# Digital Subchannels



## demsd (Oct 14, 2010)

Does anyone know if there is a limit on how many digital subchannels an LPTV station can have?


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## philtec (Sep 11, 2011)

Some in my city have 5.
DTV only retransmits only ONE subchannel of one station out of more than 15+ channels that have been transmiting subchannels since the beginning of digital transmisions.


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## Davenlr (Sep 16, 2006)

I have seen 6 SD used, and I have seen one 1080i and one 720p HD used.
I dont know if the FCC has a limit, but technically, 6 would be about the limit before the picture becomes unwatchable.


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## KyL416 (Nov 11, 2005)

An LPTV station is no different to a full power station when it comes how much bandwidth they have, the only difference is how far their signal goes. All of them have 18mbps, it's up to the individual station on how they divide it.

One of my local stations has 7 SD channels and 2 audio only channels, all various ethnic programming.
http://www.wmbctv.com/

Los Angeles is even greater when it comes to their ethnic stations:
KSCI has 9, KJLA has 10 and KBEH has 8

Most of them use stat muxing with a variable bitrate, they are watchable, but these stations serve a niche for the various ethnic communities and have no plan to upgrade to HD since the source of their programming are usually foreign and aren't available in HD anyway.


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## demsd (Oct 14, 2010)

That many, wow. Most stations in my area have 2 with some having 3. Since I have not seen one with more then 3 I thought there may be some restrictions on the number of subchannels. Most have nothing [worth watching] on their subchannels, while others utilize them for additional revenue stream with affiliate programming from This TV, Antenna TV, etc.



KyL416 said:


> ... but these stations serve a niche for the various ethnic communities and have no plan to upgrade to HD since the source of their programming are usually foreign and aren't available in HD anyway.


Isn't the move to digital by 2015 an FCC requirement?


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## James Long (Apr 17, 2003)

demsd said:


> Isn't the move to digital by 2015 an FCC requirement?


Digital does not require HD.


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## demsd (Oct 14, 2010)

Learn something new every day.

Thanks.


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## fluffybear (Jun 19, 2004)

KyL416 said:


> Los Angeles is even greater when it comes to their ethnic stations:
> KSCI has 9, KJLA has 10 and KBEH has 8


I believe all 3 of those are Full power stations though.

While KSCI does offer 9, KJLA is currently only offering 6 (57.3, 57.6, 57.7 are dark) and KBEH are not offering any sub-channels.

WANN here in Atlanta is a low power station and offers a Program Guide, 9 video signals and 6 audio (simulcast of atlanta radio stations)..


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## harsh (Jun 15, 2003)

demsd said:


> Isn't the move to digital by 2015 an FCC requirement?


September 1, 2015.


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## Hoosier205 (Sep 3, 2007)

Even one is one too many.


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## KyL416 (Nov 11, 2005)

fluffybear said:


> I believe all 3 of those are Full power stations though.


As I said there's no difference between a full power station and a low power station when it comes to bandwidth, all of them have 18mbps. The only difference is how far the signal goes.


Hoosier205 said:


> Even one is one too many.


Yeah for an HD channel it is, but for stations that air nothing but ethnic programming or are part of a network that isn't even available in HD, if they don't add any additional subchannels, they either go overkill and have 18mbps devoted to one SD feed or only use about 2-8mbps and have the rest in a null packet doing nothing.
Here's an example of how much bandwidth WMUN-CD in NYC is dumping in the null packet since they only have one SD channel:
http://www.rabbitears.info/screencaps/ny-nyc/73207-0_0.htm


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## demsd (Oct 14, 2010)

Hoosier205 said:


> Even one is one too many.


How is that?

With pay TV rates what they are, and what they are bound to be, and with a stagnating subscriber rate, OTA is actually getting popular again. The number of OTA antenna's sold last year doubled that of 2011.


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## demsd (Oct 14, 2010)

harsh said:


> September 1, 2015.


Right [I never mentioned HD, only digital].


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## Hoosier205 (Sep 3, 2007)

demsd;3169012 said:


> How is that?
> 
> With pay TV rates what they are, and what they are bound to be, and with a stagnating subscriber rate, OTA is actually getting popular again. The number of OTA antenna's sold last year doubled that of 2011.


Bitrate. More subchannels leads to less bitrate for the main channel. Even with advances in compression techniques and technologies, subchannels reduce the potential quality of main channels.


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## demsd (Oct 14, 2010)

Its free TV. You don't pay much, you don't get much.


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## Jon Ellis (Dec 28, 2003)

There's a mention in another thread on this forum of a station in San Francisco with 12 or 14 channels. I believe, theoretically, you could have up to 99 channels, but most would have to be audio-only since you wouldn't be able to squeeze 99 video signals into 18 mbps!

I know the HD purists hate this idea, but if you're a station that's not affiliated with an HD network and you don't run any first-run syndicated programming, it's really just a waste of bandwidth to put out an "HD" signal since none of the programming is really in HD. In many cases it could make more business sense to offer 9 SD channels, if you have a master control facility that can insert commercials and handle EAS on that many channels. Or, it could make sense if you're in a rural area with few stations.

Keep in mind some stations "fake" it a bit - the FCC says if you have two stations in a market, you can have both of them remap to the same channel. In Minneapolis, channel "2" is actually a combination of RF 23 and 34 and channel "5" is a combination of RF 35 and 45. (To make it more confusing, there is also a "23" that actually comes from RF 22.)


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