Transmit Analog Video over long distance - Page 1
Forum section: electronics / projects

author: dustingrant
author_rank: Newbie
timestamp: March 27, 2019, 03:02:08 pm
content: Hello,I’m currently working on a project where I need to transmit analog video over approx 2000 meters through single conductor wireline. The project is a video camera that will be used to inspect boreholes. The camera is already built and runs on a 12 volt DC system, and consumes approx 0.5 amp current.Just wondering if someone could guide me in the right direction on how to go about doing this? I don’t know a lot about op amps but feel what I need to do for starters is amplify the signal before sending it up the line to surface. I would imagine it would pick up all sorts of noise and will likely have to filter the signal once at surface before running it to the TV.With the experience several people on this forum have, are there any tips anyone could give me? Thanks a lot!

author: MosherIV
author_rank: Super Contributor
timestamp: March 27, 2019, 03:09:56 pm
content: HiWelcome to the forum.You have 2 options:1 digitise the signal, transmit the digital stream, convert the digital stream back to analogue at the other end2 modulate your analogue signal at the camera end, transmit the modulated signal, demodulate at the other end.I do not have drop in solution for you. Research the 2 solutions I have suggested for yourself.Good luckEdit. I forgot to mention that you should research physical transmission hardware as well. Ethernet hardware is not suitable, 2km is beyond the workable distance. Try looking at telephany devices.

author: dzseki
author_rank: Frequent Contributor
timestamp: March 27, 2019, 03:30:45 pm
content: Get an RF modulator (from an old VHS video), apply the output to an RF power amplifier and there you have your own pirate TV station

author: coromonadalix
author_rank: Super Contributor
timestamp: March 27, 2019, 05:20:32 pm
content: we had a similar sytem, 4 video chanels up to 20 miles range, the hiccup it was a microwave dish antenna, you could not be in front of the antenna when it was working loll

author: Marco
author_rank: Super Contributor
timestamp: March 27, 2019, 05:52:25 pm
content: Googled it for ya ... given the very low -3dB bandwidth of your cable (~10 kHz) you'll need a specially adapted modem. It's possible to get high bitrate for video withrelatively high complexity modems, but most systems seem to work withrelatively low bitrate signalsand just accept very low update rates.It would be easier with a real coaxial cable rather rather than that single conductor monstrosity.

author: richard.cs
author_rank: Super Contributor
timestamp: March 27, 2019, 05:59:23 pm
content: You need to be a bit more specific, what is your video format exactly? Composite video? A camera datasheet would help here.Similarly what do you mean by "single conductor wireline" - coax? twisted pair? bellwire? wet string? Again, a datasheet for the cable would be good.Yes you almost certainly need to amplify it at the camera end as a minimum, though opamps are not a good choice here. It may also be sensible to modulate or otherwise manipulate the signal depending on the line characteristics.If itisa composite video signal sent over coax for example then you would be best modulating it onto an RF carrier, that moves your signal from 0-5 MHz to, say, 400-405 MHz so the signal is less dispersed (because the fractional bandwidth is less) and allows you to use the highly sensitive RF input on a standard unmodified TV.

author: Marco
author_rank: Super Contributor
timestamp: March 27, 2019, 06:38:33 pm
content: An armoured singe conductor wireline looks like it's only coaxial in the broadest sense, the paper says 10 kHz bandwidth ... trying to work with that in analogue is a fool's errand.

author: David Hess
author_rank: Super Contributor
timestamp: March 27, 2019, 07:10:46 pm
content: Linear Technology design note 92discusses the problem with baseband video over long cables.

author: Marco
author_rank: Super Contributor
timestamp: March 27, 2019, 07:20:53 pm
content: 10 kHz bandwidth ...

author: rhodges
author_rank: Frequent Contributor
timestamp: March 27, 2019, 07:22:40 pm
content: Borehole --- Camera --- Large screen TV --- 2km --- Telescope

author: pwlps
author_rank: Frequent Contributor
timestamp: March 27, 2019, 07:41:23 pm
content: From your post it is not clear for me : you want to develop your own electroniçcs or just want to find a circuit solving your problem? If you want to buy something ready to use I would suggest buying a pair of coder-decoder boxes transmitting your video signal via Ethernet. There are plenty of those, google for e.g. "IP video extender" or "VGA over IP".

author: Marco
author_rank: Super Contributor
timestamp: March 27, 2019, 07:45:35 pm
content: No, if he wants something ready to go he can buythis.An ethernet modem will do bugger all on a wireline.