Power Line Communication, Coupling, Isolation , Help !!!!

Hi everybody

I wonder if any body can help me in the idea of coupling and isolation in the power line communication concept.

I have built the modulator, i still have to inject the communication signal into the power line, while blocking the power signal toward my circuit.

Any body can help ?

This is not new. There are many papers on how X-10 works. There is also a format for sending serial data over power lines using 200khz carrier. National has a very old application on sending audio over power line. (using a modulator)

Thnaks for the reply, but as i meantioned earlier, the problem is not with the data to be sent or the format how to send it, in fact the problem is in electronic design and concepts that i lack which is how to block the power signal from my circuit, while allowing the communication signal toward the power line.

I've read about this and this requires a transformer (for isolation) and capacitors for coupling. I dont know how to design the transformer and what parameters required for the design procedure. a ready project has beeen read and found that the transofrmer used was simply a coil and a hand wound wire above it, but not mentioning the procedure. I appreciate any help in this domain

Thanks in advance

Years ago, when I was toying with power line comms, I would use a
6-12v to 120v transformer with a 0.1 uf in series with the high side.
Quick and dirty, but it worked. Commercial products usually use a
specialty coupling transformer, or none at all - just a cap for isolation.
A lot depends on whether the device is bi-directional.
<als>

Thanks for your information fsmyth, must the voltage at the low side be a specific one? means does it need to be 6 or 12? another question, supposing that i want to implement a transformer for a transmitter and another one for a reciever can you please provide me with information as much as you can please ?

I was trying to send you to this application note.
https://www.electro-tech-online.com/custompdfs/2009/03/AN-146.pdf

I used a 'pulse' transformer with 1000 volts of isolation. You can use a IF transformer but the isolation is not good. In the application note thay connect the transformer across the power line with a 0.1uf 200 volt capacitor. If you use 2 capacitors, one on each leg of the transformer then I think you can use a low voltage transformer.

SparkFun Electronics - Powerline Communication Modem PLC-UART XBee

Some more helpful info

Dear ronsimpson
Thanks for the helpful document u provided, but i still have a problem, the components RAN-10A6729EK and RAN-10A6845EK used in this article are not found ! do u know other alternative, if not please provide me with a clear idea about the transformer have you wound it your self or just used a ready one ? I'm too much confused about this subject

At digikey.com I typed in 10A6729EK and found the data sheet from Toko. Digikey did not have any parts but now you know the inductance and turn ratio. You are looking for a IF transformer that will resonate at you frequency.

Dear ronsimpson,
The project you posted is too much important, I dont not if I'm asking too much, but plz i need help!
Did you meant in your last reply that I can do a similar coil to those I requested? please provide me with clear response ! too urgent