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Monitor space weather by tuning into signals sent to submarines

Monitoring space weather takes no more than a coil antenna, a suitable external “sound card,” and a laptop computer. Place the antenna farther from the laptop than is shown here to avoid electromagnetic interference.

In the 1960s and ’70s, musicians would sometimes insert into their releases odd sounds that could be made intelligible only by rotating the vinyl record backward using your finger. If you suspect this is only an urban legend, load a digital version of Electric Light Orchestra’s 1975 recording of “Fire on High” into an audio editor like Audacity and play it in reverse. You’ll hear ELO drummer Bev Bevan very clearly say, “The music is reversible, but time...turn back, turn back, turn back.”

In the 1980s, vinyl records gave way to compact discs, which weren’t amenable to such “ backmasking.” But at least one CD of that era contains a hidden message: Virgin Records’ 1983 release of the album Tubular Bells, recorded a decade earlier at Richard Branson’s Manor Studio in Shipton-on-Cherwell, England.

You see, an hour’s drive north from Shipton is a suburb of Rugby called Hillmorton, where at the time the British government operated a very-low-frequency (VLF) radio station to send messages to submarines. It seems the powerful emanations from this nearby station, broadcast at a radio frequency of just 16 kilohertz (within the audio range), were picked up by the electronic equipment at Branson’s studio and recorded at a level too low for anyone to notice.

After learning of this, I purchased an old CD of Tubular Bells, ripped a WAV file of one track, and piped it into a software-defined-radio package. Tuning to 16 kHz and setting the SDR software to demodulate continuous-wave signals immediately revealed Morse code. I couldn’t copy much of it, but I could make out many repetitions of VVV (“testing”) and GBR (the station’s call sign).

This inadvertent recording aptly demonstrates that VLF transmissions aren’t at all hard to pick up. And these signals can reveal more than just the presence of a powerful radio transmitter nearby. The application I had in mind was to use changes in VLF-signal strength to monitor space weather.

The solar-flare monitor consists of a coil antenna and external “sound card,” which connects to a laptop computer. Tuning the coil antenna to an appropriate frequency also required a signal generator, a protoboard, and an oscilloscope. James Provost

That’s possible because these VLF transmissions travel over large distances inside the globe-encircling waveguide that is formed by the Earth’s surface and the ionosphere. Solar flares—and rare astronomical events called gamma-ray bursts—can alter the ionosphere enough to change how radio signals propagate in this waveguide. I hoped to use VLF broadcasts to track such goings-on.

There’s a long history of amateur astronomers using VLF radio equipment to measure solar flares by the sudden ionospheric disturbances (SIDs) they spawn. Years ago, it was a challenge to build suitable gear for these observations, but it now takes just a few modest Amazon purchases and a laptop computer.

The first item needed is a simple coil antenna. The model I bought (US $35) actually contains two coils. One was connected to a variable capacitor, so it can be tuned to various AM-broadcast frequencies; the other coil, of just two turns and inductively coupled to the first one, was wired to the output jack. I bypassed that two-turn coil and wired the jack directly to the wider coil, adding a couple of capacitors in parallel across it to lower its resonant frequency to 25 kHz.

There’s a long history of amateur astronomers using VLF radio to measure solar flares by the ionospheric disturbances they spawn.

To choose the right capacitors, I purchased a $9 signal generator, also on Amazon, temporarily connected that wider coil in series with a 1,000-ohm resistor, and applied a sinusoidal signal to this circuit. I used an oscilloscope to identify the frequency that caused the alternating voltage across the coil to peak. With some experimentation, I was able to find a couple of ceramic capacitors (nominally 0.11 microfarads in total) to place in parallel with the coil to set the resonant frequency near the broadcast frequency of some U.S. Navy VLF transmitters.

Using a scrounged 3.5-mm plug, I then plugged the modified coil antenna into the mic input of an external “sound card,” having purchased one for $34 on Amazon that allowed a sampling rate of 96 kHz. This feature was key, because my plan was to tune into a station that the U.S. Navy operates in Cutler, Maine, which goes by the call sign NAA and broadcasts at 24 kHz. Fans of Harry Nyquist will remember that you need to sample a signal at least two times per cycle to capture it properly. So a typical sound card that samples at 44 kHz wouldn’t cut it.

The final thing I needed was suitable software. I experimented with two SDR packages ( HDSDR and SDR Sharp), with my sound card taking the place of the usual radio dongle. While these packages displayed transmissions from NAA clearly enough, they didn’t provide a good way to monitor variations in signal strength over time. But I soon discovered how to do that with Spectrum Lab, following an online tutorial explaining how to use this software to measure SIDs.

Within days of its construction, the monitor registered the signal from a solar flare . Two flares earlier that day, which were well documented in X-ray measurements taken by NASA’s GOES-16 satellite in geosynchronous orbit [purple line], did not affect the VLF measurements [magenta line] because they occurred when the relevant part of the ionosphere was in darkness and shielded from the sun. James Provost

This combination of desktop AM antenna, external sound card, and Spectrum Lab software proved ideal. With it, I am not only able to monitor NAA, located about 1,400 kilometers from my home in North Carolina, I can also pick up the VLF station in LaMoure, N.D. (call sign NML), which transmits on 25.2 kHz. At times, I clearly receive the Jim Creek Naval station (NLK), near Oso, Wash., on 24.8 kHz and can even register the Navy’s Aguada station in Puerto Rico, despite it transmitting at 40.75 kHz, far from my coil’s resonant frequency.

