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post #2101 of 2258 Old 09-03-2019, 07:41 PM
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Originally Posted by mikemikeb View Post
That's the idea of a Single Frequency Network: One can have multiple towers in an area transmitting a given signal.
I get that, and how an SFN would co-located on cell towers, but where this goes off the deep end is where it's somehow combined with a 5G network, as opposed to just sharing physical tower infrastructure with 5G providers, which may make sense in some markets and applications. Since you can't split the 6mhz of spectrum, that whole scenario makes no sense. Even if you could, it would negate most of the advantage of ATSC 3.0.

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Yes, but apparently for broadcast TV, that ATSC 1.0 or 3.0 signal must be on the air for online viewings to count in the Nielsen ratings.
Which it would be.
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post #2102 of 2258 Old 09-03-2019, 08:57 PM - Thread Starter
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Here's a presentation showing the concept.


http://www.terjin.com/dl/summit/Summ...kmann-Jens.pdf


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post #2103 of 2258 Old 09-03-2019, 08:59 PM
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I'm confused by the discussion of SFN. My understanding is one of the benefits of ATSC 3.0 is it allows stations that use low power repeaters to extend coverage, such as WENH here in NH, to operate all transmitters on the same frequency.

What I'm missing is how this plays with 5G cellular? Sounds like the discussion is that ATSC 3.0 allows the 6MHz of TV channel bandwidth to be split into a TV portion and 5G cellular portion.

/tom
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post #2104 of 2258 Old 09-03-2019, 11:40 PM
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Originally Posted by BiggAW View Post
I get that, and how an SFN would co-located on cell towers, but where this goes off the deep end is where it's somehow combined with a 5G network, as opposed to just sharing physical tower infrastructure with 5G providers, which may make sense in some markets and applications. Since you can't split the 6mhz of spectrum, that whole scenario makes no sense.
You can definitely split all 6 MHz by time, not by spectrum, within the 3.0 spec. See below reply.

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I'm confused by the discussion of SFN. My understanding is one of the benefits of ATSC 3.0 is it allows stations that use low power repeaters to extend coverage, such as WENH here in NH, to operate all transmitters on the same frequency.

What I'm missing is how this plays with 5G cellular? Sounds like the discussion is that ATSC 3.0 allows the 6MHz of TV channel bandwidth to be split into a TV portion and 5G cellular portion.
It can do both of what you're describing. Basically the main tower and repeaters can operate what are known as "physical layer pipes", which are, under the 3.0 spec, sent by time slices. So PLP 1 can have TV signals, and a few milliseconds later, there can be a second PLP which can have 5G content. All of this is coordinated from the bootstrap. Then from there, the cell companies can use their 5G towers as low power repeaters that will rebroadcast the PLP 1 TV signal, timed up with the main tower, while the 5G content goes on PLP 2. Alternately, the TV stations can set up low-power repeaters on their own. In theory, both cell companies and TV stations can set up their own repeaters, but that's not usually going to happen because a cell company's repeaters would usually be enough to provide solid TV coverage. My theoretical scenario of "set 5 MHz aside for exclusive 5G use", still allows for these repeaters to be used, and TV signals timed up, just the 5G signal does what it does without need for a 3.0 decoder chip, and hopefully TV signals on the remaining 1 MHz can still be decoded by 3.0 tuners.

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You can't split the spectrum. The minimum size of an ATSC 3.0 signal is 6 MHz. That's cast in concrete in the bootstrap specification.
I mean yes, the 3.0 spec claims a 6 MHz minimum spectrum, but if the overall signal being received by a tuner is 6 MHz wide, I can't help but think the tuner could, and should, decode what it can understand within a given PLP time slice, even if most of what it sees is nonsense. Or what if one is using an antenna whose gain falls off the map past a certain point? If a tuner picks up enough data, including the bootstrap, to theoretically decode a TV station's signal, but can't see all 6 MHZ of the signal, it's not supposed to decode the usable signal it can see? That sounds like a bad decoder to my opinion, especially in the latter situation.

