# Analog and digital UHF over the same line?



## houstonmat (Jan 12, 2007)

I have an lcd tv that has both NTSC and ATSC tuners. It is in a part of my home that only has a single coax cable available (shame on me for not running two when I had the walls torn out!!). 

My question is this: can I use that single coax cable, split it at the TV--one for the NTSC tuner (I have analog cable TV) and one for the ATSC tuner? 

Ideally, I'd like to place my UHF antenna outside where the analog cable comes into my house and have both the signals go to the tv over the single coax. 

Is this possible? Currently I have a Radio Shack DA-5200 that works phenominally well in my zip code (77006). 

Thanks much for your help!!!


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## HIPAR (May 15, 2005)

There will be some power loss in the splitter but if the signal is strong enough I'm betting it will work. Try it.

--- CHAS


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## Cholly (Mar 22, 2004)

With goood quality splitters at the point of entry to the house and at the receiver, you'll experience a 6 to 8 db. signal loss This could be a bit of a problem, but I'd be inclined to agree that it's doable. You didn't state whether the cable was RG-59 or RG-6. If it's RG-59, you can expect some additional loss.


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## KML-224 (Nov 9, 2006)

I have analog cable coming into my room now in New Britain, CT (southwest of Hartford). Just before the back of the TV, I have a splitter, with one line continuing to the "VHF/UHF/CATV" jack and the second line going to the "DIGITAL ANTENNA IN" jack (both 75 ohm cable connections). Any non-premium cable channel from 2 to 99 comes in as usual. Once the TV is in digital tuner mode (look for 3-1, 8-1, etc.), I do a digital cable scan. The downside is that it can sometimes take as long as 10 minutes. The up side? Since it's a QAM tuner, I get the occasional movie feed, PBS-HD at night, NBC Weather Plus, The Tube, and the primary digital channel of local ABC, CBS, FOX, NBC and CW. [WCTX-DT, the local My affiliate is available in HD, but I have to get that on antenna.]


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## kenglish (Oct 2, 2004)

He's saying he has analog Cable TV and want's to combine it with OTA Digital TV. That's not gonna work, because they are overlapping frequencies...plus, you don't wanna broadcast pay cable to your non-subscribing neighbors!

Might want to find some type of an A/B switch, and put it back where the single-cable begins. Wonder if anyone makes a remote controlled one that works thru walls (not IR, but RF remote)? Radio Shack has sold an IR controlled A/B switch, you might have to use an IR Extender with it, though.


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## Cholly (Mar 22, 2004)

Oops -- my bad! This could indeed be a problem, since cable channels 65 - 94 occupy the same part of the frequency spectrum as the UHF broadcast band. Since the analog cable is continuous from outside the house to the set, an A-B switch seems to be ruled out. Best bet: run a separate cable for the UHF antenna.


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## houstonmat (Jan 12, 2007)

Well I've run experiment #1 with mixed results. Upstream of my coax I put a UHF/VHF signal combiner. On the VHF I hooked up my analog cable line in and on te VHF I hooked up my UHF antenna. At my tv, I placed a UHF/VHF splitter and sent VHF to my tv's NTSC tuner and VHF to my signal amp (the one that came with the aforementioned Radio Shack antenna) then to my ATSC tuner on my tv. I didn't have any help so antenna placement testing wasn't easy, but I definitely got a digital signal for channel 2. On my analog cable channels, some were absent completely, some were audio only but none had a picture. Any ideas? This was very much a shot in the dark with no expectation of positive results, but now it seems like I'm getting close...maybe.


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## kenglish (Oct 2, 2004)

Not a good idea. There won't be much isolation between the CATV signal line and the antenna, so you'll be broadcasting cable tv over the air. FCC, FAA, etc frown upon that.


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## harsh (Jun 15, 2003)

What you're trying to do will not work for several of reasons:

1. There is overlap in station frequencies which will clobber lots of channels on both.
2. Your receiver must be set for either CATV mode or Antenna mode; you can't have both at the same time.
3. Not all ATSC stations are UHF.

For future reference, if you're talking about NTSC signals from your cable company, you should refer to them as CATV. Remember that cable also carries their so-called "Digital" (QAM) channels on the same wire so there is little or no space left over for injecting additional channels.


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## houstonmat (Jan 12, 2007)

Thanks to everyone for the information and help. This has been an interesting project. 

It seems that each of you was right--the frequency overlap and violation of FCC laws (and terms of service, I'm sure) proved too difficult to overcome. I may give it another go with a pair of A/B coax selectors in the near future, though that sure seems like a pain. 

