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

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57K views 65 replies 34 participants last post by  stampeder 
#1 ·
I would like to know what the real differences are between ATSC and DVB-T. DVB-T is the standard adopted by Europe and Asia (and perhaps other places as well?) for Digital OTA broadcasting, while ATSC is used in North America (and Japan ?)

I came back from Europe and was amazed by the number of devices now available with DVB-T tuners. Well, you have all the standard home TV Tuner add-ons (start at around $100 Cdn), but you can also find a large selection of small USB token devices (also about $100cdn or $60 or so Euros) which allow you to simply hook them up to a PC/Laptop and enjoy Digital TV anywhere.

DVB-T is also found on small portable TVs (8-10" LCD) and some DVD portable players.

The most unique thing is that reception is quite possible with a small antenna, which is maybe 6" high.





I know ATSC is mainly used here for HDTV, but it requires the same antennas as for regular NTSC OTA reception.


Will we ever see such USB key devices commonly available here in NA for ATSC reception?
 
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#33 ·
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
 
#34 ·
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....
 
#35 ·
Future of ATSC?

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 :))
 
#40 ·
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.
 
#36 ·
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 :(
 
#39 ·
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.
 
#41 ·
MPEG4 already adopted by ATSC

classicsat said:
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.
 
#42 ·
...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.
 
#44 ·
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.
 
#45 ·
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.
 
#46 ·
LCD's last for what seems like forever - unless they're damaged physically (i.e. bump/hit/smash the screen with something) or the backlight goes (just need a new backlight and it's good to go)
While CRT is the "tested and true" technology, I wouldnt stake my money on it lasting longer than my LCD
 
#49 ·
No. Any digital system using an MPEG transport stream can be broken into multiple channels. The number of channels depends on the type of program content (HD, SD) and the total available data capacity of the transport channel. I think all the digital TV broadcast systems around the world use some version of MPEG transport stream. The digital transmitters (DVB-T) in the UK have multiple SD programs but no HD as far as I know.
 
#50 ·
The UK is getting terrsitral HD in a couple of years. They have it on satellite and I think cable, and I think only one or two channels at best.

Their current digital OTA network is nearly a decade old, and owned by a private company operating under contract from the various broadcasters. They have also for that time primarily been broadcasting widescreen and TVs, including SD sets, have been widescreen. AFAIK, a large propoertion of UK residents receive their TV from antenna, compared to here and the USA, whom tend to subscribe to pay TV services.
 
#52 ·
Depends on how each station decides to configure their equipment.
If the engineering staff decides to allocate Constant Bit Rates (CBR)
to all sub-channels, then they don't "steal" bits from less busy programs.
In San Diego, this is typically used when there are none or only one
video sub-channel.

But if they configure it for Variable Bit Rates (VBR), busy programs
can "steal" bits from less busy programs.

You can look at the TSReader Output reports for US markets here:
http://www.rabbitears.info/market.php
In San Diego, KNSD and KSWB use Variable Bit Rate (VBR),
and the "unknown" report for KPBS appears to also be VBR.
Rather than reporting a Constant Bit Rate setting, when in VBR
mode, the TSR report shows the station setting a ridiculously
high bit rate (e.g. 90 Mbps!!!)....probably a maximum assigned value.

Statistical Multiplexers have been in use for many years on both Cable and OTA.
Here are some ATSC OTA experiences:
http://broadcastengineering.com/digital_handbook/broadcasting_hdtv_data_multiplexing_5/
http://broadcastengineering.com/hdtv/kxii-hd-sd-channel/
http://broadcastengineering.com/news/20-channels-19mbps-pipe-090709/
but KAXT is now down to 12 "SD" video and 3 audio channels:
http://www.avsforum.com/avs-vb/showthread.php?p=18054979
[PS: Our cable system (QAM is twice the data rate) only carries 13 SD programs.]

A Harmonic White Paper from 2002:
http://www.harmonicinc.com/view_collateral.cfm?ID=51
Note how the MPEG2 coding efficiency has improved over the years,
making it possible to stack more and more programs:
https://secure.connect.pbs.org/conf.../Presentations/Next.Gen.Video.Stat.Muxing.pdf
The H.264 (MPEG4) coding efficiency curve has only just begun to come down
from 2:1 more efficient than MPEG2 to about 3:1 more efficient....so far....
 
#54 · (Edited by Moderator)
The current multiplex for the ABC (Australian Broadcasting Corporation) in Australia:

LCN, Channel Name, Res
2, ABC 1, SD (576i)
21, ABC 1 (same as above, links to exact same datastream in the multiplex)
22, ABC 2, SD (576i)
23, ABC 3, SD (576i)
24, ABC News 24, HD (720p)
200, ABC Dig Music, DVB-T Radio
201, ABC Jazz, DVB-T Radio

Currently we use MPEG2, and the original DVB-T standard, with 7Mhz width channels
 
#56 ·
ROM1 DVB-T (Saint-Pierre et Miquelon) reception in Newfoundland

Hi everyone, I'm new here. Just a question out of interest for you all as I live in the United Kingdom so have no real knowledge myself. Just curious :D :

After France completed their digital switchover in 2011; the overseas territories including St-Pierre et Miquelon all went digital too using our European DVB-T standard with 576i 50Hz video.

Having done a bit of reading, I found that some Canadian cable providers used to pick up Saint-Pierre et Miquelon 1ère (RFO) via an antenna in Newfoundland with pretty ropey quality and carry it in their offers.

As Canadian providers are allowed to do this, I've read that with the arrival of TNT including all of the public national French channels (France 2, France 3 etc.) in the islands, Viaccess encryption has been deployed to protect the broadcasts. From what I understand though, SPM 1ère remains unencrypted. I was just curious as to whether any of you in the areas of Canada nearest to Saint-Pierre et Miquelon can receive the multiplex in DVB-T? I'm guessing DVB-T equipment is rare over though (I've never seen any ATSC equipment at all myself!)

Also, on a related (but not to OTA reception) note. I've seen that SPM 1ère is still available via Canadian cable and satellite providers via a satellite link provided by SPM Telecom on the islands. What's the quality of this like? I'm guessing the picture must be a little poor owing to transcoding from 576i at 50Hz to 480i at 60Hz?

Thanks to anyone who can give any info. :)
 
#57 ·
Hey everyone,

I moved to Sydney (Australia) so I won't be posting much relevant information over the next year. I'll be following along though to see how you're all doing.

OTA is popular here, so I might just let you know what I get when I'm able to get it.
 
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