Offering a few MHz of spectrum in a low-frequency band won't magically get 3.0 OTA TV tuners into phones. Verizon and AT&T simply will not agree to putting a Trojan horse into their phones. It's not going to happen, because they own cable companies that have to negotiate with Sinclair for retrans deals, and if your cell/cable company makes it easier for people to get TV through an end-around, it's going to increase Sinclair's leverage in retrans negotiations. So VZ and ATT simply will not swallow a poison pill from their perspective. Sprint is cash-strapped and in the process of being purchased by T-Mobile. T-Mobile might want to do an arrangement of some kind, because they're not in the cable TV business for now, but I'm not sure they'd want to have the tuners in there, because they'd want to have an ability to control the pipes used to receive content on phones, so to speak. So they'd probably want to do some sort of deal, but if their tech boffins can find a way to make a 3.0 tuner tune a TV signal on a net 1 MHz of spectrum, they'd force Sinclair's hand. Who else would negotiate with them?

Maybe, maybe, T-Mobile would agree to a deal to include 3.0 chips if all phones included with tuners didn't have hardware or software support for the HEVC and AC-4 codecs, or at least AC-4. To allow for HEVC decoding of content it would control pipe access to (Netflix, YouTube, etc.), would T-Mobile be OK with video decoding, but not audio decoding, of TV signals?
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post #2105 of 2258 Old 09-04-2019, 03:11 PM
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Originally Posted by mikemikeb View Post
You can definitely split all 6 MHz by time, not by spectrum, within the 3.0 spec. See below reply.
This just keeps getting loonier and loonier.
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post #2106 of 2258 Old 09-05-2019, 09:25 AM
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Curious how the ATSC 3.0 transition is going to work with the repack that is underway. I live in the Boston DMA and we've had the majority of our repack take place. Any station that begins ATSC 3.0 transmission is supposed to duplicate 1.0 transmission for 5 years. With the repack, it seems the Boston DMA doesn't have any channels remaining when taking into account surrounding DMAs. Someone on the Boston OTA thread listed all the RF stations that aren't in use in Boston but will be used by surrouding DMAs and so can't be used in Boston.

Where is the bandwidth/channels supposed to come from? Without shutting down all the subchannels like Decades, MyTV etc., or having the 1.0 or 3.0 broadcast in something less than 1080p, I don't see how this is going to work.

Thanks for any info.
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post #2107 of 2258 Old 09-05-2019, 02:12 PM
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Originally Posted by pnkflyd51 View Post
Curious how the ATSC 3.0 transition is going to work with the repack that is underway. I live in the Boston DMA and we've had the majority of our repack take place. Any station that begins ATSC 3.0 transmission is supposed to duplicate 1.0 transmission for 5 years. With the repack, it seems the Boston DMA doesn't have any channels remaining when taking into account surrounding DMAs. Someone on the Boston OTA thread listed all the RF stations that aren't in use in Boston but will be used by surrouding DMAs and so can't be used in Boston.

Where is the bandwidth/channels supposed to come from? Without shutting down all the subchannels like Decades, MyTV etc., or having the 1.0 or 3.0 broadcast in something less than 1080p, I don't see how this is going to work.

Thanks for any info.
So the idea is lighthouse/nightlight. Some 1.0 channels are already sharing, more would share, opening up a 3.0 channel for several stations to share (lighthouse). Over time, the 1.0 signals would be more and more compressed, while more channels are moved to 3.0, until there is only one 1.0 station left (nightlight). That's in theory if all the channels cooperate perfectly.

How will it work in practice? Who the heck knows. Many of the 1.0 stations already have 2HD/2SD or even more, so they have little additional room for more channels. It's unknown if all channels will convert to 3.0, or if we'll end up with both for a long time. In some smaller markets, the channels might just decide that one or two transmitters are fine, and leave the rest of the spectrum empty (or for TVWS to use). NYC and Philly are the two most congested markets, but really all of BOS-WAS is quite congested.
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post #2108 of 2258 Old 09-05-2019, 03:37 PM
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Originally Posted by BiggAW View Post
So the idea is lighthouse/nightlight. Some 1.0 channels are already sharing, more would share, opening up a 3.0 channel for several stations to share (lighthouse). Over time, the 1.0 signals would be more and more compressed, while more channels are moved to 3.0, until there is only one 1.0 station left (nightlight). That's in theory if all the channels cooperate perfectly.

How will it work in practice? Who the heck knows. Many of the 1.0 stations already have 2HD/2SD or even more, so they have little additional room for more channels. It's unknown if all channels will convert to 3.0, or if we'll end up with both for a long time. In some smaller markets, the channels might just decide that one or two transmitters are fine, and leave the rest of the spectrum empty (or for TVWS to use). NYC and Philly are the two most congested markets, but really all of BOS-WAS is quite congested.

