[Trip in VA]

Is there enough information to know what the minimum MER might be yet, or will we have to wait longer for that?

- Trip

 

[tripelo]

Is there enough information to know what the minimum MER might be yet, or will we have to wait longer for that?

Good question Trip.

Seems you are referring to a number similar to the commonly quoted minimum signal to noise ratio ratio of 15.2 dB for ATSC (post-detection, this closely relates to a 15.2 dB MER).

As you know, the method almost exclusively considered for modulation in ATSC 3.0 is a form of OFDM (Ortohoginal frequency division multiplexing). All thing being somewhat equal, in the earlier DTV transition, OFDM was found earlier to be a few dB worse for weak signal detection (around 1-2 dB). One of the main causes of this S/N difference was that OFDM required a greater peak/average ratio in the transmitter, thus for a given transmitter power; the average power that could be accommodated was less for OFDM than for ATSC.

In ATSC 3.0, it is likely that the actual reception S/N may in some cases be better than ATSC.

Multipath is likely to be much less a problem (OFDM handles multipath better than ATSC).

A few other techniques under consideration can also improve reception of the ATSC 3.0 signal:

- Hierarchial modulation. (layered modulation, can allow detection of weak signals, tradeoff for lower bit rates.)
- MISO (a subset of MIMO), a space diversity technique
- Other: Newer methods of reducing the peak transmitter power requirements for a given amount of average power.

Maybe the threshold of reception will be less defined, but overall better.

One other thing, OFDM as it has been implemented in other countries, it may have more difficulty than ATSC with some impulse noise.

The minimum MER?

A guess; we may have to wait a bit.

Would certainly like to read more discussion on the topic.

 

[dr1394]

Is there enough information to know what the minimum MER might be yet, or will we have to wait longer for that?

- Trip

No, this is just the first piece of the puzzle. It's defining a preamble that tells the receiver about the parameters of the main OFDM signal.

It's very much like the DVB-T2 P1 symbol, but with some changes. The biggest difference is using a Zadoff-Chu auto correlation sequence instead of a Golay auto correlation sequence. Zadoff-Chu is used in LTE, so it's more in vogue.

It's looking like ATSC 3.0 will be very DVB-T2 like, so assuming they try to match the 15.2 dB ATSC 1.0 figure, it's likely that the main OFDM signal will be 64QAM at 3/4 code rate. That would give a bitrate around 25 Mbps.

256QAM at 3/5 rate would about a dB worse than 15.2 dB, and would give a bitrate around 26.7 Mbps.

Ron

 

[jjeff]

It's looking like ATSC 3.0 will be very DVB-T2 like.....

Ron

Any chance that with this new standard that N. America and the rest of the world will finally be on one worldwide standard? IMO it's a shame that basically N. America(and a few other areas including Japan) have to be on a different standard than the rest of the world(DVB). It was my hope with the switch to digital that we'd have a worldwide standard but alas N. America went with ATSC while basically everyone else went with DVB...Of course Europe and other areas would probably stick with 50hz vs our 60 but that could be easily worked around, we need a worldwide standard IMO.

 

[dr1394]

Any chance that with this new standard that N. America and the rest of the world will finally be on one worldwide standard? IMO it's a shame that basically N. America(and a few other areas including Japan) have to be on a different standard than the rest of the world(DVB). It was my hope with the switch to digital that we'd have a worldwide standard but alas N. America went with ATSC while basically everyone else went with DVB...Of course Europe and other areas would probably stick with 50hz vs our 60 but that could be easily worked around, we need a worldwide standard IMO.

Seems like there's zero chance now. Although this candidate standard has many similarities to DVB-T2, it's not DVB-T2. It's a new terrestrial DTV standard.

It's looking like the Sinclair backed One Media proposal has been selected for ATSC 3.0. Here's a document with more details on the One Media website.

http://onemediallc.com/presentations/files/ONEMedia-NGBP-Physical-Layer Overview- v06.pdf

BTW, the Japanese ISDB-T standard is used in South America. Here's an interactive map of word-wide DTV standards. SBTVD-T is just a different name for ISDB-T.

http://www.dtvstatus.net/map/map.html

Ron

 

[jjeff]

BTW, the Japanese ISDB-T standard is used in South America. Here's an interactive map of word-wide DTV standards. SBTVD-T is just a different name for ISDB-T.

http://www.dtvstatus.net/map/map.html

Ron

Thanks for that map, very interesting. I didn't realize Japan wasn't using ATSC, guess I was remembering back to when they used NTSC similar to N. America.
It looks even worse than I thought, only basically N. America including Puerto Rico & HI and S. Korea are using ATSC oh and I guess DOM and El Salvador also.

