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I'm now considering TDA5051A to transmit information over the 230VAC power network. To avaid any interference between neightbours I will need to stop transmision beyond the appartment electrical network.

As I understand from its datasheet the transmission will be at the frequency about 132 kHz. From my point of view it will be enough to place some filter (i.e. place a ferrite bead at the apartment main inlet). But I'm afraid that this can suppress the signal in the areas where I don't need any suppression.

Graphics:

enter image description here

T/Rn - Digital transmitter and receiver.

Ground and neutral wires are not shown here for simplicity reasons.

In real world there is a transformer between HV power line and an apartment, please consider the line on the transmission towers as a 230VAC line.

So the question is: if the conception is correct - what kind of filter I should use if the signal is 132 kHz and main AC frequency is 50/60 Hz?

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  • \$\begingroup\$ Did your previous question get a satisfactory answer: electronics.stackexchange.com/questions/161560/… ? If not you should consider how to add more detail to it to help you. \$\endgroup\$ – Andy aka Apr 13 '15 at 11:57
  • \$\begingroup\$ @Andyaka, this Q was mainly about how to skip TDA5051A. After I read about this chip I decided not to skip it as it has very reasonable solution for signal modulation - I will not be able to do anything similar within a (size, price and time) budget. One particular subquestion (4) was about the filter, but there was no answer on it at all. \$\endgroup\$ – Roman Matveev Apr 13 '15 at 12:03
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    \$\begingroup\$ Q4 wasn't answered because connecting an unspecified RF signal to a cable can make it an antenna irrespective of whether a blocking filter is used or not. \$\endgroup\$ – Andy aka Apr 13 '15 at 12:11
  • \$\begingroup\$ Agree, @Andyaka! Hope that I will have an answer in this question :) \$\endgroup\$ – Roman Matveev Apr 13 '15 at 12:20
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    \$\begingroup\$ No I don't think it will. The powerline comms is about 130kHz and most ferrite beads don't start attenuating until well above 1MHz plus you have to consider the regular AC current flowing thru the ferrite bead might saturate it. It's got to be a "sizable" power inductor and it will probably also need a capacitor to act as an additional low pass filter on the incoming live and neatral to the house. As I said in my previous answer, your best bet is to design a comms protocol that allows for data collisions between two houses. \$\endgroup\$ – Andy aka Apr 13 '15 at 14:06
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Just about any EMC filter will work for that frequency, check their charts. They generally have an effect from 100 kHz and up, and you'll need at least 30-40 dB attenuation. Remember that the filter must handle the amps for the main, and that can be quite costly.

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