As crazy as it seems, there are TWO RFs in Indianapolis that could easily be 3.0, I THINK.
I'm not an industry insider or any type of expert, but I know RF17 (moving to RF 26) broadcasts exactly the same shows as RF 9, albeit to a smaller area, and RF 46 (oddly moving to RF17) for some unknown reason broadcasts only 13-2 (MeTV), a 480i subchannel. Surely somebody can figure out a way to use one of the two for ATSC 3.0.
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post #2109 of 2258 Old 09-05-2019, 05:29 PM
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Originally Posted by mikemikeb View Post
Yes, that's basically the concept. However, I wonder if the standard allows for the cell carriers to put their own 5G header, and quarantine a set 5 MHz section of the 6 MHz section for themselves, which a cell phone could pick up without the need for an ATSC 3.0 tuner? (The 3.0 bootstrap, and the rest of the spectrum, would remain for OTA TV reception.) That way, the cellcos can say, "OK, we'll pay you $$xyz for spectrum on your TV signal, and we'll piggyback your ATSC 3.0 TV signal as a Single Frequency Network, but in exchange, we won't place 3.0 tuners on our phones." I think that would be an overall win-win for both sides, maybe not quite what Sinclair would want, but still a big revenue stream for them (and more like two, if they want to do a "pay for 1080p/4K" package).
Not sure I grok what you're saying. Are you saying that ATSC 3.0 stations would take 5/6 of the spectrum in their licensed signal (5MHz out of their station's 6 MHz of spectrum) and turn that over to one or more 5G network operators (e.g. T-Mobile), who could then use that for whatever purposes they wanted, so long as they included one or more of the station's broadcast TV streams (presumably as multicast IPTV via 5G)?

And then the station itself would use the remaining 1/6 of their spectrum for actual free OTA TV distribution to TV antennas? I guess that would be enough to run a single 1080p HDR channel but nothing more.

First off, does current law/FCC regs allow ATSC 3.0 licensees to essentially just become fronts for 5G cellular networks in this way? IDK, maybe anything goes in the Trump/Pai era at the FCC.

But even if that was allowed, I'm not sure from a business perspective that I see TV stations wanting to give away THAT much of their spectrum/bandwidth just to get carriage on cell phones of their main TV signal. Although if that 5/6 share was taken down to something under half, maybe the economics would work. But would the 5G operators be interested? Hmmm...

EDIT: OK, I had been away from this thread for several days and I posted my response your quoted post above before reading through subsequent discussion. It looks like I DID grok what you were saying and, business considerations aside, it seems that your proposed idea is not feasible because of FCC regs, the ATSC 3.0 standards, and/or plain ol' science, per dr1394's responses. (I'm a simple unfrozen caveman lawyer and do not understand your advanced concepts of "wireless physics".)

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post #2110 of 2258 Old 09-05-2019, 06:13 PM
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Originally Posted by mikemikeb View Post
I mean yes, the 3.0 spec claims a 6 MHz minimum spectrum, but if the overall signal being received by a tuner is 6 MHz wide, I can't help but think the tuner could, and should, decode what it can understand within a given PLP time slice, even if most of what it sees is nonsense. Or what if one is using an antenna whose gain falls off the map past a certain point? If a tuner picks up enough data, including the bootstrap, to theoretically decode a TV station's signal, but can't see all 6 MHZ of the signal, it's not supposed to decode the usable signal it can see? That sounds like a bad decoder to my opinion, especially in the latter situation.

Offering a few MHz of spectrum in a low-frequency band won't magically get 3.0 OTA TV tuners into phones. Verizon and AT&T simply will not agree to putting a Trojan horse into their phones. It's not going to happen, because they own cable companies that have to negotiate with Sinclair for retrans deals, and if your cell/cable company makes it easier for people to get TV through an end-around, it's going to increase Sinclair's leverage in retrans negotiations. So VZ and ATT simply will not swallow a poison pill from their perspective. Sprint is cash-strapped and in the process of being purchased by T-Mobile. T-Mobile might want to do an arrangement of some kind, because they're not in the cable TV business for now, but I'm not sure they'd want to have the tuners in there, because they'd want to have an ability to control the pipes used to receive content on phones, so to speak. So they'd probably want to do some sort of deal, but if their tech boffins can find a way to make a 3.0 tuner tune a TV signal on a net 1 MHz of spectrum, they'd force Sinclair's hand. Who else would negotiate with them?

