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post #451 of 601 (permalink) Old 2012-02-17, 04:20 PM
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I really doubt if they would re-design ATSC to support a 2 or 3 MHz channel when all they have to do is put multiple broadcasts on one 6MHz channel. Using the same standard with H.264 only requires new encoders and decoders (not that expensive actually). A new standard would require replacing the entire broadcast infrastructure.

The other thing that would help save spectrum is remapping the channel allotments to have transmitters in the same area use adjacent channels more often. With DTV, adjacent channel interference is not a big problem if the signal strengths are similar, but is a problem when one is much stronger than the other.

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post #452 of 601 (permalink) Old 2012-02-17, 08:14 PM
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RE: multiple channels sharing a single 6Mhz frequency


These are the only stations that I know of that currently share multiple major network channels using sub-channels,
a single antenna and single channel concept.
____________________________________

Channel: WICU Erie PA
SJL Broadcasting, Inc

Digital 12 (VHF)
Virtual 12 (PSIP)

12.1 NBC WICU HD
12.2 The CW SD
12.3 CBS WSEE SD
______________________________________

Channel: WSEE Erie PA
Lilly Broadcasting, LLC

Digital 16 (UHF)
Virtual 35 (PSIP)

35.1 CBS WSEE HD
35.2 The CW SD

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post #453 of 601 (permalink) Old 2012-02-17, 08:32 PM
 
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Here is a link to the article I was summarizing: http://www.tvnewscheck.com/article/2...victory/page/1

This is, indeed, a political victory for the NAB and broadcasters. Yes, there is a process for setting up auctions. However, the steps are complex, especially with having to have the repack plan in place first.

Also, the ATSC continues to evolve standards. Check out http://www.atsc.org/ to see what's being discussed.

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post #454 of 601 (permalink) Old 2012-02-17, 09:53 PM
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Thumbs up Mixed expectations!

I now seems that the 2009/2011 transition was just the stepping stone toward the possibilty of many interesting developments to come.

Spectrum evolution?
http://www.spectrumevolution.org/category/mission

Instead of creating another mixed bag of broadcast standards, a global broadcast standard is needed to ensure affordable equipment development & manufacturing. Neighboring borders would have to work together as one shared entity to ensure against spectrum co-channel issues.

We apparently are headed for some very interesting advancements in broadcast TV., but likely at a cost of having less OTA broadcast channels.

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post #455 of 601 (permalink) Old 2012-02-18, 12:23 AM
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Quote:
Originally Posted by ota_canuck View Post
These are the only stations that I know of that currently share multiple major network channels using sub-channels,
a single antenna and single channel concept.
And they are using H.264? I didn't think any broadcasters in the US were using it yet since no TVs support it yet. I know of lots of instances of more than one broadcaster using the same physical channel and MPEG.2. Some even have both in HD.

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post #456 of 601 (permalink) Old 2012-02-18, 12:38 AM
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if they were using h264, they'd be guaranteed lower ratings than a shortwave radio broadcast
maybe a pc based tuner could watch, be about it. so u know what that answer is.
I think Rochester has one station with two 720p Programs.

The wireless operators don't "need" anything. As it stands, to this day they still waste as much as they own.
They may "want", but there is a big difference between need and want.

With any luck, whatever process they come up with we can hope is so complicated noone will want anything to do with it.

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post #457 of 601 (permalink) Old 2012-02-18, 09:51 AM
 
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You can get the full picture of "dual HD" channels over at rabbitears.info. No broadcaster uses H.264.

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post #458 of 601 (permalink) Old 2012-02-18, 11:18 AM
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Quote:
Originally Posted by majortom View Post
if they were using h264, they'd be guaranteed lower ratings than a shortwave radio broadcast
maybe a pc based tuner could watch, be about it. so u know what that answer is.
Yes, that was kind of my point. What is currently being done doesn't prove that things can't be done differently in the future. AFAIK, most cases where two stations share one channel are affiliates where one "owner" owns two affiliate stations.

