[retrotecchie]

@meldrewreborn

The 198kHz carrier frequency is amplitude modulated by audio to generate the Radio 4 broadcast. However, the carrier has a digital code superimposed on it by modulating the phase of the carrier. Phase Shift Keying. Inaudible to the normal AM reception, but easily allows the digital data to be recovered by RTS equipment.

All users of the system have their own unique codes which are used in each digital message. Meters, time switches, pumping stations, sluicegates, flood warning sirens (and air raid sirens up until 1995) and anything else that uses RTS will only respond to their designated codes.

Here's the blurb from UK Energy Networks :

The system basically comprises user terminals and modems, the central teleswitch control unit (CTCU) the LF Data System, the 198kHz BBC Radio Four transmission system and radio teleswitching receiver controllers (RCs).
Each user of the system, the electricity distribution networks operators and electricity transmission network operator has a unique set of codes enabling them to address only their own block of meters and switches.
These instructions are sent by the network operators to the Central Teleswitch Control Unit (CTCU) housed and maintained by Cygnet Solutions.
The CTCU processes and forwards their switching codes to the BBC Message Assembler at Crystal Palace.
Here, the electricity industry codes are combined with the instructions from other users of the service and sent to the three national networks of transmitters. The main transmitter at Droitwich (see also the BBC site), rated at 500kW, can reach most parts of the UK and some parts of continental Europe while the two smaller transmitters located at Westerglen and Burghead cover Scotland and Northern Ireland.
Messages are encoded onto the Amplitude Modulated (AM) Radio 4 signal using Phase Shift Keying (PSK) techniques.
30 messages are transmitted per minute, each message having 50 bits of data. 18 of these bits are taken up by a BBC header and Cyclic Redundancy Check (CRC) tail. 32 bits are available for data.
The RadioTeleswitch specification (BS7647) lays down specific formats for its user message contents. Two message types are defined:

• command (or immediate) which has priority of broadcast, and on receipt immediately sets a Teleswitch (RCs) internal switches to required status, overriding any programmed status;
• programme, which updates or refreshes the operating program stored within a Teleswitch (i.e. internal switches will not change status until required by the program).

An ‘immediate’ instruction can take one or two minutes from initiation of a request at the terminal of a user, depending on other traffic on the data system, and is intended to allow fast, broadcast load shedding.
The system’s ability to offer users both programmed and immediate broadcast control have enabled companies using the system to provide weather-related control of electricity storage heaters in specialised arrangements such as ‘budget warmth’ and ‘heat with rent’ schemes.


The transmission of cost reflective messages and weather forecast information has allowed the concept of controlled consumption to be extended to provide more comprehensive forms of premium heating and other services. The ability to influence demand patterns more finely so that they respond more immediately to changes in supply cost, is to the advantage of both suppliers and customers. It gives customers another form of choice.

Anyway, for those in the know (and subject to the OSA), abandoning RTS will have consequences and repercussions which go far beyond the energy sector. It rather worries me, to be honest.

[meldrewreborn]

@retrotecchie

Well I did ask. 🤔🤔

[retrotecchie]

@meldrewreborn

Here is a little bit of information for non technical folk to explain what RTS does at the consumer end, and why RTS exists in the first place.

RTS is a system primarily used to control heating systems in all-electric domestic and commercial properties.

Although many folk with existing RTS systems will likely be on an Economy 7 tariff, RTS and E7 are two very different things. RTS works perfectly on a single rate tariff, and Economy 7 doesn't need RTS.

RTS would usually be installed in premises with 'complex' electrical heating installations. That is to say, older legacy systems with night storage heaters and electrically heated hot water. Thanks to the availability of a large amount of cheap overnight electricity when Britain still had a fleet of 26 operational Magnox nuclear reactors, off-peak electricity was so cheap it couldn't be given away.

Complex tariffs such as Heatsave or Flexheat didn't have two rates like E7 or E10, but often had four rates - some even had six or more! As well as the usual peak and off-peak general electricity rates, there were usually two 'heating rates' - day and night and sometimes an additional rate or two for the weekends/holidays.

Many RTS systems even had two electricity meters. The 'white meter' which recorded the normal two rates as per Economy 7 and the 'black meter' which recorded the peak and off-peak heating usage.

But simple time switches or meters were rather inflexible. In order to tweak any parameters on any given installation, an engineer had to physically visit the site and make changes manually. Expensive, and not very responsive so this is where RTS comes in.