Maybe, maybe, T-Mobile would agree to a deal to include 3.0 chips if all phones included with tuners didn't have hardware or software support for the HEVC and AC-4 codecs, or at least AC-4. To allow for HEVC decoding of content it would control pipe access to (Netflix, YouTube, etc.), would T-Mobile be OK with video decoding, but not audio decoding, of TV signals?
Well, I give you kudos for at least proposing an interesting "what-if" thought experiment. For various reasons, I'm skeptical that what you're talking about could or will come to pass but, hey, it was interesting (and educational) reading about how ATSC 3.0 stations might try to work with the coming world of 5G.

But your very complicated potential scenario brings me back to a question that I posed earlier: why should TV broadcasters now hitch their wagon to ATSC 3.0 as opposed to regular ol' 5G (with the ability to employ multicast video over it via FeMBMS)? If the goal is full compatibility with IP devices, including the ability to reach cellular smartphones without the need for a special TV tuner chip to be embedded in them, it seems that skipping ATSC 3.0 in favor of 5G would be a better path. Of course it would require getting the FCC on board, but why couldn't there be a special class of 5G network operators (i.e. "local TV stations") who devote a minimum amount of their bandwidth to unlocked free multicast video plus advanced public alerts? In return, all 5G radio chips would be required to support that class of 5G frequencies. And then they could exploit the remainder of their bandwidth as they wanted, either alone or in collaboration with other businesses (including regular commercial 5G network operators).
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post #2111 of 2258 Old 09-06-2019, 07:10 AM
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As crazy as it seems, there are TWO RFs in Indianapolis that could easily be 3.0, I THINK.
I'm not an industry insider or any type of expert, but I know RF17 (moving to RF 26) broadcasts exactly the same shows as RF 9, albeit to a smaller area, and RF 46 (oddly moving to RF17) for some unknown reason broadcasts only 13-2 (MeTV), a 480i subchannel. Surely somebody can figure out a way to use one of the two for ATSC 3.0.

RF46 cannot be used any more. The FCC repack is moving everyone to 36 and below.
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post #2112 of 2258 Old 09-06-2019, 07:24 AM
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RF46 cannot be used any more. The FCC repack is moving everyone to 36 and below.

That's right, they've moving 46 to 17, which seems odd because 17 is moving to 26. Weird science...
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post #2113 of 2258 Old 09-06-2019, 07:41 AM
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That's right, they've moving 46 to 17, which seems odd because 17 is moving to 26. Weird science...
I was born in Muncie and grew up in central Indiana. We could get channels 13 and 8 most of the time. What was the abc affiliate? Channel 6 maybe? We couldn't get it well.

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post #2114 of 2258 Old 09-06-2019, 10:24 AM
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That's right, they've moving 46 to 17, which seems odd because 17 is moving to 26. Weird science...
There's method to their madness. The station currently on RF 46 (WALV-CD) fits better with surrounding markets on RF 17 than the station currently on RF 17 (WISH) does, and RF 26 doesn't pose any problems with surrounding markets for WISH.

Because WALV is a low power station, WPBI-LD in Lafayette can also use RF 17 without interfering.

WPBI has to leave RF 16 so WDNI-CD can move from RF 19 to RF 16. Apparently WPBI is more compatible with Indy stations on RF 17 than it is on RF 16. At any rate, WDNI moving frees up RF 19 for WIPB Muncie to use, which, in turn, clears RF 23, WIPB's old frequency, for WDTI to use, since they can no longer use RF 44.

Head hurt yet?
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post #2115 of 2258 Old 09-06-2019, 10:57 AM
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There's method to their madness. The station currently on RF 46 (WALV-CD) fits better with surrounding markets on RF 17 than the station currently on RF 17 (WISH) does, and RF 26 doesn't pose any problems with surrounding markets for WISH.

Because WALV is a low power station, WPBI-LD in Lafayette can also use RF 17 without interfering.

WPBI has to leave RF 16 so WDNI-CD can move from RF 19 to RF 16. Apparently WPBI is more compatible with Indy stations on RF 17 than it is on RF 16. At any rate, WDNI moving frees up RF 19 for WIPB Muncie to use, which, in turn, clears RF 23, WIPB's old frequency, for WDTI to use, since they can no longer use RF 44.

Head hurt yet?

Naw, my head is fine Dave. Gave up about half way through the first paragraph!
Seriously, this whole repack thing is absolutely amazing, and I'm afraid this may just be the beginning of a few more rounds. Lo VHF anyone?
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post #2116 of 2258 Old 09-06-2019, 11:51 AM
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Somewhere on this thread a couple years or more ago, I posted about the possibility that, based on my understanding of the ATSC 3.0 specs, broadcasters might distribute via their 3.0 OTA tower a base-level HD SDR signal, while also streaming a complementary upgrade-level signal via the internet. When combined in real time by the 3.0 tuner, the two bitstreams would combine to create 4K HDR video on the screen.

