Analog, long may it continue

Mailman

Why is everyone rushing to kill off Analog broadcasting?

Digital brings extra complexity, expense and inconvenience.
To me it seems that digital is pushed so that providers can make more money out of each user.

Why does it have to be killed off in 2007. It's serving me perfectly well as it is.

Mike 1972

Digital is the future but killing off analouge is way too premature
Most TV sets in the shops and virually ALL video recorders dont have digital tuners

Analouge should only be switched off when ALL the TV's and Videos in EVERYONE home has full digital recieving capability.

The 625 line television was introduced in the UK and Ireland in 1963 but it wasnt until the late seventies that anyone even suggested turning off the 405 line service. Parts of Britain still had 405 right up to 1985.

A similar timescale needs to be applied to phasing out analouge for a start it should be compulsary for all Videos and Colour TV's to be fitted with Digital tuners (In the case of TV's it should be initially for sets over 19inches and two years later extended to sets over 10 inches) with mass production DTT capable sets could be just as cheap as analouge only models

oneweb

Completely agree with the first post. With analog, you either have a signal, or you have something that makes do for a signal (haziness, snow, whatever). But digital is a bugger. You get the pixels, the pauses, the sound glitches and whatnot. Yeah, sure, there are some cool features of digital (having to pay for extra room cable points NOT being one of them!)

Analogue should eventually be done away with, but only when the vast majority of sets in use and on sale are in fact digital capable. And this just won't happen overnight. The timeframe for the switchoff is just too soon.

Have you noticed how soon TVs, videos etc give up the ghost? Makes it a lot easier to replace 'em with newer models... (Maybe I'm just paranoid)

watty

No-one is turning off analog in 2007.
Maybe Analog MMDS. But even in UK they are quietly pushing out turn off date due to higher sales of analog than digital, poor coverage etc and a substantial core viewers who refuse to upgrade.

Here we havn't even started DTT.

Mossy Monk

why don't the EU or the government ban the sale of analogue only televisions. they could place a ban in 2 years or so giving everyone a chance to be ready for it

watty

Why??

Analog TVs are cheaper.
Analog TVs are portable.

Only satellite transmission of Digital has a huge advantage or Analog Satellite.
Analog Satellite one Channel = 25MHz
Analog Terrestrial TV one Channel = 8MHz

The UK DTT system has about 30 Channels and huge techincal problems of coverage.

Pocket Digital portable TVs are years away.

You won't see VHS with "Digital" tuner, instead Digital Receivers with Hard Disks and/or DVD-RAM, DVDxR, DVDxRW and DVDROM.

Digital TV is NOT actually about having more quality (HD-Digital TV might be), but about saving the broadcaster or carrier bandwidth.

This means that on Satellite you get 6 to 8 "good quality" channels where one was before, or 10 channels at a bit less quality than a best analog signal would have been.


Since the Terrestrial AM TV uses 1/3 to 1/4 of Satellite FM space or bandwidth, then, AT THE SAME QUALITY Terrestrial UHF would only support 15 channels instead of 5. To fit 30 channels the quality, range and inference proofness is considerably reduced compared with Satellite, which is why coverage is MUCH poorer on DTT than on Analog UHF TV.

IMO, UHF should be kept as is with 5 analog Channels and NO digital (which in UK causes interference now on the analog Channels). The 2.5 GHZ or some other band should be used for DTT.

If the Digital MMDS band was simply called Irish DTT, and they turned off ANALOG MMDS (which would be NO LOSS), then Digital MMDS band (which IS simply DTT, but on 2500MHz instead of 700MHz) would support about 120 Channels. 90 could be Chorus / NTL pay channels and 30 could be the Irish Freeview DTT system. At present Digital MMDS (Irish DTT) is pay only and is limited to 60+ channels as it is sharing 1/2 the space with the pathetic Analog MMDS system (Simply poorly engineered AM PAL Terrestrial Analog TV on 2500MHz instead of 700MHz UHF).


RTE should close the VHF TV entirely and that space used for 120 channels or more of Digital Radio. (The UK DAB allocation is too small).

Richard

Originally posted by watty

RTE should close the VHF TV entirely and that space used for 120 channels or more of Digital Radio. (The UK DAB allocation is too small).

I seem to recall that RTE can't use this space without international agreements. ROI's current allocation is even small than the UK's IIRC.

Mike 1972

If RTE shut their high power VHF transmitters it would be fairly easy for them to get international agreement for extended DAB given that the power of a DAB signal is far lower and unlikely to ever cause interference on the continent.

