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Old 11th Jan 2021, 5:19 pm   #21
Panrock
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Default Re: "Radio Teleswitch" turnoff; April 2023

Something very basic. How is the code impressed on the long wave signal?

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Old 11th Jan 2021, 5:41 pm   #22
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Default Re: "Radio Teleswitch" turnoff; April 2023

Our house in Cambridge has a Radio Teleswitch fitted, which has been switching on at 11.30pm and off at 6.30am GMT ever since I bought the place in 1999. Though the house no longer has electric heating, there's still a contactor there which also changes over the meter reading. The resounding 'clunk' from under the stairs is a signal that it's time to go to bed and I think I'll miss it when it's gone!

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Old 11th Jan 2021, 5:48 pm   #23
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Default Re: "Radio Teleswitch" turnoff; April 2023

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Something very basic. How is the code impressed on the long wave signal?

Steve
I think it is phase modulated, but someone will be able to give a more accurate description. But you can actually hear it. Tune in 198 kHz on an SSB receiver or a receiver with a BFO and you can hear the very slight wobble of a couple of Hz (?) on the carrier if you off tune by a few hundred Hz.

If I remember rightly it started sometime in the early 1980s. I worked at BBC Crowsley Park Technical Receiving Station. The transmission on 198 kHz was not used as our actual frequency standard (we had our own rubidium standard) but its extended accuracy was used to check our equipment.

One day, without warning we noticed this weird wobbling on the 198 carrier. A phone call to Droitwich, and they explained what was going on - with a reprimand from our Engineer In Charge that Crowsley Park should have been informed of this work considering our function!
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Old 11th Jan 2021, 5:58 pm   #24
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Default Re: "Radio Teleswitch" turnoff; April 2023

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Something very basic. How is the code impressed on the long wave signal?

Steve
See http://www.radioteleswitch.org.uk/ - it's phase-modulation of the carrier.

More info here: http://alancordwell.co.uk/Legacy/radio/teleswitch1.html
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Old 11th Jan 2021, 8:57 pm   #25
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Default Re: "Radio Teleswitch" turnoff; April 2023

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If I remember rightly it started sometime in the early 1980s.
It started in 1983 and the slow phase-mod was applied to all 200kHz LF transmitters.
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Old 11th Jan 2021, 9:01 pm   #26
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Default Re: "Radio Teleswitch" turnoff; April 2023

Panrock wrote: "Something very basic. How is the code impressed on the long wave signal?"

Simplified circuit of the Pulse Duration Modulation circuit.

From the EBU Review:
"The parallel AC-coupled pulse duration modulator system (Marconi Pulsam) offered by the contractor for the same transmitters was inherently capable of high-efficiency accompanied by a good quality audio-frequency modulation comparable with most alternative high-level modulation systems."

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Old 11th Jan 2021, 9:03 pm   #27
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Default Re: "Radio Teleswitch" turnoff; April 2023

Here's the BBC paper about it.

http://downloads.bbc.co.uk/rd/pubs/reports/1984-19.pdf
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Old 11th Jan 2021, 9:20 pm   #28
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Default Re: "Radio Teleswitch" turnoff; April 2023

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Panrock wrote: "Something very basic. How is the code impressed on the long wave signal?"

Simplified circuit of the Pulse Duration Modulation circuit.

"The parallel AC-coupled pulse duration modulator system (Marconi Pulsam) offered by the contractor for the same transmitters was inherently capable of high-efficiency accompanied by a good quality audio-frequency modulation comparable with most alternative high-level modulation systems."
That's the transmitter, not the switching signal! Used at Rampisham on HF too. Skelton used PWM but with a single series switching valve. Skelton, incidentally, was the last UK station to use PWM switching valves, the others, Droitwich included, being converted to solid-state modulation. However, I digress...
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Old 11th Jan 2021, 9:26 pm   #29
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Default Re: "Radio Teleswitch" turnoff; April 2023

The article was more concerned how the PDM signals were introduced into the final amplifier stages in the transmitter.
There isn't much in the text about the data system.

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Old 11th Jan 2021, 10:26 pm   #30
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Default Re: "Radio Teleswitch" turnoff; April 2023

Data format: http://alancordwell.co.uk/Legacy/radio/teleswitch2.html
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Old 12th Jan 2021, 1:54 am   #31
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Default Re: "Radio Teleswitch" turnoff; April 2023

Heard an interesting talk about the electricity distribution systems from Peter Grove of General Electric today via Zoom: he said that the old timeswitches, like today's smartmeters, had to be programmed with staggered times to allow reasonable time distribution of the load changes.

He also mentioned that smartmeters send a continuous data stream back to the supply company which is used for your realtime usage display. Not only that, but if there was a power break each smartmeter would send a 'last gasp' message before it shut down, and if the company gets last gasps from all the houses in your street, the maintenance crew will be on their way while you're still trying to work out who to phone. When the supply comes back it sends a 'first breath' message to confirm.
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Old 12th Jan 2021, 7:17 pm   #32
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Default Re: "Radio Teleswitch" turnoff; April 2023

I had no idea that 'off-peak' tariffs were still available.
I thought that the change to electricity for street lighting, plus the abandonment of the trams had seen it off.
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Old 12th Jan 2021, 7:42 pm   #33
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Default Re: "Radio Teleswitch" turnoff; April 2023

"Off peak" - White-meter, Economy-7 etc, was a good idea to provide base-load for power stations [Nuclear, large coalburners] that arent' easily-turn-on-and-offable. With the switch from coal to gas [which can be more load-responsive] the benefits of night-time base-load became less so the dual-tariff approach was disfavoured.

