Encrypted Deckchairs

by Paul Curzon and Kok Ho Huen, Queen Mary University of London

Lots of stripy deckchairs on a beach in the setting sun
Image by Dean Moriarty from Pixabay  

Summer is here so it is time to start looking for secret messages on the beach. All those stripy deckchairs and windbreaks seem a great place to hide messages.

How might a deckchair contain a message? Well, the Mars Perseverance Rover famously showed how. It encoded “DARE MIGHTY THINGS” along with the GPS coordinates of NASA’s Jet Propulsion Laboratory in its parachute that allowed it to land safely on the surface of Mars. The pattern in the parachute involves a series of rings of orange stripes. Within each ring are groups of 7 stripes. Each group encodes a binary version of a letter: so A is 1 or 0000001. In the pattern this becomes 6 yellow stripes and then an orange one. G, being the 7th letter of the alphabet is encoded as 0000111 or four yellow stripes followed by three orange. Each letter is encoded using the same pattern. In this way, with enough stripes you can spell out any message.

Back to deckchairs, you can code patterns in a similar way in the stripes of a deckchair. One deckchair could have fourteen stripes, say, with a choice from two colours for each stripe. Perhaps thin stripes of a different colour could separate them. That would be enough to encode a pair of characters per deckchair using the NASA code (your initials perhaps). Line up a long row of such deckchairs on the beach and you could spell out a whole message. An alternative would be to use Morse code, with two different coloured stripes for dots and dashes…or invent your own stripy code.

Alternatively, if you have dress making skills, make a stripy dress that really makes a statement.

Sadly, so far, all the deckchairs I’ve tried to decode appear to have only contained gobbledygook though perhaps I’ve just not tried the right code yet, or found the right deckchair. Or maybe, so far no one has actually coded a message in a deckchair. If you have an old deckchair and some sewing skills, perhaps you could be the first and re-skin it with a message.


Steganographic Origami

If making a deckchair is a bit much for you, more simply you could make an origami deckchair, as we (Ho) did and hide a message in your origami. These videos show how he did it (note his are luxury deckchairs):

Making an origami encoded deckchair, Step one.

Making an origami encoded deckchair, Step two.

Making an origami encoded deckchair, Step three.

More on …


This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Back (page) to the drawing board

by Jo Brodie, Queen Mary University of London

Dart in bullseye of dartboard
Image by StockSnap from Pixabay

Here are some more cunning contraptions, with and without a purpose…


More on …

Related Magazines …


This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Tempest Prognosticator: look out, leeches!

by Jo Brodie, Queen Mary University of London

raindrops on a window
Image by Kranich17 from Pixabay

When we leave our homes we might check a weather app to give us predictions from number-crunching computers, to see if we’ll need an umbrella, but in the mid-1800s the appropriately named George Merryweather thought he’d make use of the alleged weather predicting properties of leeches to create a ‘leech barometer’ to measure the weather. His notion relied on the belief that leeches, kept inside small glass bottles, would try and escape when a storm was due (because they might be more sensitive to subtle changes in electrical conditions in the air that we humans would miss). The escaping leeches would trigger a small hammer placed above the bottles which would strike a bell and alert everyone in earshot that a storm might be imminent and also that your living room was about to be overrun with leeches. Not surprisingly it wasn’t very popular, though Merryweather claimed to have great success with it.


More on …

Related Magazines …


This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Quipu: tie a knot in it

by Jo Brodie, Queen Mary University of London

A string with lots of multicoloured strings attached to it, each with knots tied down them
Quipu in the Museo Machu Picchu, Casa Concha, Cusco
Image by Pi3.124 from Wikimedia CC-BY-SA-4.0

Quipu (the Quechua word for ‘knot’) are knotted, and sometimes differently coloured, strings, made from the hair fibres of llamas or alpacas. They were used by people, such as the Incas, living hundreds of years ago in Andean South America. They used the quipu to keep numeric trade or military records. A ‘database’ was formed of several of the strings tied together at one end. Each string stored numbers as different kinds of knots at different positions along the strings, with positions for ones, tens, hundreds, etc. It worked a bit like an abacus, but with much less danger of losing your work if you turn it upside down. The number ‘1’ was represented as a figure-of-eight knot in the ones position and ‘40’ could be indicated by four simple knots in the tens position. Not many quipu survive and even fewer have been decoded, but anthropologists have begun to find evidence that they might contain not just numbers but a written (well, a tactile) form too.


Make your own Quipu

Make your own Quipu decoration or necklace that represents something by tying knots in coloured string or ribbons.

  1. It could keep track of important numbers for you, such as how much pocket money you have at the end of each week, making a new string (or ribbon) for each week, or
  2. Store some sequence of numbers in a sequence of quipu like the 3 times table or the square numbers or the Fibonacci numbers…, or
  3. Invent a code such as A=1, B=2, … and store a message on your Quipu by spelling it out in numbers and so knots.
A Quipu showing 26 or if using a simple number-letter code, Z

To make your Quipu more colourful tie different coloured strings together end to end to make a single Quipu. One colour string then represents ones and the next tied to it represents tens for a single number and so letter (and so on). Use different colours for your next Quipu.


