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S-video & Stereo audio over CAT5?

R

Racer X

Jan 1, 1970
0
Hi All,

I'm looking to make a pair of adapters so I can transmit s-video and stereo
audio over CAT5, and I'm wondering if anyone has any circuit diagrams, or
links to similar projects

cheers,
 
M

Mac

Jan 1, 1970
0
Hi All,

I'm looking to make a pair of adapters so I can transmit s-video and stereo
audio over CAT5, and I'm wondering if anyone has any circuit diagrams, or
links to similar projects

cheers,

Sounds challenging. CAT 5 cable has 4 pairs. I believe s-video has three
signals, and stereo audio has 2. So the obvious solution of using 1 pair
per signal won't work.

Would you consider sending audio over its own cable?

If so, you could probably send the S-video over three pairs in one cable,
and up to 4 channels of audio on the other cable.

Next is the impedance mismatch problem. Cat 5 cable has a differential
impedance of about 100 Ohms. Video wants to see 75 Ohms. You can
use either a transformer (assuming the DC component of the video singal
doesn't matter.. I'm not sure about this) , or a video op-amp buffer to
match the impedance for the video signal. At the receiving end, you
probably need to convert back to 75 Ohms, which means another buffer or
transformer. Or maybe you can just put a 25 Ohm resistor in series with
the 75 Ohm load.

For the audio, you might get away with just sending it over the cable
without any matching. Or you could use a high current buffer at the
sending end and terminate at the receiving end with 100 Ohms.

You may get some crosstalk on the audio channels.

Good luck.

regards,
Mac
 
M

Michael A. Terrell

Jan 1, 1970
0
Mac said:
Sounds challenging. CAT 5 cable has 4 pairs. I believe s-video has three
signals, and stereo audio has 2. So the obvious solution of using 1 pair
per signal won't work.

Would you consider sending audio over its own cable?

If so, you could probably send the S-video over three pairs in one cable,
and up to 4 channels of audio on the other cable.

Next is the impedance mismatch problem. Cat 5 cable has a differential
impedance of about 100 Ohms. Video wants to see 75 Ohms. You can
use either a transformer (assuming the DC component of the video singal
doesn't matter.. I'm not sure about this) , or a video op-amp buffer to
match the impedance for the video signal. At the receiving end, you
probably need to convert back to 75 Ohms, which means another buffer or
transformer. Or maybe you can just put a 25 Ohm resistor in series with
the 75 Ohm load.

For the audio, you might get away with just sending it over the cable
without any matching. Or you could use a high current buffer at the
sending end and terminate at the receiving end with 100 Ohms.

You may get some crosstalk on the audio channels.

Good luck.

regards,
Mac

"S-Video" is two signals. Luminance(+sync) and Chroma. You would need a
pair of video to CAT5 converters at each end of the cable. There are ICs
made to convert video to balanced, and back. Its easy to convert the
audio with a couple op amps per channel, per end.
--
8 days!


Michael A. Terrell
Central Florida
 
M

Mac

Jan 1, 1970
0
Sounds challenging. CAT 5 cable has 4 pairs. I believe s-video has three
signals, and stereo audio has 2. So the obvious solution of using 1 pair
per signal won't work.

As it turns out, I was wrong about this. S-video only has two distinct
signals, so you could get S-video and audio on a single run of Cat 5
cable. Follow Kim's link elsewhere in this thread for a canned solution.
Would you consider sending audio over its own cable?

If so, you could probably send the S-video over three pairs in one cable,
and up to 4 channels of audio on the other cable.

Next is the impedance mismatch problem. Cat 5 cable has a differential
impedance of about 100 Ohms. Video wants to see 75 Ohms. You can
use either a transformer (assuming the DC component of the video singal
doesn't matter.. I'm not sure about this) , or a video op-amp buffer to
match the impedance for the video signal. At the receiving end, you
probably need to convert back to 75 Ohms, which means another buffer or
transformer. Or maybe you can just put a 25 Ohm resistor in series with
the 75 Ohm load.

For the audio, you might get away with just sending it over the cable
without any matching. Or you could use a high current buffer at the
sending end and terminate at the receiving end with 100 Ohms.

You may get some crosstalk on the audio channels.

Good luck.

regards,
Mac

Mac
 
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