X10 Video/Audio Distribution quality - AVS Forum
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post #1 of 12 Old 06-26-2001, 08:39 AM - Thread Starter
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I just recently received X10's Entertainment Anywhere (also goes under the name DVD Anywhere, etc). http://www.x10.com/products/x10_vk57a.htm

Basically, it sends composite video and stereo audio via 2.4GHz through walls and such. I only need to send it about 20 feet, but through 2 walls.

The problem is, the video quality really stinks. Even when the sender and receiver are close to each other, I get ghosting in areas of high contrast, making things like The Simpsons (and the menus on my TiVo) look very fuzzy. Anybody know what would cause this type of ghosting (input signal not strong enough, too strong, etc)? Is there any type of filter or amplifier I could stick on either end to improve the audio quality? The unit cost me next to nothing ($20 off the regular $70 price, plus an extra $30 gift certificate that I used on an IR extender). So if I'd return it, I'd only get $20 back, minus whatever I'd have to spend on shipping. So I'm looking to improve the quality, or perhaps just use it for audio. The audio quality seems to be fine, though I have to admit I haven't really cranked it.

The Cat5 s-video distribution thread here reminded me that I have 2 pairs of Cat5 running between the two rooms not being used (the other 2 pairs are being used for 10-baseT). Perhaps I could just split those two pairs off and run the video via Cat5. Is there any problem with splitting S-Video (not using an expensive amp or anything)?
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post #2 of 12 Old 06-26-2001, 06:04 PM
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I've never seen a wirless video distribution system that didn't really stink to high heaven. The problem is that broadcasting and receiving a video signal is something you just can't do with a couple of hundred dollars of hardware.

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[This message has been edited by work permit (edited 06-26-2001).]

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post #3 of 12 Old 06-27-2001, 06:02 AM
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Workpermit, what would you recommend then ??
I only need a decent picture on my bedroom small TV to watch satellite tv programs ! Is this X10 system really that bad ?
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post #4 of 12 Old 06-27-2001, 06:24 AM - Thread Starter
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Greg - I'll post some screenshots later today and you can see for yourself.
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post #5 of 12 Old 06-27-2001, 07:35 PM
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Here's someting that might work http://www.avsforum.com/ubb/smile.gif http://www.viscountvideo.com/dynapix.htm

Only kidding

I bite the bullet and use wires. There's an interesting thread on using shielded cat 5, The "normal" route is rg59 or rg6 cable. There maybe a good wireless solution out there, just eveyting I've seen looks bad

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post #6 of 12 Old 06-28-2001, 10:59 AM - Thread Starter
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Well, I went ahead and wired the S-Video over Cat-5, inspired by the other thread. I just wired it directly, making sure the signal/ground were pairs in the Cat5. Worked great - quality was specatular. Then, the next day I fired it up and I saw scrolling diagnal lines - waves really, through the picture. I could swear they weren't there when I first set it up, but I guess it was late. I tried to figure out if it was interference from something else, but I could find nothing.

The wiring is like this:
Code:
TiVo Output             TV-Input
   |------Svideo cable----|
      |
      |Cat 5, spliced into the SVideo cable
      |
      |(pins 4,5,7,8)
    Modified RJ45 splitter  --(pins 1-8)--35' Cat5 cable----------to other room, similar demuxer setup.
      |(pins 1,2,3,6)
      |
   Ethernet Hub
The scrolling is faintly visible on the TV connected directly with the Svideo cable, unless I unplug the spliced connection. So something is inducing interference onto that long Cat5 cable. I have tried disconnecting the ethernet side of things, so that only SVideo is running over the cable, with the same results.

Looks like I need some sort of S-video distribution amplifier. Anyone know where I can get one fairly cheap?

This is turning into more of a project than I originally bargained for.


[This message has been edited by Saturn49 (edited 06-28-2001).]

[This message has been edited by Saturn49 (edited 06-28-2001).]
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post #7 of 12 Old 06-28-2001, 02:04 PM
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One problem that immediatley comes to mind is the impedence mismatch between your cat 5 cable and svideo in/out. Unshielded Cat 5 cable has a charactersitic imedence of 100 ohms. Audio/video cables, rg6/rg59 coax cables, and shielded Cat 5 have a characteristic impedence of 75 ohms. Ideally, you need to either rn 75 ohm cable, or use an "impedence transformer", which for these applications is called a "balun". Something like this: http://www.infinity-cable.com/icp_balun_svideo.htm

I've never done this, these are just my thoughts.


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post #8 of 12 Old 06-28-2001, 09:40 PM - Thread Starter
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I KNEW I wasn't going nuts. The wavy line problem has resolved itself. I am in an apartment - the top half of an old house - something must be causing intermittent interference, perhaps from the residents downstairs.

Greg, and anyone else interested, I have posted some screenshots of the x10 composite video vs. the svideo over cat5 w/o interference:
http://www.athenet.net/~saturn/x10.jpg

and
http://www.athenet.net/~saturn/good.jpg

I will post a bad.jpg as soon as the interference appears again.

Greg: I can post screenshots of actual programs too, if you'd like to see how bad the X10 really is. The TiVo menus just accentuate it.


Alex: I realize the impedence is wrong, but the cheap s-video over cat5 wall mount devices mentioned in the other thread couldn't have had a balun in them, considering their price. So I thought, what the heck, it just may work, and it has to be better than the X10...

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post #9 of 12 Old 06-28-2001, 11:54 PM
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I'm new to this Cat 5 cable stuff ! I will be checking on the other thread, but for now am I correct to assume that if I want to have something decent on my 2nd floor bedroom, that I should have this cable running from my living room (my dvd source) to my bedroom TV ? You are right to point out that the X10 is not that great.
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post #10 of 12 Old 06-29-2001, 07:04 AM
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I can easily beleive that regular cat 5 cabling run directly from the video source to the TV would be subject to noise. Remember, you are using UNSHIELDED cat 5 cable.
Unshielded cat 5 cable is meant to be run with "balanced" transmitters & receivers.

A balanced transmitter sends a positive signal down one wire in a pair and a negative version of it down the second wire. On the receive side, you take the difference between the two wires in the pair as output. By taking the difference, you tend to cancel out a lot of noise the cable picks up. Cat 5 computer nic cards use this approach.

Most audio/video equipment uses unbalanced. This is when one wire carries the signal and the other wire is ground. Unbalanced transmission is meant to be carried on shielded cables.

I was being a little to quick in describing to you what a balun is. A balun is a "balanced/unbalanced" converter. It converts your "unbalanced" video signal coming out of your video source to a "balanced" one that is more immune to noise when sent over regular cat 5 cable.

If you want to run unbalanced signals on cat 5, you want some sort of shielding to reduce interference. The thread I saw was talking about video over just such a cable. If you want to run video over unshielded cable, I suspect you need to run a balanced signal.

If you're going to run a new cable, the "safe" way would be to run a coxial type cable for the video, plus something for audio.

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post #11 of 12 Old 06-29-2001, 04:39 PM - Thread Starter
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Well, the interference is back. Here's a screenshot of what it looks like. S-video over unshielded, unbaluned cat-5, with interference from *something*. I'll find it eventually, or maybe it'll disappear when the ladies downstairs move out in August...:-)
http://www.athenet.net/~saturn/bad.jpg

It actually doesn't look that bad compared to the good.jpg, but since those interference lines move, it is REALLY annoying. Again, anyone have any idea what common household appliance or device could cause such an interference pattern?

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post #12 of 12 Old 06-29-2001, 04:59 PM
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You can start with air conditioners, refrigerators, lamp dimmers, hair dryers, florescent lights...

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