Looks like Sinclair has been actively testing it out and it works well.

ONE Media Testing Demonstrates Viability Of ‘Mobile First’ Strategy
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post #2117 of 2258 Old 09-06-2019, 02:35 PM
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Somewhere on this thread a couple years or more ago, I posted about the possibility that, based on my understanding of the ATSC 3.0 specs, broadcasters might distribute via their 3.0 OTA tower a base-level HD SDR signal, while also streaming a complementary upgrade-level signal via the internet. When combined in real time by the 3.0 tuner, the two bitstreams would combine to create 4K HDR video on the screen.

Looks like Sinclair has been actively testing it out and it works well.

ONE Media Testing Demonstrates Viability Of ‘Mobile First’ Strategy

Until a gust of wind causes pixelation from the antenna.
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post #2118 of 2258 Old 09-07-2019, 01:58 AM
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If the goal is full compatibility with IP devices, including the ability to reach cellular smartphones without the need for a special TV tuner chip to be embedded in them, it seems that skipping ATSC 3.0 in favor of 5G would be a better path. Of course it would require getting the FCC on board, but why couldn't there be a special class of 5G network operators (i.e. "local TV stations") who devote a minimum amount of their bandwidth to unlocked free multicast video plus advanced public alerts? In return, all 5G radio chips would be required to support that class of 5G frequencies. And then they could exploit the remainder of their bandwidth as they wanted, either alone or in collaboration with other businesses (including regular commercial 5G network operators).
Perhaps if the ATSC started to design the ATSC 3.0 spectrum, today, then they could have tried that. However, the "5G NR Standalone" (official name) radio interface is very new, and not proven in the field. ATSC went with a radio interface (OFDM) that is tried and true through decades of deployment around the world, with a few twists to adapt to the Internet age, including an IP interface. That standard took years to develop. It's probably the best that could be done right now.

Also, under your concept, I assume the main TV tower would broadcast in the 5G radio interface? If so, then great, because the concept behind Advanced Emergency Alerting (AWARN) is that if the local cell towers are taken offline, you'll be OK and still get reception from the main TV tower, because the TV broadcaster has special financial incentive to stay on the air. This is a situation that happened during California wildfires in 2017, where the fires cut off cell towers from alerting local residents to evacuate. https://scientists4wiredtech.com/201...2017-ca-fires/

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As crazy as it seems, there are TWO RFs in Indianapolis that could easily be 3.0, I THINK.
I'm not an industry insider or any type of expert, but I know RF17 (moving to RF 26) broadcasts exactly the same shows as RF 9, albeit to a smaller area, and RF 46 (oddly moving to RF17) for some unknown reason broadcasts only 13-2 (MeTV), a 480i subchannel. Surely somebody can figure out a way to use one of the two for ATSC 3.0.
As a Class A station, WALV can flash-cut to ATSC 3.0 without any need to set up a retransmission agreement of 46-1, not that it's needed, here. So expect that to be the local 3.0 feed for WTHR, probably with the signal sent more robust than a typical full-power 3.0 signal, to account for the lower transmission power. Using 16-QAM instead of 64QAM gives you about a 5 dB improvement in signal reception, but with an 8.18 kW signal on UHF 17, I doubt that's going to help much. I wonder if WALV will file to increase their power?
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post #2119 of 2258 Old 09-07-2019, 03:41 AM - Thread Starter
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However, the "5G NR Standalone" (official name) radio interface is very new, and not proven in the field.
Sorry to be correcting you again. 5G ended up choosing regular Cyclic Prefix OFDM for the downlink (the same as 4G LTE). There was a lot of talk about OFDM tweaks (Windowed-OFDM, Filtered-OFDM, Universally Filtered-OFDM, Unique Word OFDM, Pulse Shaped OFDM, Filter-Bank OFDM), but all were rejected.

For 5G, the OFDM parameters have been extended for wider bandwidths. For 4G LTE, the subcarrier spacing is 15 kHz and the maximum number of subcarriers is 1200. For 5G, the subcarrier spacing can be 15 kHz, 30, kHz, 60 kHz, 120 kHz or 240 kHz and the maximum number of subcarriers is 3300. The maximum bandwidth is 3300 * 240 kHz = 792 MHz (800 MHz channel size).

