World's Digital OTA TV Standards: ATSC, DVB-T, ISDB-T, DTMB

[stampeder]

Originally Posted by sabath24

What about both resolutions, which one is best?

These worldwide systems are digital modulations, meaning that they're just different "pipeline" methods for the TV data. All of the digital standards in this thread are capable of multiple resolutions up to and including wide screen High Definition.

[Friko]

I'm really disappointed by the way Digital TV is being rolled out over here compared to the UK. I hope things change in the near future although the deadline is in 2011, thus making all the broadcasters taking their own sweet time.

On BBC News today:
http://news.bbc.co.uk/2/hi/technology/7738886.stm

[stampeder]

The European situation is quite a bit different than ours, as it was more convenient for the UK to do the kind of changeover that we are envying.

The lament about the Canadian situation has been going on here for several years, but it all boils down to the same thing: we are next door to the USA, so we have to work our system "around" their decisions as best we can.

We've taken that up in this thread, amongst many other threads over the years:

http://www.digitalhome.ca/forum/showthread.php?t=92740

[CraigWB]

Oh, I dunno, I'm not too dissappointed. Here in the GTA at least, it's pretty much rolled out, although most do not use it. For Canada as a whole - yes, I can see the progress is slow.

I enjoy about 15 or so free digital HD channels at my home in Ajax, plus the handful of SD channels.

My techie friend in england tells me he can pick up 30 or so heavily compressed digital SD channels via an antenna. no OTA HD available, only available on expensive satellite DTH.

The other thing, is number of channels does not correlate to number of hours of quality programming - they have just as much garbage on their 30 free channels as we have on our 15 - the hours of worthwhile programming is about the same. of course that's subjective.

And then there's also an annual TV tax in Britain, which costs over $250, per household per year !! - and that's just for owning a device that's capable of recieving TV signals - it's over and above any BDU subscription fees !

My friend in England is envious of me, and can't believe what we recieve for free, and is stunned it's not a popular way of recieving TV !

Or maybe the grass is always greener on the other side....

[tablo]

What do you think of future of ATSC?
Like, I mean future standard other than ATSC or improvements on ATSC.
Also, if you think of new standard of ATSC, write new functions like ATSC providing HD broadcast and subchannels which NTSC did not.

(It looks like some kind of project )

[Walter Dnes]

Since most (almost all???) digital TV sets have QAM as well as ATSC tuners, what about switching over to QAM down the road? 256 QAM is more efficient, in that you can get 2 Hi-def stations into 6 mhz WITHOUT RECOMPRESSION. I.e. 38.4 megabits for 256QAM versus 19.2 for ATSC. In 10 years or so, most American TV sets would have QAM tuners, so a ATSC-to-256QAM switchover in 15 or 20 years would be a lot easier than today's NTSC-to-ATSC switchover.

You can have twice as many channels as with ATSC... or you could auction off the 600 mhz band

[recneps77]

But isn't the reason for the half number of channels because of ATSC's extensive error correction?
QAM is fine for internal wired networks with little interference, but I dont think it's too viable for wireless broadcast

[stampeder]

tablo, you can read up on ATSC's future as they are discussing it:

www.atsc.org

[GeorgeMx]

Originally Posted by recneps77

But isn't the reason for the half number of channels because of ATSC's extensive error correction?
QAM is fine for internal wired networks with little interference, but I dont think it's too viable for wireless broadcast

You are fundamentally correct. ATSC is based on 8 VSB transmission with error correction that makes it much more robust than QAM. The ATSC (Zenith) design includes signal features to help the TV tuner lock to the signal and equalize reflections (ghosts). The signal also has a transmitter signal level boost at the carrier frequency of the NTSC video carrier and a matching notch in the tuner. The 256 QAM signal used on cable does not have these off-air adaptations and requires lower (better) signal to noise in the signal to function. Adjacent channels are carried on cable at the same level which is not the case for off-air reception.

