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Power Line Communication

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by embedded_sys, Feb 26, 2018.

  1. embedded_sys

    embedded_sys Member

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    I need to communicate about 1500 feet between two devices, and I would like to do it with power line communication. I found two chips, TDA5051 and CY8CPLC20. I don't need a lot of bandwidth. What is the standard or one of the standard chips used for power line communication?
     
  2. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Power line communications I have used will not pass though a transformer. (not well) So I hope both locations are on the same transformer. I don't know you location! In the use most houses have two phases of power. So here it really helps to have the transmitter and receiver on the same phase.

    Years ago I use a TDAxxxx power line modem that worked well. 120 or 130khz

    I do WiFi more than 1500 feet with a directional antenna.
    Xbee pro 900 will do 1500 (line if sight)
     
  3. embedded_sys

    embedded_sys Member

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    I am on the same transformer, and I can't use WiFi or another radio unfortunately. The application example looks pretty complex. Connection to the MCU and the clock input look pretty straight forward. Is there a simplified way or is this the best way? There are also several application examples. Which should I choose?

    Screen Shot 2018-02-26 at 4.58.33 PM.png
     
  4. dave miyares

    Dave New Member

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  5. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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  6. dr pepper

    dr pepper Well-Known Member Most Helpful Member

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    I prototyped something like this but never used it, the system was for security lighting, initially I had complicated lash up but eventually realised it was well Ott and just ended up using the arduino tone library and a Ne567 tone decoder, audio freq's pass through a small mains transformer Ok (but not a substation transformer).
    Datarate is obviously slow a few tens of bits per S, depends what you need.
     
  7. embedded_sys

    embedded_sys Member

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    What kind of range could I expect with a TDA5051AT chip?
     
  8. dave miyares

    Dave New Member

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  9. AnalogKid

    AnalogKid Well-Known Member

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  10. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    I don't know. There are so many factors. I found that a "PC" power supply is hard on power line communications.
    The "X" and "Y" capacitors in switches short out the signal. These caps are form line-line and line-ground.
    And if the switcher is running at 120khz it is not good.

    I made some power strips with inductors added to the line and neutral. This way PC + monitor sit on a isolated part of the power line.

    I have some experiance with X-10. It talks 120khz and I can talk from house to house and to the barns. I have not tried 1500 feet.

    I have some "power line phone" things. Analog Kid in post #7. They are built for audio tones. They were really designed for one house distances. I think noise from (computers & band saws) is more of a problem then distances.
     
  11. embedded_sys

    embedded_sys Member

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    My line will not have any computers, but it will have a few relays. Will the inductance of the relay cause issues?
     
  12. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Inductance is fine. It is capacitors that short out high frequencies.

    I wish we had a way to test before you go to all the trouble to build something.
    Where I live there are "junk stores". It is common to find all kinds of used electronics. (working and not) I can often find "X-10" modules. They talk using the same method. If you had a transmitter and receiver we could do some testing. (a box of old unknown electronics is very low cost)

    Here is a picture of the remote modules. Most are just a relay on/off.
    upload_2018-2-27_16-33-35.jpeg
     
  13. embedded_sys

    embedded_sys Member

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    I wish I could test if before building too! I've got most things layed out now, and I'm trying to pick the right inductor. Spec sheet show an inductor of 47 μH low RS on the AC main line. What material and type of inductor should I be getting?

    Another inductor after the 78250 transformer is 22uH. Again, what material and type of inductor should I get?
     
  14. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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  15. embedded_sys

    embedded_sys Member

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    Great picture! I'm actually using that BOM, but it doesn't have specific part numbers. Should I get wirewound ferrite inductors?
     
  16. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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  17. canadaelk

    canadaelk Active Member

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    I have used the National LM1893 transceiver with great success. The datasheet is full of great info. I have also used DTMF (MK5807/5102). By using different X-tals to get non-overlapping frequencies it is easy to get 2x16 (or 256 with a 4TMF) outputs. E
     
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  18. embedded_sys

    embedded_sys Member

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    I've got everything coming to test out the TDA5051. I'm looking at the firmware side of things now. What kind of protocol do I need to use? I'm using an ESP32 as the MCU and level shifted DATA_IN, DATA_OUT, and CLK to work with the 3.3VDC tolerance.
     
  19. HarryC

    HarryC New Member

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    If you're only running one line 1500 feet with single-phase AC, then a variation of what X-10 did is about the best you can get with that chip (1ms pulse of signal is a ONE, lack of that pulse is a ZERO). I used the Philips NE5050 (similar tech) 15 years ago, and was underwhelmed with it's performance. Looks like they've corrected some of those old problems with the TDA5051, but it's still ASK at ~100KHz over a 1 to 5 ohm effective impedance (dirty) AC network. As long as you're able to deal with VERY low bit rate, you can get *maybe* a few bits out around the zero crossing each AC cycle. The AC lines are relatively quiet for about 2-3ms after the zero crossing, so ~240 to 360 bits per second. If the noise is too high (lots of triacs or other switching near the zero crossing), you might be limited to one bit per zero crossing / 120 bps raw, not counting overhead.

    If you have multiple 'thingies' talking on that 1500 foot line then you'll want some sort of CSMA/CD protocol, where you listen to your outgoing signal to see if it's being stomped on by another sender, at which point you back off and wait for 50 to 200 cycles of AC before trying again.

    You're probably locked into the TDA5051 due to time and money, but I think you'd probably have better luck over long-distance with the FSK chips. With X-10 there was a heck of a lot of redundancy to make sure that something happened at the far end... theirs was a 'dumb' network, where the slaves generally couldn't reply, only receive. That meant the error-proofing had to go in up front, as they couldn't ACK a good packet.

    And jeezus... if you're already using an ESP32 to drive this beast, why in the heck not WiFi?? You're inventing a horse and buggy all over again, when the rest of us are flying at 80MPH. For two nodes under $5 each, you can't beat the price. Add half-wavelength antennas and they'd do 1500 feet.
     

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