 

[holl_ands]

This is probably what you are looking for, DVB-T vs DVB-T2 Performance Comparison:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB8QFjAA&url=http%3A%2F%2Fwww.svpbm.com%2Fdownloads.php%2Fid_descarga%2F1915&ei=DxRUVbOYFcnFogTT2oCYBQ&usg=AFQjCNEhJfB5RRxTgYwgMaUYPKsmUFZZOg&sig2=w1eXa28uh_UhfHNMjd4UfA&bvm=bv.93112503,d.cGU
More Details:
https://www.itu.int/ITU-D/arb/COE/2012/DTV/documents/doc2.pdf

Note that SNR for 6 MHz and 8 MHz would remain about the same if modulation format is chosen to transmit 25% lower data rate.

DVB-T and T2 are actually a LAUNDRY LIST of different formats to fit 6, 7 and 8 MHz Bandwidths throughout the world with several CHOICES of Data Rate/Coding Tradeoff, Multipath Resistance (Guard Time) and Max Vehicle Speed. And YES, there are several countries that use 6 MHz other than North America. Also note that some countries are using MPEG2 some MPEG4 and some a MIXTURE...and just to keep things interesting, there are also several different Audio Stream Formats in the "Standard"....err, I mean Chinese Take-Out Menu. Fortunately, Universal Decoder Chips (some also do ATSC & ISDB) simply read the Format Descriptor in the Transport Stream and invoke the appropriate CODEC(s). Aren't we all glad that Memory is Cheap???

 

[sneals2000]

Any chance that with this new standard that N. America and the rest of the world will finally be on one worldwide standard? IMO it's a shame that basically N. America(and a few other areas including Japan) have to be on a different standard than the rest of the world(DVB). It was my hope with the switch to digital that we'd have a worldwide standard but alas N. America went with ATSC while basically everyone else went with DVB...Of course Europe and other areas would probably stick with 50hz vs our 60 but that could be easily worked around, we need a worldwide standard IMO.

No chance.

Europe is already migrating to DVB-T2 (our second gen modulation standard), a process which started nearly 5 years ago when the UK introduced OTA HD using DVB-T2 (40.25Mbs in an 8MHz channel).

In Europe we have a mix of DVB-T (first gen modulation) and DVB-T2 (second gen modulation), and separately a mix of first gen (SD MPEG2 + MP2 audio with some AC3) and second gen (SD and HD H264 + AAC) codecs used with both modulation techniques. Some countries launched SD services in the late 90s (often 16:9 SD) using MPEG2+MP2, then added H264+AAC services to their DVB-T platforms for Pay-TV and HD, whilst others introduced (in some cases partially switched) to DVB-T2 for their HD (and in some cases H264 SD) services a decade or so later.

In the UK we have SD 16:9 MPEG2 in 24Mbs DVB-T muxes, and newer HD H264 services in the newer 40Mbs DVB-T2 muxes of the same bandwidth. SD receivers receive the first gen SD services, HD receivers receive both.

Germany is looking to replace their first gen SD 16:9 SD MPEG2 DVB-T services (launched in the late 90s/early 00s) with SD and HD services using the third gen HEVC codec carried in second gen modulation DVB-T2 muxes. There is pressure in Europe to reduce the amount of UHF spectrum used for TV to allow for more mobile data services - so there is pressure to adopt more efficient modulation and compression systems to reduce the spectrum required whilst improving quality. The other big advantage of DVB-T2 is that it allows for guard intervals long enough to allow for regional single-frequency networks, allowing multiple transmitters on the same frequency to overlap...

Japan and South America have their ISDB-T systems (Japan is MPEG2 based for TV, the newer South American version is H264 based for TV)

ATSC is very much the also-ran in the digital TV world. Canada, the USA, Mexico, South Korea and a few other places use it. China has their own standard, the whole of Europe, most of the rest of Asia and Australasia is using DVB or DVB-T2 (though some are using ISDB-T) There are 6MHz, 7MHz and 8MHz countries all using DVB-T or T2. ATSC is 6MHz only I think.

ISDB-T is a first gen modulation scheme, DVB-T2 is a second ten scheme. ATSC 3.0 will also be a second gen scheme, and by all accounts is pretty similar to DVB-T2. You do wonder if the "Not Invented Here" issue is why the US isn't going for DVB-T2, or waiting for whatever the Japanese next gen scheme is going to be (which will be optimised for 4K or 8K in 6MHz?)...

