position. There were also direction-finding stations built in various locations to attempt to identify where a remote transmitter was.

Many of the direction finding operators came from VIs. The stations typically had four antennas in a directional array. When one of the central stations (the Y stations) picked up a signal, they would call direction finding stations using dedicated phone lines and send them the signal.

Map of the Y-stations (interactive map at the Bletchley Park website)

The operator would hear the phone signal in one ear and the radio signal in the other. Then, they would change the antenna pattern electrically until the signal went quiet, indicating the antenna was electrically pointing away from the signals.

The DF operator would hear this signal in one earpiece. They would then tune their radio receiver to the right frequency and match the signal from the main station in one ear to the signal from their receiver in the other ear. This made sure they were measuring the correct signal among the various other noise and interference. The DF operator would then take a bearing by rotating the dial on their radiogoniometer until the signal faded out. That indicated the antenna was pointing the wrong way which means you could deduce which way it should be pointing.

The central station could plot lines from three direction finding stations and tell the source of a transmission. Sort of. It wasn’t incredibly accurate, but it did help differentiate signals from different transmitters. Later, other types of direction-finding gear saw service, but the idea was still the same.

Interesting VIs

Most of the VIs, like most hams at the time, were men. But there were a few women, including Helena Crawley. She was encouraged to marry her husband Leslie, another VI, so they could be relocated to Orkney to copy radio traffic from Norway.

In 1941, a single VI was able to record an important message of 4,429 characters. He was bedridden from a landmine injury during the Great War. He operated from bed using mirrors and special control extensions. For his work, he receive the British Empire Medal and a personal letter of gratitude from Churchill.

Results

Because of the intercepts of the German spy agency’s communications, many potential German agents were known before they arrived in the UK. Of about 120 agents arriving, almost 30 were turned into double agents. Others were arrested and, possibly, executed.

By the end of the war, the RSS had decoded around a quarter of a million intercepts. It was very smart of MI5 to realize that it could leverage a large number of trained radio operators both to cover the country with receivers and to free up military stations for other uses.

Meanwhile, on the other side of the Atlantic, the FCC had a similar plan.

The BBC did a documentary about the work the hams did during the war. You can watch it below.

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