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

[recneps77]

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

[stampeder]

Discussion of actual TVs is best done in 57's forums and threads.

Back to the topic please...

[tablo]

Is ATSC standard only the standard that has capablity of subchannels?

[GeorgeMx]

Originally Posted by tablo

Is ATSC standard only the standard that has capablity of subchannels?

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.

[classicsat]

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.

[RamKat]

Are they multiplexed on demand (like the DVB-T system) or are fixed bit rates assigned to each sub channel?

[holl_ands]

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/digi...ultiplexing_5/
http://broadcastengineering.com/hdtv...hd-sd-channel/
http://broadcastengineering.com/news...s-pipe-090709/
but KAXT is now down to 12 "SD" video and 3 audio channels:
http://www.avsforum.com/avs-vb/showt...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/confe...tat.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....

[RamKat]

Thanks for a as usual complete reply holl_ands

[nbound-au]

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

[stampeder]

We shouldn't be quoting posts from almost 4 years ago for replies. Anyways a general information post or update is always welcome for fresh discussion.