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| video via powerline - modulating/demodulating video signals |
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| ACS:
I am 14 years old and visit the 9th class at a high school. I look for a diy solution to help my school. The goal of my project is to run a video signal over the powerline. My Idea is to amplitude modulate the analogue video signal with a carrier frequency in the high kHz or low MHz range. Then I will feed that modulated signal over the powerline, on the receiving side I want to filter out the 60hz mains voltages and feed a demodulator with the high frequency modulated signal. What I want is a simple modulator and demodulator, which I can give and receive a (composite) video signal. Can anyone help me by sharing some ideas or circuit’s? Thanks in advance for your assistance! |
| Marco:
Doing powerline data transfer legally is going to be hard. There are existing low frequency signalling protocols you don't want to be interfering with, the higher frequencies might emit EMI. Why not "just" use two raspberri PIs, an USB digitizer and two homeplugs? (Getting it all to work together still won't be entirely trivial.) |
| HB9EVI:
Not a very good idea to work on mains directly for a start. I'd maybe support that idea when transmitting a video signal broadband over a coax, but like that? no way. If it's a basic need to get the signal from one room/floor to another, I'd evaluate following points: - is the content to transmit really only available in analog; if the media it origins from is digital, then keep it digital for transmission. - if its origin is digital, use tcp/ip over wifi if there is no wired network; as a hamradio operator I don't encourage you to use powerline communication. - if the content is bare analog, convert it to digital und follow the ideas above. btw. to be more verbose wouldn't be a bad idea. What's the aim of that project? Is it a school project you have to complete or is it a technical problem the school faces for their duties. As a school project, I'd advise you something easier to start with; if it's a school matter, leave the fingers from it - if the school invests on a students agenda and something goes wrong or doesn't work, you're the one to blame - and from my own experience I tell you: that's not the position you want to be in. |
| soldar:
--- Quote from: ACS on June 10, 2019, 02:05:54 pm --- My Idea is to amplitude modulate the analogue video signal with a carrier frequency in the high kHz or low MHz range. --- End quote --- You got that backwards. You modulate the carrier with the signal. The most basic video signal is going to have a bandwidth of 4 - 5 MHz so you will need a carrier at least ten times that. The old lowest VHF channel 2 was 54 MHz. AM modulation of a VHF carrier is not rocket surgery but I do not think it is a beginner's project either. And I am not sure power-line is the best transmission medium. Over the air might go better. You say you are in Germany and you have 60 Hz Mainz? |
| HB9EVI:
technically over the air is certainly better, but not by the law. Self built transmitters are reserved to radio amateurs only. Even if there are ISM bands, self constructed devices are not allowed to be operated on those frequencies either. |
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