HD MPEG-2 Test Patterns http://www.w6rz.net
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post #2120 of 2258 Old 09-08-2019, 02:16 AM
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Originally Posted by ElevatorSkyMovie View Post
Until a gust of wind causes pixelation from the antenna.
I've been watching DVB-T COFDM (16QAM and 64QAM 2k, then 64QAM 8k) since 1999 and DVB-T2 COFDM (32k 256QAM) since 2009. I've never seen pixellation caused by wind on my rooftop antenna. My early DVB-T tuner used to suffer a bit from high-frequency spikes (poorly suppressed power switching for instance), and 64QAM 2k was the least robust solution (i.e. was trickier to receive in fringe areas at the low powers then in use to co-exist with analogue PAL). Not seen that for many, many years.

AIUI ATSC 3.0 RF resembles DVB-T2 COFDM to a reasonably large degree. What makes you think wind would cause pixellation on ATSC 3.0? Or is it because you guys use much larger rooftop antennas for VHF and UHF and need to use higher gains that your antennas have more windage?
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post #2121 of 2258 Old 09-08-2019, 03:59 PM
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With ATSC 1.0, the problem that wind causes is that it moves trees around, thus altering the multipath patterns received at the antenna. ATSC 1.0 tuners often can't compensate; thus pixelation when the wind blows.

You're right; that probably won't be a problem with ATSC 3.0 - or at least, not as much of a problem.

But will NashGuy's idea work on a large scale? Perhaps, but the bigger problem I see isn't with the OTA signal, but with the "4K upgrade" Internet stream, which is inevitably going to be delayed, suffer drop-outs, etc., particularly in the US where few have anywhere near "real-time" Internet connectivity.

The concept can still work though - in theory, it could even be made to work with ATSC 1.0: just delay the OTA broadcast a bit, so that most Internet connections will be "ahead" of the OTA signal, then the tuner can buffer enough "4K upgrade" data to ride out most Internet delays and drop-outs.

And there's another reason it might very well "work" despite those pitfalls. I suspect northward of 90% of viewers would not even notice if the "4K upgrade" stream dropped out and their program's resolution dropped to "only" 1080i!
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post #2122 of 2258 Old 09-09-2019, 01:07 AM
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Quote:
Originally Posted by dr1394 View Post
Sorry to be correcting you again. 5G ended up choosing regular Cyclic Prefix OFDM for the downlink (the same as 4G LTE). There was a lot of talk about OFDM tweaks (Windowed-OFDM, Filtered-OFDM, Universally Filtered-OFDM, Unique Word OFDM, Pulse Shaped OFDM, Filter-Bank OFDM), but all were rejected.

For 5G, the OFDM parameters have been extended for wider bandwidths. For 4G LTE, the subcarrier spacing is 15 kHz and the maximum number of subcarriers is 1200. For 5G, the subcarrier spacing can be 15 kHz, 30, kHz, 60 kHz, 120 kHz or 240 kHz and the maximum number of subcarriers is 3300. The maximum bandwidth is 3300 * 240 kHz = 792 MHz (800 MHz channel size).
No need to apologize. What you explain may be why, in my research for the previous post, that it mentioned that the non-standalone 5G service has similar latency and speed to LTE, when used at under 6 GHz. What's the difference between standalone and non-standalone 5G, and what gives standalone 5G a superior claimed latency over LTE? Does 5G's speed and/or latency advantage go away, even in the standalone interface version, at frequencies under 6 GHz?

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Originally Posted by JHBrandt View Post
I suspect northward of 90% of viewers would not even notice if the "4K upgrade" stream dropped out and their program's resolution dropped to "only" 1080i!
They might notice a difference because of the Rec. 2100 color scheme in ATSC 3.0. Rec. 2100 provides lots more color palette and dynamic range over Rec. 709.