 

[sneals2000]

DVB-T and T2 are actually a LAUNDRY LIST of different formats to fit 6, 7 and 8 MHz Bandwidths throughout the world with several CHOICES of Data Rate/Coding Tradeoff, Multipath Resistance (Guard Time) and Max Vehicle Speed. And YES, there are several countries that use 6 MHz other than North America. Also note that some countries are using MPEG2 some MPEG4 and some a MIXTURE...and just to keep things interesting, there are also several different Audio Stream Formats in the "Standard"....err, I mean Chinese Take-Out Menu. Fortunately, Universal Decoder Chips (some also do ATSC & ISDB) simply read the Format Descriptor in the Transport Stream and invoke the appropriate CODEC(s). Aren't we all glad that Memory is Cheap???

Yep - though this flexibility may well be why the DVB-T/T2 standards have been so widely adopted. There are also some neat links between DVB-T/T2 and DVB-S/S2 allowing for simple remuxing between transport systems (allowing for DVB-T/T2 re-transmission of DVB-S/S2 services etc.)

 

[dr1394]

ATSC 3.0 Physical Layer Specification

The ATSC 3.0 Physical Layer Protocol specification has been published as a candidate standard.

http://atsc.org/wp-content/uploads/2015/10/S32-230r21-PHY-STD-CS.pdf

It's very similar to DVB-T2. Some improvements over DVB-T2 are:

1) Non-uniform constellations.
2) Dual matrix LDPC.
3) Enhanced MISO and MIMO.
4) 1024QAM and 4096QAM.
5) Layered Division Multiplexing.

Ron

 

[DrDon]

Threads merged and retitled.

 

[ravitzsm]

Any ideas on when we might get actual hardware?

 

[dr1394]

Any ideas on when we might get actual hardware?

From this article, it looks like LG has a demodulator chip.

http://www.tvtechnology.com/resources/0006/coming-soon-atsc-30/278850

But given that the standard isn't finished yet, it's unlikely that any other silicon vendor (for example, Silicon Labs) will have anything soon. Would you commit incredibly expensive resources to a chip when the standard may change in the middle of development?

In fact, the Physical Layer specification (the most important specification for a demodulator chip) was updated just last month.

Ron

 

[DrDon]

I'm also wondering if manufacturers WILL include 3.0 tuners anytime soon. We're already seeing companies introduce displays without ANY tuners in an effort to lower the price point. It'll depend on how much it would add to the cost of producing the set to include a tuner for a signal that's only available in Raleigh. And broadcasters aren't going to switch to a new standard until the penetration of tuners is well north of 80-90%. Chicken, meet egg.

 

[gastrof]

ATSC3 - A danger to existing equipment?

I heard, just yesterday, about a move to yet another broadcast standard in the U.S. called ATSC3. Supposedly, if it becomes a thing, we'll end up back where we started, with our existing TV tuners no good, and the need to get converter boxes or new TVs.

Why has this not been in the news? Supposedly it's only a few years away.

 

[Otto Pylot]

The coming ATSC 3.0 has been discussed in other forums for awhile now. The chances that current ATSC tuners will not be able to decode the data stream is very real and yes, external STB's may be necessary if you depend on OTA for television. Some mfrs are now selling models that do not have ATSC tuners in them. They are being called panels or displays, rightfully so, because they are not televisions.

 

[holl_ands]

FIRST, take a deep breath.....ATSC 3.0 is still in the DEVELOPMENT Phase and can't even BEGIN the "Early Adopter" Phase (for fanatics with deep pockets) until AT LEAST Next Summer when the Broadcasters and Set Mfrs [other than Samsung & LG Prototypes] can start sorting out their Software Problems in an Operational Environment.

YOU won't be impacted for "perhaps" another 5-7 years from now when Major Network ATSC 1.0 Transmitters are MAYBE phased out....there is currently NO SPECIFIC DATE that this will occur.....and by then you'll probably have ALREADY bought at least ONE New UDTV with all of the not yet available Bells-and-Whistles....

It's been in the news.....just not MAJOR Network or Newspaper News....compounded by the general LACK OF ANY SPECIFIC SCHEDULE information from ANYONE, other than vague hand waving.....which is incredibly hard to package into a News Sound Bite.

