How do I connect video?

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jpark37
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How do I connect video?

Post by jpark37 » Sun Aug 19, 2018 9:02 pm

Hello. I'm new to oscilloscopes, and trying to figure out what I need to hook up some old video game consoles. I'm interested in doing some real-time decoding experiments like http://codeandlife.com/2012/10/09/compo ... -practice/ for composite NTSC, RGBS, and maybe component.

I purchased a 5444D. (Although in hindsight, I probably should have asked what would be best.) I have RCA -> BNC 75 ohm cables and terminators already. Is it just a matter of getting a 75 ohm tee adapter like this one? pasternack.com/bnc-female-male-female-tee-adapter-pe9365-p.aspx

I've been seeing around that 50 ohm is more standard for oscilloscopes, so I'm not sure what the correct combination of components looks like.

Thanks,
James

bennog
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Re: How do I connect video?

Post by bennog » Mon Aug 20, 2018 8:18 am

Have you looked at

Always wanted to try this for myself (if I had more time) :(

topic13543.html
topic11185.html

and

http://codeandlife.com/2012/07/31/realt ... picoscope/

Benno

jpark37
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Re: How do I connect video?

Post by jpark37 » Tue Aug 21, 2018 4:40 am

Those links don't seem to answer my question. From what I've read, I don't think it's valid to use an RCA/BNC 75 ohm cable directly into the oscilloscope. Maybe the cable + T adapter + terminator? But does a 75 ohm T adapter work with the oscilloscope? Once I get past these obstacles and get access to the voltage samples, then I can start to have some fun. :)

Gerry
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Re: How do I connect video?

Post by Gerry » Wed Aug 22, 2018 6:16 pm

Hi James,

Ideally you would just use a 75 ohm feed-through terminator so that, when considered as a transmission line, the cable is terminated in it's characteristic impedance (so that there are no reflections at a discontinuity between 75 ohms and 50 ohms that can corrupt the signal, e.g. distorting and lengthening of fast edges).

Regards,

Gerry
Gerry
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