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Initially I need to communicate between several devices placed within one appartment (or a building). All those devices will be connected to 230 VAC power line.

I'd like to skip any wireless communication as it will not guarantiee that neighbours will not interfere with each other.

And I'd like to have a cheap and small solution.

Initially I stuck with TDA5051A which is created directly for what I need. In addition its datasheet including detailed application schemes:

enter image description here

However the chip is moderately big (10mm long SO16 package) and a bit pricie (about $3/piece not including price of additional needed components).

So this is why I turned to figure out how to do this with in the same way as RF-wireless communication does. But instead of the air I will use 230VAC power line as the medium:

enter image description here

So my questions are:

  1. Is it enough to use a capacitor between the powerline and the transceiver?

  2. Which wire is better to use for communication: line of neutral?

  3. How can I be sure that the signal will reliably transmitted within one single powerline wire AND will not be transmitted wirelessly with any significant power to the neighbours electrically isolated powerline wires?

  4. Is it possible to place any filter at the apartment (or building) inlet to restrict data transmission to/from neighbours?

  5. I will be very appreciated if anyone will share ready-to-use schematic

  6. Is there anything else I should think about or take into account?

Thank you in advance!

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  • \$\begingroup\$ What makes you think that the neighbor's power is electrically isolated from yours? You're both probably connected to the same low-voltage distribution transformer. \$\endgroup\$ – brhans Mar 25 '15 at 12:45
  • \$\begingroup\$ @brhans I can not be sure. And it will take place most of the times! This is why I asked 4'th question. \$\endgroup\$ – Roman Matveev Mar 25 '15 at 12:53
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This question assumes that connecting an RF signal to a power line does not convert the power line into an antenna. The power line will become an antenna and you will find that neighbors will in fact interfere with each other.

It's also quite probable (in some cases) that powerline comms will extend their range to neighbouring houses.

So, what you need to do is think about using some kind of protocol that can allow neighbours to interfere with each other without this necessarily causing an operational problem.

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  • \$\begingroup\$ You're right! Power line will be an antenna. However I expect that signal induced on the neightbour wire will be much weaker than the one within one wire. So I could cut any signals weaker that something and let it go. \$\endgroup\$ – Roman Matveev Mar 25 '15 at 11:47
  • \$\begingroup\$ Some powerline nodes may receive a bigger signal from next doors powerline comms via direct EM transmission. You can't rule this out so, develop a protocol that allows several disparate systems to co-exist. \$\endgroup\$ – Andy aka Mar 25 '15 at 11:53
  • \$\begingroup\$ Saying direct EM you mean conductive EM? \$\endgroup\$ – Roman Matveev Mar 25 '15 at 11:54
  • \$\begingroup\$ I mean an EM transmission via air. Many factors will cause a node to receive a poor wanted signal via the powerline whilst a neighbor's powerline may cross contaminate (via air waves) that node causing the received signal to be dominated by the interferer. \$\endgroup\$ – Andy aka Mar 25 '15 at 12:02
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    \$\begingroup\$ Of course it can - these are transmission systems and are subject to total signal cancellation sometimes from within their own system. Look up transmission line theory (a very big subject that does take years to grasp). An interfering signal is likely to be much larger than the supposed "direct connection" signal due to cancellation on the power lines typically because of ring mains for example. \$\endgroup\$ – Andy aka Mar 25 '15 at 12:27

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