Currently the FCC licences a 6MHz channel to one "station' as that is all they could do with NTSC. With ATSC there is no reason they couldn't change the model to licence out a virtual sliver of that channel (in Mbits rather than MHz). It would then be up to the stations involved to either strictly enforce those limits or come up with a statmux agreement where they can borrow data packets from each other on an as needed basis.

While I agree that wireless operators don't have an urgent need for more bandwidth now, things will likely be different ten or twenty years down the road. now is the time to plan for that, so that evolutionary changes can be made rather than waiting until the last minute and springing a massive change on everyone.

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post #459 of 601 (permalink) Old 2012-02-18, 12:20 PM
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Frequency Sharing

I think there is more than a couple US stations that share the same frequency... Personally, I know of stations in Soo Michigan that share the same frequency, as well, I have snagged some New York State channels via tropo that also shared frequencies...

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post #460 of 601 (permalink) Old 2012-02-18, 12:40 PM
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Sharing transmitters amongs competing stations won't work with the current commerical scheme US and Canadian stations have, unless they go with the UK model of no stations broadcasting themselves, but a central broadcast authority or co-operative taking care of broadcasting with shared systems.

Option B is to allow individual stations to maintain their own transmitters, using a section of the 6 Mhz assigned to them.

The former could re-use most existing ATSC transmitting equioment, with just a change to encoders, to allow multiple 720P or 1080i channels per channel.
The latter would require new modulators as well, which can modulate a 1080i H.264 bitstream on 2 -3 Ghz of carrier.
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post #461 of 601 (permalink) Old 2012-02-18, 02:26 PM
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Extreme multi-channel configurations

Here's one station in Georgia that has 10 480i stations and 10 radio stations.
http://www.wanntv.com/
Obviously they must be using some type of compression or packet sharing techniques. With no psip/epg info as far as I can tell.

There is also a similar broadcaster in LA supporting 12 480i channels plus a few radio stations.

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post #462 of 601 (permalink) Old 2012-02-18, 02:39 PM
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KAXT-CD is the LA station with 12 channels.

KAXT-CD is using Statistical multiplexing: [or Statistical time division multiplexing]
http://en.wikipedia.org/wiki/Statistical_multiplexing

WANN in Georgia is likely using the same techniques.

I don't understand how they applied this method to work OTA?
http://searchnetworking.techtarget.com/definition/STDM

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post #463 of 601 (permalink) Old 2012-02-18, 07:30 PM
 
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From that article:
Quote:
The main statistics used in STDM are: each input device's peak data rates (in kbps, or kilobytes per second), and each device's duty factors (which is the percentage of time the device typically spends either transmitting or receiving data).
In this case, data rate for each subchannel is continually analyzed and adjusted to minimize artifacts. Of course, priority can be assigned in order to keep quality for one at the expense of others.

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post #464 of 601 (permalink) Old 2012-02-18, 07:47 PM
 
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Technically, stations are not sharing frequencies. Station A multiplexes station B's data to its stream and sends it out. There are several reasons why this happens in US markets.

First, there are markets, especially small ones, where there are not enough transmitters for all the networks. In the analog days stations would have secondary affiliations, and the programming from the secondary network would be shown at a different time. Now, a station can put their secondary network on a subchannel.

Second, co-owned stations sometimes back each other up with SD subchannels. This happened in LA and occurs in other markets, especially where one of the two stations doesn't quite cover the whole market.

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post #465 of 601 (permalink) Old 2012-02-18, 10:18 PM
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^^^there is also a third reason (though this is similar to your second one):

Third, better coverage for a LPTV/Class A station. An example of this is WWNY (CBS) and WNYF (FOX) in Watertown, NY are both owned by United Communications Corporation. WNYF is a Class A station but not only do they broadcast in HD on their primary channel, but also broadcast in SD as a sub-channel on WWNY's full power transmitter to get better coverage. Interestingly WNYF has a repeater in Massena - South Colton that only broadcasts in SD but also has WWNY in HD on a sub-channel.

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