One other note: In ATSC 3.0, 1080p/60 and 4k/24p or 4k/30p will have similar bitrates for similar perceptual per-pixel quality, and the HDR doesn't add much bitrate onto things; I wouldn't be shocked if naturally-1080i broadcasters (NBC, CBS) are all but forced into 1080p-base progressive mode, and alternate between those two formats for free to viewers (maybe a pay-for-4K/60 option via an Internet-based PLP with conditional access). Rec. 2100 technically isn't supported in 720p, giving 720-friendly broadcasters (Sinclair) an advantage in providing a "pay-to-play" 1080p or 4K experience, in part to get the enhanced color in the first place. What Fox does will be interesting. What will PBS do? Will it be up to member stations, or will PBS put down the hammer to make it all for free?
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post #2123 of 2258 Old 09-09-2019, 02:30 AM
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Quote:
Originally Posted by mikemikeb View Post
Rec. 2100 technically isn't supported in 720p, giving 720-friendly broadcasters (Sinclair) an advantage in providing a "pay-to-play" 1080p or 4K experience, in part to get the enhanced color in the first place. What Fox does will be interesting. What will PBS do? Will it be up to member stations, or will PBS put down the hammer to make it all for free?
That's odd. BBC iPlayer UHD content - which is 2160p Rec 2020 HLG HDR (which is a Rec 2100 combo) is streamed via MPEG DASH at 2160p50, 1440p50, 1080p50 and 720p50 - all with the same colour gamut and EOTF. (I think 540p50 is also an option but I don't think I have seen it in any DASH manifests)

(I guess the combo of Rec 2020 gamut and an HLG EOTF can be used at any resolution - but in 720p50 mode may not be defined specifically in the Rec 2100 spec?)
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post #2124 of 2258 Old 09-09-2019, 08:21 PM - Thread Starter
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Quote:
Originally Posted by mikemikeb View Post
No need to apologize. What you explain may be why, in my research for the previous post, that it mentioned that the non-standalone 5G service has similar latency and speed to LTE, when used at under 6 GHz. What's the difference between standalone and non-standalone 5G, and what gives standalone 5G a superior claimed latency over LTE? Does 5G's speed and/or latency advantage go away, even in the standalone interface version, at frequencies under 6 GHz?
We're getting a bit off topic, so I'll keep it short.

Non-standalone means that all of the control is done over the 4G LTE network and only data is transferred over the 5G network. I believe all current 5G deployments are non-standalone.

There's three contributors to latency. The air latency, which is handset to tower. The radio network latency which is tower to Internet. And then there's the latency of the Internet itself.

There's some tricks at layer 2 to reduce air latency and just having more bandwidth helps. I wouldn't be surprised if the layer 2 stuff gets "back ported" to LTE.

The real latency gains are going to be from rearchitecting the radio network. Basically moving stuff closer to the tower.

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post #2125 of 2258 Old 09-10-2019, 10:59 AM
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Perhaps if the ATSC started to design the ATSC 3.0 spectrum, today, then they could have tried that. However, the "5G NR Standalone" (official name) radio interface is very new, and not proven in the field. ATSC went with a radio interface (OFDM) that is tried and true through decades of deployment around the world, with a few twists to adapt to the Internet age, including an IP interface. That standard took years to develop. It's probably the best that could be done right now.
Yes, good point. I suppose at any point in time, one could look ahead and say "But some new form of technology is on the horizon. Shouldn't we wait for that instead?"

It's not that I'm criticizing ATSC 3.0 for what it is, given the point in time when it began to be conceived and hashed out. It's more that I'm wondering if broadcasters (and regulators and industry observers/leaders) aren't asking if it would be a strategic mistake for broadcasters to go all-in on ATSC 3.0 deployment in 2021 when 5G is real and is already starting to be deployed. Right now, it looks like 5G deployment is at least a year ahead of ATSC 3.0 deployment.

I don't think anyone is thinking "Let's scrap ATSC 3.0 and hold off a few years while we develop ATSC 4.0!" Rather, I'm wonder if it would be feasible over the next couple of years for broadcasters and the FCC to settle on some implementation of 5G (perhaps incorporating AWARN plus FeMBMS multicast video) as a potentially superior alternative to ATSC 3.0 for transmission of free OTA TV and public alerts, plus whatever other business opportunities that broadcasters can find for their licensed spectrum.

Realistically, probably not. Given how far along ATSC 3.0 is, and the degree of support it has from Sinclair and (to a bit lesser extent, perhaps) Nexstar, ATSC 3.0 will probably have to succeed or fail on its own merits. But if it fails, maybe it takes until, say, 2024 for the industry to collectively say, "Yeah, this isn't catching on and working out for us, now what?" That's a lot of precious time and money wasted.
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post #2126 of 2258 Old 09-10-2019, 03:59 PM - Thread Starter
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5G downlinks and ATSC 3.0 are both Cyclic Prefix OFDM. At the lowest layer, they are fundamentally the same thing. But the OFDM parameters have been chosen differently for each system.

For less than 6 GHz 5G (and 4G LTE), the OFDM subcarrier spacing is 15 kHz. This wide spacing was chosen so that large Doppler shifts can be tolerated. In other words, it's tuned for mobile.

