video and digital on the same coax cable

[kender]

I know it’s possible to send video up a coax and digial (9600 baud or so) signals the other way. But what’s the quickest way to make such system work? Are there pitfalls?

Thanks,
Nick

 

[brmadhukar]

There are new standards on Coax which do this seamlessly.

Your proposal works because data and videa are at two different frequencies. I cant see any issue other than DC isolation.

hope this helps

 

[IanP]

You can transmit baseband video over a coax cable and using two RF-chokes at both ends as separators "inject" in between modulated (433MHz or somehing like that) data ..
I wouldn't do it the other way around, as video is "amplitude" sensitive ..

Rgards,
IanP

 

[kender]

Ian, thanks for the schematic! I suppose, modulate my digital signal by simply ANDing it with a high-frequency clock.

What's the best way to inject the modulated digital into the cable without disrupting the impdance match?

 

[IanP]

I would't do ANDing - the output signal will still have "low frequency" data component ..
Why not to use off-the-shelf "el-cheapo" 433MHz data modules?
Something like ZW3100 and ZW3102:
https://www.electusdistribution.com.au/productResults.asp?form=CAT&CATID=31&SUBCATID=109
All what you need to do is to connect them to coax through 15pF caps (or 10nH inductors) to match 75Ω impedance of the coax ..

Regards,
IanP