WEBVTT

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So somebody left a comment on the TWP Facebook

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page this week and I had to admit in public that

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I had no idea what they were talking about. The

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comment was about radio carrying a hidden data

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signal and the commenter mentioned a system called

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RTS that I had never heard of. I had to go look

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it up. I've You know, I've been doing broadcast

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engineering my whole career, but I've only ever

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worked in U S radio and this is a UK system.

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So if you're listening from the UK and this all

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sounds like old news to you, I get it. This is

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me doing my homework in public. This is the Tyler

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Woodward project and today I'm talking about

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a system that has been running invisibly inside

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of a radio broadcast since the 1980s Controlling

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hundreds of thousands of people's homes, you

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know, they're home heating overnight and I'm

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covering it now because The BBC just confirmed

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a shutdown date of June 27th 2026 about five

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weeks from now. Opinions are my own and if I

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get something wrong about how things work over

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there, please leave a comment because that's

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apparently how I learn things now. The system

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is called the Radio Teleswitch Service, RTS.

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It's British. And the basic idea is exactly what

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it sounds like. It uses a radio signal to flip

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a switch. Here's the backstory. In the early

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1980s, the UK had a popular electricity deal

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called economy seven. You get cheaper rates overnight

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and people would run their storage heaters and

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hot water on the cheaper nighttime rate. Then

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coast through the day on the heat they'd built

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up. Good deal if you could get it. The problem

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is you need something to tell your electricity

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meter when the cheap hours start and stop. The

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old answer was a mechanical timer, which works

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until you want to change the schedule or adjust

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it seasonally. or respond to what's actually

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happening on the grid that night. Mechanical

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timers don't care about any of that, they just

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tick along. So, someone at the BBC in the energy

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industry figured out they could encode a control

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signal inside an existing radio broadcast. The

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BBC had been running a powerful long -wave transmitter

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in the English Midlands since 1934. It covers

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the whole country. It's already paid for, and

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it's been reliable for 50 -some odd years. Why

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build new infrastructure when you can piggyback

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on something that's already there? I should say,

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just for context, that longwave broadcasting

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isn't really a thing in the US, we don't have

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it. So when I'm talking about BBC Radio 4 running

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on longwave, that's a different part of the radio

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spectrum than what we Americans think of as AM

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radio. Same general idea, just... lower frequencies,

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which means the signal travels much further.

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One transmitter covering an entire country is

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actually pretty realistic at those wavelengths.

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The clever part is that the data signal was invisible.

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The radio broadcast kept running exactly as normal.

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Listeners heard radio 4. Same as always but hidden

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inside the signal there was a very slow stream

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of data being transmitted not audio data control

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data instructions Little boxes mounted next to

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the Electrical meter all across the UK were listening

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for those instructions when the signal said cheap

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rate The box switched the meter. When it said

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back to normal, it switched back. The household

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never touched anything. The utility never had

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to call anybody. It just happened automatically

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every night controlled by a radio station. The

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BBC tested it carefully to make sure it didn't

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affect the actual audio in any way. And it didn't.

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Nobody listening to radio ever knew the signal

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was there. If you want a rough analogy for what

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this kind of thing feels like, think about DTMF

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tones. Those are the tones your phone makes when

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you press a number, you know, old school touch

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tone phones, not cell phones. That's just data

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too. It's just audible. You can hear it happening.

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The RTS signal was the invisible version of that,

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if you will. Closer to how old dial -up modems

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or pager networks sent data. Encoded in a way

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that blends into the signal rather than sitting

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on top of it. The difference with RTS from what

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I could find is it was doing that inside of a

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live national radio broadcast for 40 years without

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anyone ever noticing. They won a major technology

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award for it in 1987, which makes sense. It's

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a elegant solution to a real problem. pretty

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awesome, and it cost almost nothing to build

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because most of the infrastructure, it already

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existed. So the obvious question, at least for

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me, was, do we have anything like this in the

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US? And from what I found, we got there a little

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differently. American utilities have been working

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on the same basic problem for decades. How do

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you manage demand? Well, how do you get people

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to use less electricity during peak hours without

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just raising prices and hoping for the best?

