Analogue TV switch off starts

[Spark123]

The change over to digital only TV has started with the switching off of BBC2 in the Whitehaven area, Cumbria. The remaining channels are due to be switched off in the area up to the 14th of November.
http://www.newsandstar.co.uk/news/viewarticle.aspx?id=554058

 

[JohnD]

No prob

I got a Philips set-top-box in Tesco for £35, it gives better reception and lots more channels that analogue, using the old aerial, in this hilly area. I've cancelled my Cable TV paid-for service as Freeview gives me more than enough.

Only annoying thing is that I haven't got a TV or DVD recorder with its own digital tuner.

 

[Space cat]

The 'better reception' you get with digital TV is, for want of a better word, an illusion. There are thirty digital TV channels (though not all are used by Freeview) but they are all multiplexed into six real UHF channels. This means that each digital channel has only one fifth of the bandwidth available to its analogue counterpart.

Picture quality is maintained by a variety of tricks and it IS better as long as the signal is strong enough. It's when the signal strength drops that the weakness of the digital system is revealed. While the analogue picture remains just about watchable the digital picture breaks up into curious little squares and disappears.

This is the future of TV as we know it so we might as well get used to it. When the five analogue channels have gone off the air there will, in theory, be room for another 25 digital ones but I just have to ask myself what they'll be used for, given that there is not enough half decent TV available to fill the ones we've got already! The old joke about American TV, "a hundred channels and nothing to watch" is becoming a reality here too.

 

[bernardgreen]

The 'better reception' you get with digital TV is, for want of a better word, an illusion.

And hopefully that illusion will be exposed in the early years of the change over and some remedial action taken.

There is already talk of analogue having to be used for high definition TV signals due to the problems of digital mux broadcasting and reception.

But as the government can make a lot of money selling off the soon to be free channels to commercial operators they are not going to be totally un-biased about a re-think.

 

[oilman]

Whilst Hilary Benn uses his conference speech to announce the end of the filament light bulb to save energy, they are driving the switch to digital tv and radio which use much more power at the user end than analogue.

 

[Softus]

Picture quality is maintained by a variety of tricks and it IS better as long as the signal is strong enough.

Better? I don't see how it can be, unless you had a poor analogue signal to begin with. If the source is analogue, converted to digital for transmission, then reconverted to analogue, then are there not irrevocable quantization losses?

This is the future of TV as we know it so we might as well get used to it.

I doubt this too. You could have said the same of the migration from analogue to digital mobile phone technology, but the aggregate service now is far superior to the best that analogue was offering when it was killed.

 

[megawatt]

Better? I don't see how it can be, unless you had a poor analogue signal to begin with. If the source is analogue, converted to digital for transmission, then reconverted to analogue, then are there not irrevocable quantization losses?

It's a combination of both actually Softus a bit like the way they digitally remaster old records to clean up the background and make them cleaner sounding.

There is an expectation that the digital enhancement element of the A -> D -> A process will result in a cleaner final image to what is currently being achieved with the pure analogue signal.

I'm with you at the moment though ... A little sceptical and I think I'll wait and see

MW

 

[JohnD]

The 'better reception' you get with digital TV is, for want of a better word, an illusion.

hee heee!

Except that here, in the lee of the South Downs, Channel 5 Analogue is so weak I can't autotune it, and channel 3 is fuzzy.

But on digi, both are clear and sharp. Plus heaps of other rubbish not worth watching. Also, the digital radio reception is much better than I got on a "Pure" portable or via web.

If the illusion enables me to se the picture and hear the sound, it's a pretty good illusion.

 

[johnny_t]

The 'better reception' you get with digital TV is, for want of a better word, an illusion. There are thirty digital TV channels (though not all are used by Freeview) but they are all multiplexed into six real UHF channels. This means that each digital channel has only one fifth of the bandwidth available to its analogue counterpart.

Picture quality is maintained by a variety of tricks and it IS better as long as the signal is strong enough. It's when the signal strength drops that the weakness of the digital system is revealed. While the analogue picture remains just about watchable the digital picture breaks up into curious little squares and disappears.

This is the future of TV as we know it so we might as well get used to it. When the five analogue channels have gone off the air there will, in theory, be room for another 25 digital ones but I just have to ask myself what they'll be used for, given that there is not enough half decent TV available to fill the ones we've got already! The old joke about American TV, "a hundred channels and nothing to watch" is becoming a reality here too.

Once analogue is switched off though, it will allow 'them' to crank up the digital signal, which means that the break-up problems shouldn't happen in future.