More on …

Related Magazines …


This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Bullseye! The intelligent dart board

by Jo Brodie, Queen Mary University of London

A dart in the bulls eye of a dartboard
Image by StockSnap from Pixabay

Mark Rober, an engineer and YouTuber who worked for NASA, has created a dartboard that jumps in front of your dart to land you the best score. Throw a dart at his board and infra-red motion capture cameras track its path, and, software (and some maths) predicts where it will land. Motors then move the dartboard into a better position to up the score in real time!


More on …

Related Magazines …


This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

The Ultimate (do nothing) machine

by Jo Brodie, Queen Mary University of London

A black box with an on-off switch at ON. The top flips open and a robotivc finger pokes out to push the switch back to OFF.
This ultimate machine is a commercially produced version of Minsky’s idea. Image by Drpixie from Wikimedia CC-BY-SA-4.0

In 1952 computer scientist and playful inventor, Marvin Minsky, designed a machine which did one thing, and one thing only. It switched itself off. It was just a box with a motor, switch and something to flip (toggle) the switch off again after someone turned it on. Science fiction writer Arthur C. Clarke thought there was something ‘unspeakably sinister’ about a machine that exists just to switch itself off and hobbyist makers continue to create their own variations today.


More on …

Related Magazines …


This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Simone Giertz: A pat on the shoulder

The Proud Parent Machine

by Jo Brodie, Queen Mary University of London

A pat on the shoulder In lockdown, during the Covid-19 pandemic, inventor and roboticist Simone Giertz created a coin-operated ‘proud parent machine’ which, for 25 US cents, would pat her on the shoulder and give a few words of encouragement. Putting in a coin sent a signal to a microcontroller that turned a motor on which lowered a 3D-printed arm (to pat her shoulder), then played a pre-recorded audio file telling her how proud of her the automaton was. Making the machine involved skills in woodworking, computer-aided design, mechanics and electronics. She also gave a TED Talk called “Why you should make useless things”.


More on …

Related Magazines …


This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Christopher Strachey and the secret of being a Wizard Debugger

by Paul Curzon, Queen Mary University of London

(from the archive)

Code with BUG cross hairs over one area and rest faded out
Image by Pexels from Pixabay 

Elite computer programmers are often called wizards, and one of the first wizards was Christopher Strachey, who went on to be a pioneer of the development of programming languages. The first program he wrote was an Artificial Intelligence program to play draughts: more complicated (and fun) than the programs others were writing at the time. He was not only renowned as a programmer, but also as being amazingly good at debugging – getting them actually to work. On a visit to Alan Turing in Manchester he was given the chance to get his programs working on the Ferranti Mark I computer there. He did so very quickly working through the night to get them working, and even making one play God Save the King on the hooter. He immediately gained a reputation as being a “perfect” programmer. So what was his secret?

No-one writes complex code right first time, and programming teams spend more time testing programs than writing them in the first place to try and find all the bugs – possibly obscure situations where the program doesn’t do what the person wanted. A big part of the skill of programming is to be able to think logically and so be able to work through what the program actually does do, not just what it should do.

So what was Strachey’s secret that made him so good at debugging? When someone came to him with code that didn’t work, but they couldn’t work out why, he would start by asking them to explain how the program worked to him. As they talked, he would sit back, close his eyes and think about something completely different: a Beethoven symphony perhaps. Was this some secret way to tap his own creativity? Well no. What would happen is as the person explained the program to him they would invariable stop at some point and say something like: “Oh. Wait a minute…” and realise their mistake. By getting them to explain he was making them work through in detail how the program worked. Strachey’s reputation would be enhanced yet again.

There is a lesson here for anyone wishing to be a good programmer. Spending time explaining your program is also a good way to find problems. It is also an important part of learning to program, and ultimately becoming a wizard.


More on …

Related Magazines …


This blog is funded by UKRI, through grant EP/W033615/1.

Sophie Wilson: Where would feeding cows take you?

Chip design that changed the world

by Paul Curzon, Queen Mary University of London

(Updated from the archive)

cows grazing
Image by Christian B. from Pixabay 

Some people’s innovations are so amazing it is hard to know where to start. Sophie Wilson is like that. She helped kick start the original 80’s BBC micro computer craze, then went on to help design the chips in virtually every smartphone ever made. Her more recent innovations are the backbone that is keeping broadband infrastructure going. The amount of money her innovations have made easily runs into tens of billions of dollars, and the companies she helped succeed make hundreds of billions of dollars. It all started with her feeding cows!

While still a student Sophie spent a summer designing a system that could automatically feed cows. It was powered by a microcomputer called the MOS 6502: one of the first really cheap chips. As a result Sophie gained experience in both programming using the 6502’s set of instructions but also embedded computers: the idea that computers can disappear into other everyday objects. After university she quickly got a job as a lead designer at Acorn Computers and extended their version of the BASIC language, adding, for example, a way to name procedures so that it was easier to write large programs by breaking them up into smaller, manageable parts.