Fol. articles discuss a proposed "STRATEGY" for groups of Stations to COOPERATE so a particular ATSC 1.0 Transmitter will Broadcast say ABC and CBS [with 1-2 sub-channels and maybe also other Programs] at the same time while one of the old ATSC 1.0 Transmitters is upgraded for ATSC 3.0, also Broadcasting ABC and CBS [with ALL sub-channels and numerous OTHER Programs...esp MOBIL TV]. So "OLD" ATSC 1.0 Tuners will continue to receive signals for several years beyond the Initial Roll-Out (which MIGHT be next year in SOME locations..esp. if they are owned by Sinclair Broadcasting, an early adopter).
http://www.broadcastingcable.com/news/washington/broadcasters-petition-fcc-atsc-30-rollout/155504
http://www.tvtechnology.com/atsc3/0031/a-channelsharing-proposal-for-atsc-30/278960

BTW: UHF TV Spectrum Auction is on-going, but bids thus far are only a TENTH as much as "Expected" [by Congress to help Balance the Budget as well as Stations to change operating Frequencies]....still on-going, but NOT a good sign....and a big "I Told You So" from numerous industry estimators.....

There have been Studies re the need to have a PHASED Implementation Schedule so that a particular DMA (e.g. NYC, SF, CHI) should all changeover at the SAME TIME due to several factors, incl. Interference impacts to/from adjacent markets, aforementioned SHARED Transmitter SWAPS and numerous SHARED ANTENNA SYSTEMS (common on Mountain Top locations as well as the very complicated Empire State Bldg type structures). There is also a major constraint on the number of Trained/Certified/Experienced people who can do Antenna Swaps on Towers that are hundreds (even thousands) of feet in the air, which means these DMA-by-DMA Swaps are going to take YEARS to do the entire country [just like Analog to DTV Transition]. And Border Areas will also be delayed due to cross-border coordination issues....

Note that SOME Stations are eager to Upgrade in order to collect OTA User Statistics, esp. for MOBILE Services....so in the next several years it will be more of a Science Experiment for Early Adopters, followed by more rapid adoption as UDTV sets FINALLY implement the new HDR (High Dynamic Range) feature [MORE important than "4K"....but my Samsung UDTV requires a $100 EXTERNAL UPGRADE BOX] and maybe by NEXT year, mfrs will begin to incorporate ATSC 3.0 Tuners....and WHATEVER ELSE is revealed in the FINAL ATSC 3.0 Specs that are NOT expected to be APPROVED until the END OF THIS YEAR [hopefully...they're rarely APPROVED on time...and New AUDIO Codec timeline is already late]:
http://atsc.org/standards/candidate-standards

Note that they're trying to get FCC to ADOPT the ATSC 3.0 Specs by 1 Oct 2016...just ONE DAY after scheduled approval for MANY (but NOT ALL) Specs:
http://www.tvtechnology.com/atsc3/0031/broadcasters-seek-atsc-30-rulemaking-by-october-1/278921
[In the Engineering World, we say that the Manager is planning to Broadcast S-O-S signals when his "Success-Oriented-Scheduling" leaves his Project high and dry, with Domino impacts to ALL co-dependent Projects, since delayed Schedule invariably means Cost Increases all around]

The article points out the benefits of doing just ONE Upgrade [vice presumably current plan for Separate Upgrades] for ATSC 3.0 Waveform [with HVEC Codec...and SUBSIDIZED by Spectrum Auction] at the SAME TIME as the [NOT subsidized] Roll-out of NETWORK OTA Broadcasts at "4K" [and 1080i/p] with HDR video improvements....which would impact the ENTIRE End-To-End Production System, not just the Transmitter/Receiver Systems. [Seems like a NO Brainer to me....]

Of course, mfr's won't want to build ATSC 3.0/"4K"/HDR/NEW-Audio-CODEC DTV's until there is a sizeable number of ATSC 3.0 Stations on the air.....and Stations will be reluctant to spend money on ATSC 3.0 Transmitter Upgrades until there is a sizeable number of ATSC 3.0 Capable Viewers....so it's a tough Chicken-Egg problem....

Bear in mind that HVEC Codec is up to FOUR TIMES more Efficient than current MPEG2 Codec...hence a single ATSC 3.0 Transmitter could EASILY Broadcast ABC, CBS, NBC, FOX and FOUR MORE HD Channels at the SAME Time....as long as they remained in their current 1080i or 720p format.....OR 3-4+ Networks when the major Networks eventually upgrade to "4K" UDTV resolution....which is probably still 2-4 years away...

 

[DrDon]

Threads merged.

 

[Otto Pylot]

Excellent holl_ands! Thanks for clearing that up.