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Their early approach here in the states was called

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AMR, automated meter reading, which is exactly

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what it sounds like. A utility truck drives down

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your street, a radio signal pings your meter,

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and the meter reports back your overall usage.

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It was only one way. The meter talked to the

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truck. The truck, it didn't talk back. That evolved

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into what we now call AMI. Advanced Metering

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Infrastructure. Smart meters. Two -way communication.

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The utility can read your meter. but it can also

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send commands over to it. That's how things like

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time of use pricing works over here. Where your

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rate is cheaper at 2 a .m. than it is at 6 p

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.m., the meter knows what time it is and charges

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you accordingly. No radio broadcast involved

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with that one. No hidden data signal, just cell

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or mesh radio networks talking. directly to each

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other. The difference is the approach. The UK

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built one giant ass transmitter piggybacked a

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control signal onto a national radio broadcast

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and managed hundreds of thousands of electrical

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meters all at the same time simultaneously with

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a single broadcast one signal that went out no

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signal back very simple very cheap The US built

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individual two -way communication systems, but

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at scale every meter is its own node more complex

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more expensive to roll out and more things to

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go wrong, but also more flexible and guess a

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little more precise. Neither one is really any

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better than the other. They were solving the

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same problem with different tools and different

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infrastructures on hand. The BBC happened to

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have a 500 kilowatt transmitter that had been

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running since 1934. American utilities had a

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fragmented privately owned grid with no equivalent

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centralized radio broadcast to borrow from. So

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we built something new. They used what was already

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there. The system has been running for over 40

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years and it's finally shutting down. The transmitter

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itself is old equipment that runs on old components

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that aren't made anymore. When something breaks,

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you find a spare. Eventually you run out of spares.

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They're there at this point. The plan was to

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shut it all down back in June of last year. That

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didn't happen. It turned out hundreds of thousands

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of households in the UK still had the old meters

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running. That depended on the radio signal. The

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smart meter replacements which use cell networks

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instead of radio weren't going out fast enough

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Scotland was especially behind partly because

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of You know a lot of those homes are in remote

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areas where getting someone out to swap a meter

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is a little bit bigger of a lift The shutdown

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date got pushed back once then again Two weeks

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ago, the BBC finally put out a hard date on it.

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June 27th, 2026. This year. And I'm just now

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learning about this. There's one more detail

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here that I thought was really interesting. There's

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actually a rule that says the transmitter can't

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just run the hidden data signal by itself with

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no radio programming. Attached to it. So the

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broadcast has to be there, too So when radio

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4 goes off longwave the control signal has to

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go with it They're the same thing The news story

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about radio 4's shutdown in the energy story

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about the meter system shutting down or not really

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two separate events. It's all one one switch

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off I didn't know any of this until A Facebook

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comment taught me. Finally, something good came

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out of Facebook instead of the other garbage

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I typically get on there. This was cool. I learned

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something from somebody just commenting about

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my last video about AM not having RDS. They're

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like, Hey, over here, we do this. There's a lot

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of infrastructure out there like this systems

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that do real unglamorous important work invisibly

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for decades inside something else people think

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they already understood a Radio station that's

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been switching people's heating on and off every

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night since before some of those people were

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probably ever born Nobody was taught about it.

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It just ran Now it's stopping mostly because

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the hardware finally get too old to fix I Don't

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know how many other things like this are out

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there, but probably more than We'd expect This

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is the Tyler woodward project links in the show

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notes listen at Tyler woodward .me slash podcast

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Make sure you also subscribe Tyler woodward .me

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slash subscribe you can Find me on Instagram,

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blueskyandthreads at tylerwoodward .me and subscribe,

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like the show, leave a rating and review if you

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feel so inclined at Apple podcast and Spotify

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especially. I'll catch you next week.