[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. 🤔🤔

[meldrewreborn]

I wonder if the decision to switch off the RTS signal was predicated on the presumption that smart metering would be so widespread by now that RTS would support comparatively few customers. But of course smart metering has never achieved any of its objectives, so now the basis of the decision is flawed, but nonetheless the steamroller of authority continues, because that’s easier than admitting the truth.

Just wondering on this crisp sunny day.

[retrotecchie]

@meldrewreborn

The BBC are trying to cut costs and Long Wave broadcasting is power-hungry and not cheap.

The current Droitwich transmitters run at 500kW and the transmitter output stages uses a matched pair of high power water cooled valves. These need to be replaced in pairs every couple of years and they only have four 'spares' left. They can be made to order but run in at about £20,000 each.

Radio 4 have already retired two shipping forecasts, the Test Cricket coverage and several other programmes from Long Wave. With internet radio, DAB and digital services, the BBC no longer think the cost of maintaining the Long Wave service is justifiable.

However, the transmitters are owned and operated by Arqiva, and it would be very cheap to just provide the RTS data service on the transmitter at a fraction of the power. 50kW would be ample, and at a tenth of the power, smaller cheaper valves can be used which will last much longer or they could move to a modern 'solid state' low power transmitter.

But the other thing about Radio 4 Long Wave...it's part of our national security! Not only would it still work if the internet went down or there was a major crisis (Droitwich has it's own generators and the control room and transmitter are hardened against EMP or other situations) but Britain's CDAS uses Radio 4 as a marker for the situation 'up top'. Should other communications fail (ELF, for instance) then the commanders at sea have one other method for seeing if we're still here. If they can't get 'The Archers' on Long Wave, they can assume it's all gone a bit pear-shaped and can then open the safe and read the LOLR.

The powers that be obviously think that this doesn't matter...but if the brown and steamy ever hit the fan...☹️