64 QAM could have been adapted for OTA but the tuners in existing HDTV sets are designed for the benign environment of cable. Even with an OTA adapted version of 64 QAM the net data rate of the system would only be sufficient for a single HDTV channel like ATSC.

[classicsat]

Originally Posted by tablo

What do you think of future of ATSC?
Like, I mean future standard other than ATSC or improvements on ATSC.
Also, if you think of new standard of ATSC, write new functions like ATSC providing HD broadcast and subchannels which NTSC did not.

(It looks like some kind of project )

I see the improvements:

1. Go to 16VSB for at least a 50% increase in bandwidth, if the QPSK to 8PSK increases are any indication. I think today's technology could improve that, just a legacy of 8VSB receivers preventing it.

2. Go to MPEG4 compression. That speaks for itself.

3. Implement a rich interactive system like they have in Europe. Search for "MHEG". Include with that a richer guide data than PSIP allows.

[stampeder]

Originally Posted by classicsat

2. Go to MPEG4 compression. That speaks for itself.

Just within the last few months the ATSC adopted MPEG4 as an official standard, but when they did that they recognized that the change would be overwhelming at this time, so there are no plans for instituting a cutover. The goal is to eventually have home equipment be MPEG2 and 4 compatible and then allow stations to change over at their will.

[GeorgeMx]

Originally Posted by stampeder

...The goal is to eventually have home equipment be MPEG2 and 4 compatible and then allow stations to change over at their will.

I don't see these changes happening quickly - think 5 to 10 years. The set manufacturers will need an incentive to put the capability in the equipment and pay the MPEG4 license fee. They would put MPEG4 in the sets if need for compatibility with cable particularly in uses like switched digital video and video on demand.

For OTA, the place to introduce MPEG4 would be on the subchannels with a 15 megabits per second MPEG 2 HD and a 3 megabits per second MPEG4 SD service. In 10 years, the HD service could be converted to MPEG4 at 10 megabits per second in 1080i format with an SD widescreen MPEG2 simulcast for compatibility and the original MPEG4 subchannel. Eventually the MPEG2 simulcast could be dropped and the SD widescreen converted to 720P HD MPEG4.

All the foregoing is purely theoretical but should be technically possible if anyone has a business reason for doing it.

[stampeder]

Yep, I will not be holding my breath for MPEG4 OTA...

[roger1818]

If/when the broadcasters do switch to MPEG4, 1080 60p would become possible. This alone might make the switch more palatable, though it does add problems on the video production end. In the end, I think 5 to 10 years is optimistic.

The one thing that might make change easier is the short lifespan of flat panel displays compared to CRTs. In 10 years time, most of the HDTVs people are using now will be in a landfill, though many of the CRTs will still be going strong.

[99gecko]

In 10 years time, most of the HDTVs people are using now will be in a landfill, though many of the CRTs will still be going strong.

When you refer to HDTV in contrast to CRT, if you mean LCD and plasma, then I have to disagree. Older plasma technology had shorter Life Expectancy and higher luminance degradation rates, but their penetration in the market would be considered early adoption.

But LCD and plasma consumer adoption has been growing exponentially, especially since CRT's are non-existent in big box stores. Couple that with the fact that the LE of plasma and LCD is now over 60,000 hours, some even higher, it's easy to assume many of the HDTV's sold today will be in use for many years. This is much longer LE than CRT (~ 30,000 hours I believe). IMHO, what will drive consumers to newer sets in the next decade will be an increase in HD programming by the broadcasters, a desire for higher resolutions and frequencies driven by HD gaming and HT, thinner profiles, lower power consumption, lower prices, and of course "Keeping Up with the Jones' ".

Even though CRT's suffer the same phosphor dimming that plasmas do over time, a lot of the CRT's will be in the landfill for the reason's I mentioned above, when they probably could be salvaged.

So no, I don't agree that the LE of newer panels will facilitate a move to MPEG4 for OTA. If anything, I would think it will hinder it.