RE: Analouge TV's being cheaper Yes but if TV's were required to have DTT tuners mass production would mean that prices would drop. (Initially the requirement could be limited to Video recorders and TV's over 19inches and a couple of years later broadned to include portable sets) SCART sockets could still be used for VHS.

Using 2.5-2.8 GHz for DTT is a non starter. apart from the coverage problems few countries in Europe have this band available for broadcast use

There is a precedent for compulsary DTT tuners namely UHF in the States. When UHF TV started in the USA very few stations were able to make money (this despite the fact that people were clamoring for new TV stations and the VHF band was already overcrowded) one of the reaasons for this is that only "upmarket" TV sets had UHF tuners. Eventually Cogress passed the "All channel (reciever) act 1964" requiring TV sets to be capable of recieving all VHF and UHF frequencies and despite protests by manufacturers (who claimed that TV set prices would rise by up to 15%) there was no increace in the price of TV sets and UHF broadcasting (eventually) started to take off.

Oh there is a second DAB allocation at around 1.5 GHz but few (if any) countries have started using it. If when they do they should use MPEG2 or even MPEG4 rather than the crappy MPEG1 system that existing DAB is stuck with

oneweb

wow, thx for the technical details

Here was me thinking digital broadcasting implied superior image quality over analogue. If I can ask, is that why pans of scenes (for example, some Simpsons bits, Scrubs et all that do fast pans), appear so pixelated, because the original broadcaster is using greater compression? Or is it a case that the signal is recompressed by NTL etc when they get their mitts on it? Or do I have it all wrong?

watty

If video is converted from NTSC to PAL you use a digital frame store. The lines are interpolated to give 576 (active on 625) from 480 lines (active on 525 line NTSC). The 30 fps / 60Hz interlaced has to be "averaged" to 25fps / 50Hz.

So due to interlace and interframe averaging motion esp horizonatal pans is worst.

Unfortunately for MPEG coding (or worse recoding if the US show was in MPEG 720 x480 x "NTSC" coding 30/60) large movement needs the most bandwidth and will create noticable artifacts if the picture is alread strange from conversion.

It isn't as noticable as NTSC / PAL conversion was 30 years ago.

Of course if you buy R1 DVDs or live in America you have to watch 480 line instead of 576 line resolution with inferior colour encoding all the time.


If MPEG2 is decoded to analog and recoded again artifacts are worse.

Especially if done in real time on a cheap encoder that does not buffer enough for motion estimation to correctly pick key frames. That's why DV cameras use MJPEG type compression at only 5:1 rather than MPEG2 at 250:1
And why I think Tivo connected to a Digibox or Digital Cable box is seriously bad idea (it has poor real time MPEG2 compressor rather than MJPEG. Sky+ simply records the already compressed satellite signal "as is" so does not add recoding artifacts).

watty

Many countries are using 2.5Ghz for Digital MMDS/ Metropolitan Wireless WAN systems. It is a form of DTT.

Mike 1972

Here was me thinking digital broadcasting implied superior image quality over analogue.

In theory yes
in practice (because the broadcasters compress the signal so much to cram in more channels) it is usually worse

If I can ask, is that why pans of scenes (for example, some Simpsons bits, Scrubs et all that do fast pans), appear so pixelated, because the original broadcaster is using greater compression?
Or is it a case that the signal is recompressed by NTL etc when they get their mitts on it?

Probably both !

Antenna

"If RTE shut their high power VHF transmitters it would be fairly easy for them to get international agreement for extended DAB given that the power of a DAB signal is far lower and unlikely to ever cause interference on the continent"

Mike, they could extend possible DAB services without having to do the above.
There are only a small number of VHF TV sites and it would be possible to reuse VHF Band 3 TV frequencies for one area of the country as DAB frequencies in other areas.

For example Channel D (an 8MHz block) which is used in the Mullaghanish service area (for RTE1).

This 8MHz block could be used for DAB in Dublin and many other areas of the country without affecting RTE VHF TV or vice-versa.

BTW when RTE were testing DAB in Dublin was there any problem with ingress/leakage interference to/from cable TV??
This was one of the reasons for the DAB testing, but what the results were I do not know.

Mike 1972

Cable ingress/egress shouldnt have anything to do with people using frequencies.

The Dublin cable network is notoriously leaky for the simple reason that its a pile of crap and it wouldnt be allowed operate in this manner in just about any other country in the world

John R

Originally posted by Mike 1972
Cable ingress/egress shouldnt have anything to do with people using frequencies.

The Dublin cable network is notoriously leaky for the simple reason that its a pile of crap and it wouldnt be allowed operate in this manner in just about any other country in the world

Like it or not ntl is the main source of tv for a majority of Dubliners and interfering with it for DAB would upset many more people than it would please.