Acorn needed a new version of their microcomputer, based on the 6502 processor, to bid for a contract with the BBC for a project to inspire people about the fun of coding. Her boss challenged her to design it and get it working, all in only a week. He also told her someone else in the team had already said they could do it. Taking up the challenge she built the hardware in a few days, soldering while watching the Royal Wedding of Charles and Diana on TV. With a day to go there were still bugs in the software, so she worked through the night debugging. She succeeded and within the week of her taking up the challenge it worked! As a result Acorn won a contract from the BBC, the BBC micro was born and a whole generation were subsequently inspired to code. Many computer scientists, still remember the BBC micro fondly 30 years later.

That would be an amazing lifetime achievement for anyone. Sophie went on to even greater things. Acorn morphed into the company ARM on the back of more of her innovations. Ultimately this was about returning to the idea of embedded computers. The Acorn team realised that embedded computers were the future. As ARM they have done more than anyone to make embedded computing a ubiquitous reality. They set about designing a new chip based on the idea of Reduced Instruction Set Computing (RISC). The trend up to that point was to add ever more complex instructions to the set of programming instructions that computer architectures supported. The result was bloated systems that were hungry for power. The idea behind RISC chips was to do the opposite and design a chip with a small but powerful instruction set. Sophie’s colleague Steve Furber set to work designing the chip’s architecture – essentially the hardware. Sophie herself designed the instructions it had to support – its lowest level programming language. The problem was to come up with the right set of instructions so that each could be executed really, really quickly – getting as much work done in as few clock cycles as possible. Those instructions also had to be versatile enough so that when sequenced together they could do more complicated things quickly too. Other teams from big companies had been struggling to do this well despite all their clout, money and powerful computer mainframes to work on the problem. Sophie did it in her head. She wrote a simulator for it in her BBC BASIC running on the BBC Micro. The resulting architecture and its descendants took over the world, with ARM’s RISC chips running 95% of all smartphones. If you have a smartphone you are probably using an ARM chip. They are also used in game controllers and tablets, drones, televisions, smart cars and homes, smartwatches and fitness trackers. All these applications, and embedded computers generally, need chips that combine speed with low energy needs. That is what RISC delivered allowing the revolution to start.

If you want to thank anyone for your personal mobile devices, not to mention the way our cars, homes, streets and work are now full of helpful gadgets, start by thanking Sophie…and she’s not finished yet!


More on …

Related Magazines …


This blog is funded by UKRI, through grant EP/W033615/1.

The Hive at Kew

Art meets bees, science and electronics

by Paul Curzon, Queen Mary University of London

(from the archive)

a boy lying in the middle of the Hive at Kew Gardens.

Combine an understanding of science, with electronics skills and the creativity of an artist and you can get inspiring, memorable and fascinating experiences. That is what the Hive, an art instillation at Kew Gardens in London, does. It is a massive sculpture linked to a subtle sound and light experience, surrounded by a wildflower meadow, but based on the work of scientists studying bees.

The Hive is a giant aluminium structure that represents a bee hive. Once inside you see it is covered with LED lights that flicker on and off apparently randomly. They aren’t random though, they are controlled by a real bee hive elsewhere in the gardens. Each pulse of a light represents bees communicating in that real hive where the artist Wolfgang Buttress placed accelerometers. These are simple sensors like those in phones or a BBC micro:bit that sense movement. The sensitive ones in the bee hive pick up vibrations caused by bees communicating with each other The signals generated are used to control lights in the sculpture.

A new way to communicate

This is where the science comes in. The work was inspired by Martin Bencsik’s team at Nottingham Trent University who in 2011 discovered a new kind of communication between bees using vibrations. Before bees are about to swarm, where a large part of the colony split off to create a new hive, they make a specific kind of vibration, as they prepare to leave. The scientists discovered this using the set up copied by Wolfgang Buttress, using accelerometers in bee hives to help them understand bee behaviour. Monitoring hives like this could help scientists understand the current decline of bees, not least because large numbers of bees die when they swarm to search for a new nest.

Hear the vibrations through your teeth

Good vibrations

The Kew Hive has one last experience to surprise you. You can hear vibrations too. In the base of the Hive you can listen to the soundtrack through your teeth. Cover your ears and place a small coffee stirrer style stick between your teeth, and put the other end of the stick in to a slot. Suddenly you can hear the sounds of the bees and music. Vibrations are passing down the stick, through your teeth and bones of your jawbone to be picked up in a different way by your ears.

A clever use of simple electronics has taught scientists something new and created an amazing work of art.


More on …

Related Magazines …

cs4fn issue 4 cover
A hoverfly on a leaf

EPSRC supports this blog through research grant EP/W033615/1, and through EP/K040251/2 held by Professor Ursula Martin.