For ATSC 3.0, the subcarrier spacing is 844, 422 or 211 Hz depending on the FFT size. The narrow spacing was chosen to maximize spectral efficiency. In other words, it's tuned for fixed receivers.

For the primary mission of broadcasting to fixed receivers, ATSC 3.0 is the better choice.

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post #2127 of 2258 Old 09-14-2019, 07:39 PM
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rabbitears.info


Has it listed this way
DC- Digital Channel
Phc- Physical Channel




Channel 2 in Atlanta


DC-2.1,2.2,2.3 Phc 32.1,32.2,32.3
DC-2.7,2.8,2.9 Phc 46.1,46.2,46.3
A Total of 6 channels 3 of those for the future.





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post #2128 of 2258 Old 09-15-2019, 07:52 AM
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Quote:
Originally Posted by MarkB64 View Post
DC-2.1,2.2,2.3 Phc 32.1,32.2,32.3
DC-2.7,2.8,2.9 Phc 46.1,46.2,46.3
A Total of 6 channels 3 of those for the future.
I'm not sure what you're getting at w/r/t ATSC 3.0. WSB's Gainesville translator operates on RF 46. The 2.7, 2.8, 2.9 virtual channel numbering is likely there so tuners in overlapping coverage areas don't trainwreck. Some tuners don't handle identical virtual channel numbers well.

I highly doubt they'd light up that translator for ATSC 3.0 as it doesn't cover much of metro Atlanta and would leave the ATSC 1 viewers it currently serves without WSB programming.

-=-=-=-=-=-=-=-=-=-=-=-

FWIW, and to make it easier to read, some conventions we'd prefer you use when discussing OTA:

1) Call letters. "WSB," not "Channel 2 in Atlanta." Call letters tell us everything.
2) Virtual Channel or VC. DC to most of us means direct current or District of Columbia.
3) RF over Physical Channel. WSB, Atlanta: VC 2, RF 32.

Much thanks.
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post #2129 of 2258 Old 09-17-2019, 06:13 PM
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Can anyone with more knowledge than I have of the relevant legal and market forces at play comment on the plausibility of the following scenario?

Sinclair and the Pearl consortium (basically, Nexstar and every broadcast group other than Sinclair) jointly create a software/operating system platform for ATSC 3.0 in the USA. All ATSC 3.0 tuners and their front-end software which accesses and displays their content must license this software platform. (Is that legal?) This software would use a common set of UI/UX conventions which all ATSC 3.0 stations would conform to. It would provide the framework for consumers opting into internet-enabled content and services, including the insertion of targeted ads, viewership measurement, etc.

Without the consumer connecting the tuner to the internet and opting into targeted advertising, all 3.0 tuners would be restricted to simply live viewing of free OTA linear channels. But taking those optional steps would unlock the ability to pause and rewind live TV (using a small amount of flash storage on board the tuner), expand the free program guide from the next 14 hours to the next 14 days, and let viewers connect their own storage (e.g. USB hard drive) for free OTA DVR service. However, due to DRM within the broadcast signals, viewers would not be able to FF past ads in their recordings. In fact, the ads displayed during playback would be targeted ads that stream in via the internet rather than whatever might have been displayed in the original main broadcast signal. Beyond that, consumers would be given the option to play certain ad-supported free on-demand content too (both local content such as newscasts and weather forecasts as well as the kind of stuff that appears on Tubi, The Roku Channel, etc.). Consumers might also have the option of paying to subscribe to pay TV services too, using a common storefront and payment system.

One standard app backed by the broadcasters would be available for all popular streaming devices (e.g. Roku, Fire TV, Apple TV, iOS, Android, etc.) to use as a front-end for ATSC 3.0 tuners for live and recorded content. That app would be the only way to watch ATSC 3.0 content on those devices. Perhaps the broadcast group would work with major TV manufacturers to allow them to customize the software UI a bit (e.g. fonts, colors, iconography, etc.) to blend in as part of with their smart TV's pre-loaded default software platform (e.g. LG's webOS) as opposed to simply using the same standard app deployed on streaming devices.
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post #2130 of 2258 Old 09-17-2019, 06:36 PM
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Sounds like a real PITA.

I bet a lot of people would skip ATSC 3.0 even if there was a lot of 4K HDR content, rather than being forced to watch ads.

Or they might spend a few bucks for a streaming service instead, which will also be 4K HDR and won't have the ads, such as Disney +.
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