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PostPosted: Wed Mar 04, 2009 3:10 pm 
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We only have analog cable (channels 4-99) service since comcast's digital service requires one to rent a box for each TV. I ran a new coax line to where the cable line comes into our house. This line is connected to the HDTV. Here's what I don't understand: the HDTV is able to view the analog cable just fine. It is also able to pickup about 8 digital over the air channels but only if I disconnect the coax from the wall (i.e. the coax cable just dangles from the back of the TV). If I reconnect it to the wall coax jack so the analog cable is available, it no longer received the digital over the air channels at all.

Is this normal? Is there some sort of filter on my cable line that would account for this? How are other folks out there using the HDTV's to watch their cable and their local OTA digital stuff?

Thanks!

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PostPosted: Wed Mar 04, 2009 3:18 pm 
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Location: Virginia, USA
What make/model of TV? I guess it's possible that your TV segregates analog tuning from digital tuning, so that when you're analog (cable is connected to the back of your TV) you only seem to get analog channels, and when you're getting OTA signals (letting your coax cable serve as a very poorly designed antenna by leaving it connected to the TV but not to Comcast), it only shows you OTA channels.

Keep in mind that Comcast is required (I am pretty sure) to carry local digital channels in the clear via QAM. Your TV tuner would have to support tuning via QAM, and you'd be in the same boat as above, I imagine--your TV may not let you watch both the analog channels and the QAM channels at the same time.


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PostPosted: Wed Mar 04, 2009 4:08 pm 
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Thanks for the reply. It's a Samsung LN22450A. You are right: I am able to get the DTV channels while in "cable" mode. I just kinda pisses me off that I can't switch modes and get the OTA channels and that I have to watch them potentially transcoded to a lower quality through my cable.

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PostPosted: Wed Mar 04, 2009 4:39 pm 
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I found the manuals for your TV and am downloading them now from Samsung (it's the 22A450, BTW... that threw me for a while).

I guess the problem is the following: you have to scan for channels either "over-the-air" or using a cable TV standard. It assumes you have EITHER an antenna OR a cable connection. I'm not sure there's any way to let it know you want to have BOTH (in other words, you want your analog cable channels PLUS you want over-the-air channels). Frankly, I'm not sure there's any TV that can be set up like that, since I can't think of a good way of running both an antenna AND a cable connection into the back of a TV.

If I were you, I'd use the cable connection and get your analog channels (for as long as they last... most cable providers are going to eventually get rid of them if they haven't already) as well as the clear QAM HD channels. Given your TV size it's unlikely that you'd notice any quality difference unless you were a few inches away, and as it is, there's a thread on the board here somewhere that says there is little or no reduction in quality nowadays with Comcast's rebroadcasting of the local HD channels.

And, of course, if you really want the over-the-air signals, get a nice ATSC tuner and a big hard drive for your MythTV box and record away!


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PostPosted: Wed Mar 04, 2009 11:09 pm 
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ceenvee703 wrote:
I'm not sure there's any way to let it know you want to have BOTH (in other words, you want your analog cable channels PLUS you want over-the-air channels). Frankly, I'm not sure there's any TV that can be set up like that, since I can't think of a good way of running both an antenna AND a cable connection into the back of a TV.


FWIW, my 3-year old 50" Samsung DLP had two coax connectors and was able to deal with both OTA & cable. The new 50" Samsung Plasma I just purchased a few months ago does not.

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PostPosted: Wed Mar 04, 2009 11:30 pm 
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marc.aronson wrote:
FWIW, my 3-year old 50" Samsung DLP had two coax connectors and was able to deal with both OTA & cable. The new 50" Samsung Plasma I just purchased a few months ago does not.


Same here -- RCA DLP had two coax connectors, my new Sharp LCD doesn't. Seems like a step backwards to save the company what -- 12 cents a unit?

I had my antenna set up, but I just plugged in my analog cable instead and let it scan for digital stations. Found my locals in HD as clear QAM. Doesn't look as good as OTA, but it's more reliable.


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PostPosted: Thu Mar 05, 2009 8:37 am 
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marc.aronson wrote:
FWIW, my 3-year old 50" Samsung DLP had two coax connectors and was able to deal with both OTA & cable.


