transmitting video through ac trasmission line

[grimarcher]

im a newbie in the group and i wish to know whether it would be possible to send video signal thru ac transmission lines...
i saw a similar project however they send fm signals thru the lines... they made use of intercoms...
i just want to know if video signals would be possible as well... thanks

 

[stevez]

I suspect that you are describing systems where a radio frequency transmitting device is coupled to the AC power lines - the radio frequency being modulated to carry the information. A receiver that is responsive to the RF (and not the AC, noise, etc) is connected to or placed nearby where it recieve the signal, much as a radio or TV would and demodulates it to extract the information - music, picture, data, etc.

To simply couple video information to the AC power line is possible but it would seem that the receiver would not be able to sort out the video from all the rest of the electrical energy.

 

[laroche73]

video over ac

I'm not familiar with the bandwidth limitations of power lines, but I think transmitting/receiving an analog NTSC video signal over them would be a tall order. Power line data transmission systems have to deal with a great deal of noise from many sources, and this impacts bandwidth.

You may have more luck with one of the various power-line (kind of like a modem that hooks up to your power line) or phone-line data transmission systems that sprung up during the 90's. I recently got a few surplus HomePNA cards for a few bucks each that are meant to network home computers over the phone lines (haven't tried them out yet, so I can't give you a thumbs up/down), and I believe there are similar devices that work over AC lines. You would have to convert video into a digital format and back, but then you could take advantage of video compression technologies like MPEG to make the most of the AC line's limited bandwidth. I'd be interested to hear what you come up with. - CAL