One last question for you guys. In your experience, have you found that digital cable HD channels' quality are as good as OTA HD?

Thanks, all!


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## midwest_dxer (Dec 12, 2004)

kenglish said:


> He's saying he has analog Cable TV and want's to combine it with OTA Digital TV. That's not gonna work, because they are overlapping frequencies...plus, you don't wanna broadcast pay cable to your non-subscribing neighbors!
> 
> Might want to find some type of an A/B switch, and put it back where the single-cable begins. Wonder if anyone makes a remote controlled one that works thru walls (not IR, but RF remote)? Radio Shack has sold an IR controlled A/B switch, you might have to use an IR Extender with it, though.


Ok Ken,I'm gonna pick your brain here.Would there be an analog cable box he could insert close to the entry point that would output a composite signal signal,and then use a modulator to send all the analog cable channels up the coax on one frequency,then inject OTA on all the remaining frequencies? I understand it would have to be a UHF remote type box to be able to change cable channels.


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## harsh (Jun 15, 2003)

houstonmat said:


> One last question for you guys. In your experience, have you found that digital cable HD channels' quality are as good as OTA HD?


Not many here have much experience with digital cable, but from what I've seen, it can run the gamut. My local Comcast absolutely butchers 720p content. The 1080i content, typically reduced in resolution, looks much better than 720p, but still no comparison to OTA. Unfortunately this seems to go for the SD content too.

What you get depends on how your cable company gets their feed. Your mileage _will_ vary. At best, the content is being re-compressed and/or scales twice and sometimes three times .


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## harsh (Jun 15, 2003)

midwest_dxer said:


> Would there be an analog cable box he could insert close to the entry point that would output a composite signal signal,and then use a modulator to send all the analog cable channels up the coax on one frequency,then inject OTA on all the remaining frequencies? I understand it would have to be a UHF remote type box to be able to change cable channels.


Cable, unless you have a trap on it, is pretty much full to the brim. You would have to carefully notch out channels (probably in the UHF range) to make room for the OTA stuff. Each OTA channel would have to be translated to a frequency that was close (but not too close) to the others so you could shoehorn them in. This is typically pretty expensive gear that takes multiple channels and relocates them.

Suffice it to say, you should be looking for a TV with two RF inputs.


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## 4DThinker (Dec 17, 2006)

Diplex. I use diplexers in my attic to combine my DirecTV SAT cable with my OTA antenna feed on two SAT outputs of the switch they put in the attic, then another diplexer down in two bedrooms to break out the two signals. It works perfectly. Diplexers are NOT the same as splitters, although they look similar. It works best with RG-6 cable. There will be a little signal loss simply from the interruption of the continuous cable between the source and your TV. Give it a try.


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## houstonmat (Jan 12, 2007)

Can you include a link to the diplexer(s) you use? Thanks so much!


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## Cholly (Mar 22, 2004)

houstonmat said:


> One last question for you guys. In your experience, have you found that digital cable HD channels' quality are as good as OTA HD?
> 
> Thanks, all!


In my experience with Time Warner Cable in the Charlotte area, OTA is superior to cable HD. The cable companies resort to a certain amount of compression in order to deliver the signal to you.

Regarding Diplexers: they won't work in your case, since you are dealing with overlapping signal sourdes. They work with OTA and satellite because there is no overlap.


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## 4DThinker (Dec 17, 2006)

I use diplexers that were given to me by the DirecTV installer way back when I had a Hughes HDVR2 installed. They look like this: http://www.fadfusion.com/selection.php?product_item_number=20161200703

I also have an old Terk set that came with Terk antenna.

However, Charlie is right. I didn't pay enough attention to your first post. All the Diplexers I can find on the web state specifically on them that they are for SAT inputs on one side and cable/ant on the other. It doesn't look like you can put the cable input on one side and your antenna input on the other.

As for adding another cable.. Do you have attic access to the top of the wall where your current cable comes into the room? I've personally had luck taping/stapling two cables to the current cable, then pulling them all back into the attic. In my case the old cables dropped simply straight down into the interior walls where there was no insulation and no firebreaks. I'd hook up the two new cable up in the attic, and get a new plate for the box with two F-connectors. Label them to keep track of which it which (cable/ant).

I've also simply added a new open-backed box to the wall just above the existing F-connector box, then dropped a new cable down until I could fish it into the new box. It's a good opportunity to drop a phone and/or network line too, and you can find plates to mount jacks for them all.

Good luck.


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