The first few days of using this gear captured the expected pattern of daily variation in the signal from NAA, with sharp transitions when the sun rises and sets. Within a week, the sun became unusually active, producing three good-size flares in one day—as documented by NASA’s Geostationary Operational Environmental Satellites, which measure X-ray flux in geosynchronous orbit. Two of those flares occurred when the East Coast was in darkness, so they had no effect on the relevant portion of the ionosphere or the signal strength I was monitoring. But the third, which took place at about 11 a.m. local time, showed up nicely.

It’s rather amazing that with just $70 worth of simple electronics and a decade-old laptop, I can now monitor flares on the surface of the sun. One day I might see the effects of a gamma-ray burst taking place on a star in a distant galaxy, as a group at Stanford did in 2004. I’ll probably have to wait years to detect one of those, though. In the meantime, I can entertain myself hunting for more radio signals inadvertently recorded at the Manor Studio in the ’70s. Maybe I’ll start those explorations, fittingly, with Van Morrison’s 1978 album Wavelength.

This article appears in the February 2021 print issue as “A Barometer for Space Weather.”

David Schneider is a senior editor at IEEE Spectrum. His beat focuses on computing, and he contributes frequently to Spectrum's Hands On column. He holds a bachelor's degree in geology from Yale, a master's in engineering from UC Berkeley, and a doctorate in geology from Columbia.

The Nest founder tells of years in pursuit of a thermostat he actually likes

Tony Fadell shows off the Nest thermostat in 2012.

The thermostat chased me for 10 years.

That is pretty extreme, by the way. If you’ve got an idea for a business or a new product, you usually don’t have to wait a decade to make sure it’s worth doing.

For most of the 10 years that I idly thought about thermostats, I had no intention of building one. It was the early 2000s, and I was at Apple making the first iPhone. I got married, had kids. I was busy.

But then again, I was also really cold. Bone-chillingly cold.

Every time my wife and I drove up to our Lake Tahoe ski cabin on Friday nights after work, we’d have to keep our snow jackets on until the next day. The house took all night to heat up.

Adapted from the book BUILD: An Unorthodox Guide to Making Things Worth Making by Tony Fadell. Copyright 2022 by Tony Fadell. Reprinted by permission of Harper Business, an imprint of HarperCollins Publishers.

Walking into that frigid house drove me nuts. It was mind-boggling that there wasn’t a way to warm it up before we got there. I spent dozens of hours and thousands of dollars trying to hack security and computer equipment tied to an analog phone so I could fire up the thermostat remotely. Half my vacations were spent elbow-deep in wiring, electronics littering the floor. But nothing worked. So the first night of every trip was always the same: We’d huddle on the ice block of a bed, under the freezing sheets, watching our breath turn into fog until the house finally warmed up by morning.

Then on Monday I’d go back to Apple and work on the first iPhone. Eventually I realized I was making a perfect remote control for a thermostat. If I could just connect the HVAC system to my iPhone, I could control it from anywhere. But the technology that I needed to make it happen—reliable low-cost communications, cheap screens and processors—didn’t exist yet.

How did these ugly, piece-of-crap thermostats cost almost as much as Apple’s most cutting-edge technology?

A year later we decided to build a new, superefficient house in Tahoe. During the day I’d work on the iPhone, then I’d come home and pore over specs for our house, choosing finishes and materials and solar panels and, eventually, tackling the HVAC system. And once again, the thermostat came to haunt me. All the top-of-the-line thermostats were hideous beige boxes with bizarrely confusing user interfaces. None of them saved energy. None could be controlled remotely. And they cost around US $400. The iPhone, meanwhile, was selling for $499.

How did these ugly, piece-of-crap thermostats cost almost as much as Apple’s most cutting-edge technology?

The architects and engineers on the Tahoe project heard me complaining over and over about how insane it was. I told them, “One day, I’m going to fix this—mark my words!” They all rolled their eyes—there goes Tony complaining again!

At first they were just idle words born of frustration. But then things started to change. The success of the iPhone drove down costs for the sophisticated components I couldn’t get my hands on earlier. Suddenly high-quality connectors and screens and processors were being manufactured by the millions, cheaply, and could be repurposed for other technology.

My life was changing, too. I quit Apple and began traveling the world with my family. A startup was not the plan. The plan was a break. A long one.

We traveled all over the globe and worked hard not to think about work. But no matter where we went, we could not escape one thing: the goddamn thermostat. The infuriating, inaccurate, energy-hogging, thoughtlessly stupid, impossible-to-program, always-too-hot-or-too-cold-in-some-part-of-the-house thermostat.

Someone needed to fix it. And eventually I realized that someone was going to be me.

