Sending a PWM signal over the power line.

Hello there!

I am currentlydesigning a project that uses an electrical bus system. and in that bus system i want to be able to send a data signal through the power line.

In theory it should work as following. Via an application on my mobile phone i want to send "Living room light on" for example. Then the application sends a signal to the arduino card. The arduino card should then send a signal out on the power line to a microprocessor, which is attached to the lamp in the living room, then decodes the signal and notice that the code is destined for that processor and turn the light on via a relay.

I've worked out the first step with the application to the arduino signal.

Heres the question, since it's possible to give the PWM port a frequency of 31,5kHz I would like to send out a PWM signal on the power line, then via a high pass filter(filtering out the 50Hz AC on the power line) send the signal to the microprocessor. Do i need to make the signal AC, because with PWM its 0-5Volts im sending out which will make the Power line signal different. And say i want to send a certain string with 0 and 1 to the microprocessor, how would that be possible with a PWM signal.

Hi,

I am not sure what you are doing is allowed by the power company's rules for using their grid. You might want to check up on that. Imagine all the noise that would be sent out if more people start to send signals via mains.

Buy a Belkin.

This is a student project so im not using the real power line, I am going to use a 12 V AC to symbolize the real net. So i want to try and make it on my own without buying already finished products

You might study how the commercial X-10 system sends data signals through the household power wiring. Briefly, short bursts of high frequency audio signals encoding digital data are sent at the 50/60Hz AC zero crossing intervals.

You can already buy home automation solutions that do this.

You could also use an off-the-shelf Ethernet over mains transceiver to enable an Arduino or other device with an Ethernet interface to communicate. You could use similar products supporting phone or serial data connections over mains if that is closer to what you want.

If you want to make your own mains transceiver, that's difficult and potentially dangerous.

If you want to make your own pretend version of a mains transceiver that sends over a low voltage circuit, you need to explain how this is going to be any different to using a plain bit old of wire. It's possible, if you know enough electronics to apply a carrier to an existing AC circuit, but why you would want to and whether you know enough to do it isn't clear.

It’s Ultrasonic not audio

this is actually feasible, what ever the noise will be created, it will be cancelled anyway by our home appliances rectifiers, transpormers or for AC motors this is negligible anyway, static electrical noises are everywhere thus this are normal in our electrical systems.