 

[Space cat]

If the illusion enables me to se the picture and hear the sound, it's a pretty good illusion

It is a good illusion as long as the signal strength is adequate. You obviously have a very weak analogue Channel Five. You and lots of others! Ours has always been the poor relation ever since it first came on air.

Ever since Freeview appeared, I've noticed a gradual deterioration in signal strength on analogue channels coming from Pontop Pike, especially BBC2. I have an idea that they've been pinching power from them to run the new digital channels. Is there a good technical reason for this or have they been trying to nudge us towards digital?

Better? I don't see how it can be, unless you had a poor analogue signal to begin with.

The biggest weakness of analogue colour TV is in the colour. When colour TV was introduced there was no spare bandwidth left for the extra information. Two tricks are used to get around this:

1) The colour information is very low resolution. It's like taking a good quality black and white drawing then colouring it in badly. This trick works because the brain picks up on the sharp edges of the monochrome image rather than the fuzzy 'colouring in'.

2) The spectrum of the monochrome image is rather odd. Most of the energy is in bands centred on multiples of the line scan frequency with very little in the gaps. This makes sense when you consider the content of a typical TV picture. Each line is not all that different from the ones immediately above and below. The colour information has the same banded spectrum and so, with a bit of frequency shifting, it can be slotted into the gaps in the upper part of the monochrome spectrum. It works most of the time but we've all seen the false colours on striped shirts! You don't get this effect on digital TV.

What you CAN get on digital TV is the occasional 'mouse trail' effect. This happens when there is too much movement in too many multiplexed channels and it can't get down the line fast enough.

 

[gas4you]

I was always told, don't know how true it is, that channel 5 was always very poor analogue because they were forced to put ou analogue coverage as part of the licence to get onto digital, hence they kept the power to the minimum.

 

[Spark123]

From what I remember when they first started to broadcast CH5 they used the same channel which a majority of VCRs up and down the country used! They had people going around re-tuning videos.
They still haven't got around to broadcasting channel 5 around here yet, nor have they started broadcasting terrestrial digital. The only way I can get it is via sky. They have us down as changing over to digital in Oct to Dec 2009, though as it is unavailable at the moment and no signs as to when it will become available there should be some fun and games!!

 

[Steve]

Picture quality is maintained by a variety of tricks and it IS better as long as the signal is strong enough.

Better? I don't see how it can be, unless you had a poor analogue signal to begin with. If the source is analogue, converted to digital for transmission, then reconverted to analogue, then are there not irrevocable quantization losses?

This is the thing, many people dont have a very good analogue signal. An evolving problem I've noticed in recent years is the lack of any sort of fine tuning control on modern flat screen televisions. The manufacturers think their auto-tune function is brilliant, and offer no facility to fine tune it, you only get to re-arrange the channels it finds. However I suspect the fine tune wouldn't get as good a picture as older CRT tuners anyway, because the ones in LCDs and plasmas are cheap and nasty electronic things, like those PC cards (I've yet to find a PC tuner that can deliver crystal clear quality).

And distance from transmitter is also a problem. For example, I live about 6 miles from my Grandma's house. From her house, you can see Emley moor transmitter (on a clear day - its 30 miles away). Therefore she gets a cracking analogue picture even with the aerial in the loft. I mean, its crystal clear, and she has an old set with a fine funer.

At my house, with a standard 8-bar aerial, analogue is quite weak. We have this aerial pointed at Emley because it transmits ch5. Most aerials on our street point at Belmont, as its a marginally stronger signal (emley is looking back over some hills - most houses have 2 aerials for best of both). However the signal from emley is sufficient to indicate 60% signal strength on a freeview box.

My LCD screen has digi and analogue tuners, the digi is far superior picture quality from emley moor.

Another emerging problem is BLOODY CHEAP SET TOP BOXES! For Christs sake, this is one reason I never bought a freeview box. Both my grandparents have them, and both have had to return them due to power faults. Its ridiculous that they can sell such substandard stuff. And why did Sony, Panasonic, Toshiba never capture this market? Its been left to the cheap budget manufacturers like Technosonic (wonder where they got this name from???) Digihome, Logik, Matsui, Goodmands, Bush, Grundig. IT ENDS NOW!!!! I wish. I'd rather pay £100 for a decent single tuner STB from a decent brand that I knew would last me years, than pay £20 for a cheapo one from Asda.

 

[Thermo]

sorry for being thick when it comes to media technology. Once we go to digital, how can you record one program on a vcr (or a dvd for that matter) whilst watching another one?

 

[JohnD]

two tuners in one box.