This 2010 prototype of the Nest thermostat wasn’t pretty. But making the thermometer beautiful would be the easy part. The circuit board diagrams point to the next step—making it round.Tom Crabtree

The big companies weren’t going to do it. Honeywell and the other white-box competitors hadn’t truly innovated in 30 years. It was a dead, unloved market with less than $1 billion in total annual sales in the United States.

The only thing missing was the will to take the plunge. I wasn’t ready to carry another startup on my back. Not then. Not alone.

Then, magically, Matt Rogers, who’d been one of the first interns on the iPod project, reached out to me. He was a real partner who could share the load. So I let the idea catch me. I came back to Silicon Valley and got to work. I researched the technology, then the opportunity, the business, the competition, the people, the financing, the history.

Making it beautiful wasn’t going to be hard. Gorgeous hardware, an intuitive interface—that we could do. We’d honed those skills at Apple. But to make this product successful—and meaningful—we needed to solve two big problems:

It needed to save energy.

And we needed to sell it.

In North America and Europe, thermostats control half a home’s energy bill—something like $2,500 a year. Every previous attempt to reduce that number—by thermostat manufacturers, by energy companies, by government bodies—had failed miserably for a host of different reasons. We had to do it for real, while keeping it dead simple for customers.

Then we needed to sell it. Almost all thermostats at that point were sold and installed by professional HVAC technicians. We were never going to break into that old boys’ club. We had to find a way into people’s minds first, then their homes. And we had to make our thermostat so easy to install that literally anyone could do it themselves.

It took around 9 to 12 months of making prototypes and interactive models, building bits of software, talking to users and experts, and testing it with friends before Matt and I decided to pitch investors.

Once we had prototypes of the thermostat, we sent it out to real people to test.

It was fatter than we wanted. The screen wasn’t quite what I imagined. Kind of like the first iPod, actually. But it worked. It connected to your phone. It learned what temperatures you liked. It turned itself down when nobody was home. It saved energy. We knew self-installation was potentially a huge stumbling block, so everyone waited with bated breath to see how it went. Did people shock themselves? Start a fire? Abandon the project halfway through because it was too complicated? Soon our testers reported in: Installation went fine. People loved it. But it took about an hour to install. Crap. An hour was way too long. This needed to be an easy DIY project, a quick upgrade.

So we dug into the reports—what was taking so long? What were we missing?

Our testers...spent the first 30 minutes looking for tools.

Turns out we weren’t missing anything—but our testers were. They spent the first 30 minutes looking for tools—the wire stripper, the flathead screwdriver; no, wait, we need a Phillips. Where did I put that?

Once they gathered everything they needed, the rest of the installation flew by. Twenty, 30 minutes tops.

I suspect most companies would have sighed with relief. The actual installation took 20 minutes, so that’s what they’d tell customers. Great. Problem solved.

But this was going to be the first moment people interacted with our device. Their first experience of Nest. They were buying a $249 thermostat—they were expecting a different kind of experience. And we needed to exceed their expectations. Every minute from opening the box to reading the instructions to getting it on their wall to turning on the heat for the first time had to be incredibly smooth. A buttery, warm, joyful experience.

And we knew Beth. Beth was one of two potential customers we defined. The other customer was into technology, loved his iPhone, was always looking for cool new gadgets. Beth was the decider—she dictated what made it into the house and what got returned. She loved beautiful things, too, but was skeptical of supernew, untested technology. Searching for a screwdriver in the kitchen drawer and then the toolbox in the garage would not make her feel warm and buttery. She would be rolling her eyes. She would be frustrated and annoyed.

Shipping the Nest thermostat with a screwdriver "turned a moment of frustration into a moment of delight"Dwight Eschliman

So we changed the prototype. Not the thermostat prototype—the installation prototype. We added one new element: a little screwdriver. It had four different head options, and it fit in the palm of your hand. It was sleek and cute. Most importantly, it was unbelievably handy.

So now, instead of rummaging through toolboxes and cupboards, trying to find the right tool to pry their old thermostat off the wall, customers simply reached into the Nest box and took out exactly what they needed. It turned a moment of frustration into a moment of delight.

Sony laughed at the iPod. Nokia laughed at the iPhone. Honeywell laughed at the Nest Learning Thermostat.

In the stages of grief, this is what we call Denial.

But soon, as your disruptive product, process, or business model begins to gain steam with customers, your competitors will start to get worried. And when they realize you might steal their market share, they’ll get pissed. Really pissed. When people hit the Anger stage of grief, they lash out, they undercut your pricing, try to embarrass you with advertising, use negative press to undermine you, put in new agreements with sales channels to lock you out of the market.

And they might sue you.

The good news is that a lawsuit means you’ve officially arrived. We had a party the day Honeywell sued Nest. We were thrilled. That ridiculous lawsuit meant we were a real threat and they knew it. So we brought out the champagne. That’s right, f---ers. We’re coming for your lunch.

With every generation, the product became sleeker, slimmer, and less expensive to build. In 2014, Google bought Nest for $3.2 billion. In 2016 Google decided to sell Nest, so I left the company. Months after I left, Google changed its mind. Today, Google Nest is alive and well, and they’re still making new products, creating new experiences, delivering on their version of our vision. I deeply, genuinely, wish them well.