I bet many older sets (yeah, 3 years = older, sorry :) ) had multiple coax inputs specifically to allow for picture-in-picture (two inputs, two tuners). I know my 5-year-old Sharp LCD has two coax inputs to allow for POP (two side-by-side images).

Picture-in-picture is something that's mysteriously absent from HDTVs nowadays... is there not enough horsepower to do it, or some other technical reason?


Last edited by ceenvee703 on Thu Mar 05, 2009 12:24 pm, edited 1 time in total.


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PostPosted: Thu Mar 05, 2009 12:06 pm 
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graysky wrote:
Thanks for the reply. It's a Samsung LN22450A. You are right:
I am able to get the DTV channels while in "cable" mode. I just
kinda pisses me off that I can't switch modes and get the OTA
channels and that I have to watch them potentially transcoded
to a lower quality through my cable.

If you're in the US, FCC regulations require that cable
operators provide the local OTA channels without reducing their
quality. AFAIK, they're supposed be providing the exact same
MPEG program stream that the local broacasters are sending
them. That's not to say that your cable operator isn't
violating the regulations.

[This assumes that the local broacasters _are_ providing a
program stream to the cable operators -- they'd be have to be
insane not to.]

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PostPosted: Thu Mar 05, 2009 5:44 pm 
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Grant_Edwards wrote:
If you're in the US, FCC regulations require that cable
operators provide the local OTA channels without reducing their
quality. AFAIK, they're supposed be providing the exact same
MPEG program stream that the local broacasters are sending
them. That's not to say that your cable operator isn't
violating the regulations.

I don't believe this is the case. As long as the cable operators broadcast some semblance of the station, I do not believe there is any requirement of the "quality" or format of the broadcast. The cable stations, do NOT, in fact broadcast the same quality as OTA. They reduce the bandwidth in all cases that I have encountered or heard about. None broadcast the OTA signal unmodified over their cable systems.

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PostPosted: Thu Mar 05, 2009 6:56 pm 
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Liv2Cod wrote:
Grant_Edwards wrote:
If you're in the US, FCC regulations require that cable
operators provide the local OTA channels without reducing their
quality. AFAIK, they're supposed be providing the exact same
MPEG program stream that the local broacasters are sending
them. That's not to say that your cable operator isn't
violating the regulations.

I don't believe this is the case. As long as the cable
operators broadcast some semblance of the station, I do not
believe there is any requirement of the "quality" or format of
the broadcast. The cable stations, do NOT, in fact broadcast
the same quality as OTA. They reduce the bandwidth in all
cases that I have encountered or heard about. None broadcast
the OTA signal unmodified over their cable systems.

It looks like you're right. In 2007 Bush's FCC caved in to the
cable companies and once again screwed over the consumer by
revoking the quality requirments in the "must carry"
regulations:
http://www.betanews.com/article/FCC-Adopts-Compromise-on-MustCarry-Provisions-for-Cable-TV/1190236878

I missed that little bit of news.

All that's left is to change the letterhead to the "Federal
Comcast Corporation." :(

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PostPosted: Fri Mar 06, 2009 9:20 am 
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That's why I kicked Comcrap to the curb and dusted off the old rabbit ears.

No regrets.

Martian

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PostPosted: Fri Mar 06, 2009 10:19 am 
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Martian wrote:
That's why I kicked Comcrap to the curb and dusted off the old rabbit ears.

No regrets.

Same here. Quality on low-VHF channels was horrible, and the
dullards they would send out would check the "signal strength"
and declare it was fine.

In my case rabbit ears weren't good enough, so I had to order
an Antennas Direct DB2:

http://www.antennasdirect.com/DB2_Indoor_antenna.html

Add a Roku Netflix set-top box, and I the only things I'm
missing out on compared to cable service are the bad service
and the monthly bill.

My current problem is that the Zalman "Ultra Quiet" CPU cooler
in my FE/BE makes a _lot_ of noise. So, I'm working on
building a "diskless" FE out of a Mac Mini. Then I just have
to figure out where to park the BE box.

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PostPosted: Fri Mar 06, 2009 2:43 pm 
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Thanks for all the replies, all. Special thanks to ceenvee who took the time to d/l and read my TV's manual! Guess we're stuck with Comcast's re-encode of the OTA stuff until R6 gets finalized and mythtv-VDPAU becomes stable since the frontend machine needs VDPAU to display 720p h264/mpeg2 without dropping frames/sync problems.

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