Stretching the bandwidth: How radio waves have changed our world

Receivers in radio sets pick up radio waves bearing songs, news and conversations transmitted by radio stations miles away, translating the electromagnetic energy into sound that greets us in our home or cars. Radio telescopes tap into electromagnetic waves carrying information from light years away. Radio waves are now helping sleep scientists measure how well a subject is resting.

Take a look at ways in which these waves have changed how we engage with our world, and how new technology is changing the world of radio broadcasts too.

Galaxy quest

It could be the length of an average water bottle or the diameter of the planet — every radio wave can tell us something about the universe. They have helped answer questions such as: What is that star made of? Is that a black hole at the centre of a distant galaxy? What kind of mood is the Sun in, and how is that likely to affect our week?

Each astronomical object has a unique magnetic field determined by its composition and the way it interacts with objects around it. This information can be read in the electromagnetic waves that the objects emit, and of course the way those waves change over time. This field of study is called radio astronomy, and is less than a century old.

It was born in 1932, when American physicist Karl Jansky of the Bell Telephone Lab in New Jersey was investigating disruptions to transatlantic telephone communication. The disruptions were being caused by radio waves, perhaps from a storm.

To help him in his investigation, he developed a large directional antenna system that could be rotated on four car tyres that was nicknamed Jansky’s Merry-Go-Round. As he tuned and rotated this antenna over months, he detected storms, yes. But also, a very distant hiss. The hiss was strongest when the antenna was pointed in the direction of the centre of the Milky Way.

That was the scientific world’s first clue that distant astronomical bodies could be “heard” as they moved about. Today, giant radio telescopes with massive antennae — such as the FAST or Five-hundred-metre Aperture Spherical Telescope in China, and India’s Giant Metrewave Radio Telescope in Pune — are used to read the sky.

Moss appeal

Moss, the slimy vegetation that grows on damp surfaces, is being used to power a radio receiver in the UK.

In 2014, Swiss designer Fabienne Felder, along with biochemists Paolo Bombelli and Ross Dennis, all three from the University of Cambridge, tapped into the plant to effectively turn surplus electrons produced during photosynthesis into electrical energy, treating the moss as a biological solar panel. The radio receiver, called Moss FM, is run on a rechargeable battery charged by these moss cells.

The team’s research indicated, for instance, that if 25% of London’s 9 million people charged their mobile phones for two hours every other day with moss, the city would save enough electricity (about 42.5 million kWh) to light up a small town, and reduce its carbon footprint by 39,632 tonnes of carbon dioxide a year.

And all this because moss is a slow creeper. It grows so slowly, that it is less efficient at converting the electrons produced during photosynthesis into sugars, which enables scientists to tap into them. Could succulents be next? Researchers from Israel used some to harvest electrical power in a similar fashion, as part of a study published in the journal ACS Applied Materials & Interfaces in November. Moss isn’t the only one green with the superpower.

Sleep trackers

How well are you sleeping? How often do you toss about in bed? How much of your sleep is light, deep, or REM (rapid eye movement, the deepest stage) sleep?

Radio waves could help researchers answer these questions accurately, for wider sleep studies conducted on people as they sleep in their homes, with none of the disruption caused by sensors applied to the body.

Researchers at the Massachusetts Institute of Technology (MIT) and Massachusetts General Hospital have devised an artificial intelligence (AI)-driven algorithm that analyses radio waves around a person to estimate sleep stages.

The device works on the principle that radio waves reflect off a body and the slightest movement can change the frequency, which can be analysed to infer sleep stages.

In 2017, the researchers were granted a patent for their motion-tracking radio-frequency device, RF-Sleep, which can track sleep while simply sitting in the room, like a wi-fi router. Honestly, what’s next?

AI on the radio

In the US, an AI-driven software program is creating and anchoring radio shows. Ohio-based media company Futuri launched the first AI-driven localised radio content service, RadioGPT, in February.

The system scans news sources and social media sites to curate a list of trending topics pertinent to a local market. It then uses GPT-3 technology to craft a radio script, and turns the script into an audio show using the voices of existing radio jockeys (RJs) or by creating new “voices”. So far, the AI RJs have chatted about traffic and weather, offered updates on national newsbreaks, teased upcoming song releases and even co-hosted shows with up to three AI anchors.

In June, US-based Alpha Media’s KBFF Live 95.5 FM station used RadioGPT to create an AI avatar that sounds like the station’s RJ Ashley Elzinga. The tool is meant to help their existing RJs multitask. So far, AI Ashley has anchored a segment, chatted with a listener, and sounded only a little bit off-key. “Congratulations,” she said to a contest winner, for instance, with no new inflection in her “voice” at all.