"whisky-dave" wrote in message
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On Monday, 16 March 2015 18:10:11 UTC, john james wrote:
"whisky-dave" wrote in message
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On Friday, 13 March 2015 18:03:47 UTC, john james wrote:
"whisky-dave" wrote in message
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On Thursday, 12 March 2015 22:48:44 UTC, john james wrote:
"Capitol" wrote in message
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john james wrote:

It is possible with just one TV but not with two.

I would phrase that as "may" be possible, but very unlikely.

It would be easy enough with just one as long as the TV
is showing a broadcast channel and has a backlight that
changes with what is on the screen.

But how will you measure the backlight current ?

From the change in the total house current.

So if I swtich on a 2kw heater then how does that indicate the current
change in the backligh of a TV ?

Its obvious that that heater has been
turned on from the change in the current.

How do you that it's from the heater and not the LED mains indicator or
teh fan.

From the size of the jump in current.

Of the LEDs on my washing machine flashing.

Ditto.

It wouldn't be that hard to separate that from the
other changes like with one of the other on/off loads
like the toaster or fridge or a hot plate coming on.

It's virtually impossible.

Very easy actually with something like say the toilet light
which has quite different time characteristics and power
characteristics than say the bedroom light etc.

rubbish.
Howq does a toilet light have differnt characteristics. ?

Its on for much shorter times more frequently than the other
lights. The only lights that come close are lights inside cupboards
and those don't aren't going to be the one that comes on every
morning in winter as people get up and have their first ****
or come on during the night as people ****.

Even with the small number of other appliances which
do vary the current they take in a continuous way, those
changes should be a lot slower than the backlight current
varying with the program content.

No they wouldn't, something switching off is switching off.

They aren't all simple on/off devices.

so how can you tell one from the other, you can't without some serious
kit measuring it at source.

It doesn't have to be done at the source, it can be
seen in the total house current, just because that
is varying much more frequently than with the
on/off devices like lights and toasters etc.


But I don't believe it would be possible to separate
out the individual backlight currents when you have
two TVs running at once showing different channels.

It wouldn't be possible to seprate the backlight current from almost
anything else in the house.

Wrong on the short term variations in that current alone.

You can't isolate them that's the problem.

Of course you can isolate them in the total house consumption.

But maybe you actually mean that with a smart meter you
don't actually have say the total house current every 4 seconds,
you actually have the total current integrated and reported back
at a rate that is nothing like every 4 seconds. Its certainly true that
with that it isn't even going to be easy to say work out exactly which
light has been turned on. Tho it will certainly be possible to work
out when at least one person has got up in the morning because
that is when the total house current starts to increase from the
minimum that is seen thru the night with an occasional spike
as someone gets up for a **** etc.

On further thought, I'm not now convinced that will even
be possible to work out what is being watched on a TV
that does modulate the backlight as the program content
changes, because all you have is the total house current
integrated, you don't have 4 second samples of the house
current. You do with the consumer addon meters that
Roland has, but the smart meters used to charge you for
the power you have used don't do it like that because
there is no point in sampling every 4 secs with those,
and there is no way to get that data out of the house
anyway, so they don't bother to collect it like that.