Regional electricity boards (back in the day) knew how much available capacity was sloshing around in the networks, and also knew what the weather was doing in their areas, so RTS was like a 'remote' control for these heating systems. If the weather was particularly cold and there was excess electricity that needed dumping, RTS could remotely extend heating periods for customers. If the weather was much warmer or demand on the grid was higher than usual, some heating loads could be switched off remotely.

With many of the compex tariffs, customers wouldn't actually be paying specifically for electricity used for heating on a 'per unit basis', but the heating was rolled into the bundle, controlled by the electricity board with the timings based on grid demand/availabilty and weather conditions.

One way radio control, so to speak, at a regional level.

It also had the advantage than in the event of a failure of a generation asset such as a coal, oil or gas-fired generator dropping off line or being closed for maintenance, heating loads could be shed to reduce demand on the grid at times of power scarcity. People wouldn't just have a power cut. The lights and power would stay on, but instead of every customer having their storage heaters or water tanks all using power at the same time, RTS could juggle the loads around to different times in different areas, thus reducing peak load at any one time.

A very clever system and, in it's time, very effective.

But, we no longer have all that plentiful Magnox power, energy companies no longer offer complex tariffs (except to a few industrial sectors) and the BBC can't keep Droitwich running forever. So that is why it is being shut down.

Of course, one of the downsides of RTS which has been addressed by smart metering (kinda sorta...) is two way communication. Not only the ability to control heating and provide load balancing, but the ability to remotely read the meters.

More modern smart meters are technically capable of providing all the benefits of RTS. I say technically capable...but although meters fitted with Auxiliary Relay Contacts (ALC), otherwise known as 5 or 6 terminal meters are capable of load shedding, this doesn't seem to be something that the energy suppliers are actively invested in...yet.

So, smart meters are the modern equivalent of RTS and in theory should be able to not only provide all the functionality (and more) of RTS, but 'phone home' to the supplier to make billing and meter reading easier....when the communications work!

The 2.8 million RTS systems still out there in the wild will need to be replaced. It's as simple as that. Fortunately, they are split across multiple suppliers and tend to be predominantly in four geographical regions (Scotland, South Coast, North Wales and South West England). Essentially, in locations that had a Magnox power station in near proximity. Other locations may have them in commercial and industrial premises but for domestic users, they are most likely to have been deployed in areas covered by Southern Electricity, Scottish Electricity, Manweb and Norweb.

[meldrewreborn]

@retrotecchie

Thanks for that.

OFGEM recently reckoned 800,000 customers are affected by the switch off. All of those customers will need a smart meter to continue to benefit from their current tariff. Just to put it into context, in Q2 2024, 367,000 electricity smart meters were installed nationally, so the RTS change will prove challenging.

Almost certainly their will be customer reluctance to switch to a smart meter given their reputation, whether that's justified or not. But changing that many meters is a huge task and my advice to anyone affected is to sign up for their smart meter replacement meter ASAP. Later, installers will likely not be able to cope with the volume of work.

[retrotecchie]

@meldrewreborn

I think OFGEM;s figure is for domestic customers who still have RTS-controlled complex heating setups. I once had a tour of the electrical plant at the food factory I worked at a few years ago. One of my mates was in engineering and knew I was an engineer so he gave me a look-round after hours one evening. All RTS and more than one meter as the plant had three separate supplies for different areas of the factory. Domestic RTS is funky enough, but three-phase megawatt-hour systems are proper hairy!

The last time I lived in a property with RTS was an all-electric property I lived in in Hampshire in the mid 90s. Built in 1994, so they were still installing RTS in Southern's patch as late as then!

[meldrewreborn]

@retrotecchie

Well it is domestic customers the forum is primarily aimed at? ? Yes ?

[retrotecchie]

@meldrewreborn

Absolutely, but RTS applies equally, if not more so, to commercial customers. The OFGEM figures for rollout of smart meters includes both domestic and commercial installations.

But still a lot of legacy meters to replace in seven months, even if you just factor the domestic users.

[Molls]

@LeighH_EONNext
What is being done to support those of us in the 'North' who are experiencing signal to Smart Meter issues. My EV and ASHP are too expensive to run on daytime Tariffs

[LeighH_EONNext]

Hey @Molls

Great question. 👍

We do have a solution called a flying lead which is basically an extension from the meter to the comms hub so we can install it up higher to improve the signal.
We are also working on another solution to replace any RTS meter with no signal so if the flying lead doesn't work then we will install a working E7 meter so you can still benefit from having the day and night tariffs available for you. 😊

Thanks Leigh 💟

[Molls]

@LeighH_EONNext
How do I get the flying lead but better still the E7 meter?

Thanks