As 'renewables' become more in-the-mix it becomes complicated again; the wind doesn't blow consistently and solar doesn't work at night. Add in overnight charging of electric cars [which could be thought of as the 21st century electricity-demand equivalent of night-storage-heaters] and the logic for some kind of 'smart metering' - ideally on a regional rather than national basis - becomes obvious.

The 'Teleswitch' approach could, in theory, have been expanded to handle this - but there are more-adaptive approaches now available. A Teleswitch can't 'tell' the grid that the solar-panels on your roof are in bright sunlight so you're feeding power into the grid rather than drawing it.
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Old 12th Jan 2021, 8:30 pm   #34
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Default Re: "Radio Teleswitch" turnoff; April 2023

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'...With the switch from coal to gas [which can be more load-responsive] the benefits of night-time base-load became less so the dual-tariff approach was disfavoured.'
I was always told as an apprentice in the 1970s that street-lighting and night-time load were to be encouraged by the generating companies for this very reason: the inability of coal-fired plant to respond to load change.

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'Add in overnight charging of electric cars...'
Evidently plans are afoot - and might actually be in place somewhere - to use electric cars as 'national grid storage facilities' so you can export back to the grid when you car is fully charged, although the two EV owners I know say this facility isn't actually in place yet where they live. Metering will have to cope with that.

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'The 'Teleswitch' approach could, in theory, have been expanded to handle thisA Teleswitch can't 'tell' the grid...'
I seem to remember that when radio data over LF was developed and introduced, it might have other uses than to switch electricity meters, but I can't find anything about this in my scant notes!
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Old 12th Jan 2021, 10:15 pm   #35
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Default Re: "Radio Teleswitch" turnoff; April 2023

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"As 'renewables' become more in-the-mix it becomes complicated again; the wind doesn't blow consistently and solar doesn't work at night. Add in overnight charging of electric cars [which could be thought of as the 21st century electricity-demand equivalent of night-storage-heaters] and the logic for some kind of 'smart metering' - ideally on a regional rather than national basis - becomes obvious.

The 'Teleswitch' approach could, in theory, have been expanded to handle this - but there are more-adaptive approaches.......

The simple 'one way, one to many' radio teleswitching on 198LW is a hugely underused facility with massive potential in the post-fossil-fuel era.

It's current use ranges from sychronisation service for white meter heating clocks at its simplest, to a much more complex system which switches storage heating load on and off according to forecasts for a minority of still-available domestic tariffs.

This means that it gives suppliers the opportunity-on a geographic basis-to shed load according to grid conditions.

Traditional Storage and water heating demand lend themselves to this flexibility, for which the system was designed 30 years ago.

Now we have public policy for electric cars (which double average household load) and public policy to end gas heating (which close to double that again). In other words a potential quadroupling of domestic demand with load which can very easily bear time-shifted switching.

The ability to 'flatten the peak' in daily demand is one which cuts the average consumer cost of bills dramatically. The present trend, as renewable generation cost comes down, is a peak cost per unit which is many times higher than the average wholesale cost of power, a differential which is growing.

The simple truth is that there are now occasions where units not generated (shed load) are more valuable than units generated.

The service was never extensively used beyond the old SSEB/Hydro Board areas (probably due to availability of gas for generation and heating?) . But its simplicity, reliability and the fact that it is a proven system.

A system whose time has perhaps come too late?
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Old 12th Jan 2021, 10:17 pm   #36
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Default Re: "Radio Teleswitch" turnoff; April 2023

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Evidently plans are afoot - and might actually be in place somewhere - to use electric cars as 'national grid storage facilities' so you can export back to the grid when you car is fully charged, although the two EV owners I know say this facility isn't actually in place yet where they live. Metering will have to cope with that.
Yes, this exists, and I'm involved with a project which is testing it out in Milton Keynes at the moment. In principle, the Radio Teleswitch system ought to be useful for it. One of the times it's a good idea to push electricity back in to the grid is when there's a shortage of generation and the price is high (I believe this very evening is supposed to be one of those times). This is a nationwide situation so a broadcast system would be appropriate.

In practice, however, the control of these things tends to be much more localised so that the load and supply on individual substations can be balanced out to avoid overloading bits of infrastructure. All this assumes that meters in people's homes are on-line sending and receiving live data all the time.

Returning to the metering topic, I have as a result of this work seen with my own eyes what happens when the direction of power flow is reversed. With a spinning-disc type meter, the disc does indeed go backwards! I don't know if the digits count down. We didn't leave our unofficial test running long enough to find out...

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Old 12th Jan 2021, 11:07 pm   #37
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Default Re: "Radio Teleswitch" turnoff; April 2023

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'The service was never extensively used beyond the old SSEB/Hydro Board areas...'
I had radio teleswitching in Cumbria (DNO at the time being NORWEB). Got it disconnected and the storage heaters removed when I had oil central heating fitted.
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Old 12th Jan 2021, 11:26 pm   #38
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Default Re: "Radio Teleswitch" turnoff; April 2023

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.....

Returning to the metering topic, I have as a result of this work seen with my own eyes what happens when the direction of power flow is reversed. With a spinning-disc type meter, the disc does indeed go backwards! I don't know if the digits count down. We didn't leave our unofficial test running long enough to find out...

Chris
Indeed they do..... my first solar PV system was installed on an old spinning disc meter system around November. The electricity supplier changed the meter about six months later having had a summer meter reading that was lower than the spring one. And sent me a new (estimated) higher bill for the period in question.
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Old 13th Jan 2021, 10:01 am   #39
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Default Re: "Radio Teleswitch" turnoff; April 2023

As the original subject has now been explored and clarified this thread is being closed.
We will await future developments that are clearly going to be required to be agile enough for an electric future.

Cheers

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