Power line modem BELL 202

Discussion in 'The Projects Forum' started by mmuj, Apr 12, 2016.

  1. mmuj

    Thread Starter Member

    Dec 15, 2009
    11
    0
    Hi

    I have just started working on a power line modem design using BELL 202 modulation (FSK 1200/2200 Hz marks space signal).

    There are quite a few design examples available from different chip manufacturers, e.g. TI, ON Semi etc. but all of these use CENELEC bands (starting from 9kHz, different modulation like OFDM, PSK variants etc.) but my project requirement is to use only BELL 202 standard signaling (it is imposed by the customer).

    There are few chips available for phone line and HART network BELL 202 modem but I can not find any for power line application. Using HART or phone line modem chip will have problem with power line noise and have no mechanism to deal with zero cross detection (used in power line modem to synchronize with 50/60Hz).

    If anyone know about off the shelf chip to handle modulation for power line application or any idea to deal with the project basic requirement of FSK BELL 202 modulation.


    Thanks in advance.

    mmuj
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,138
    1,789
    Power lines are pretty much guaranteed to make a really crappy transmission medium, and the way the power grid is constructed makes it really hard to transmit a signal over any appreciable distance. When BPL in the US fell apart for it's obvious disadvantages that pretty much ended the market for custom modem chips. I'm not saying they don't exist, but I've never seen one and can't imagine why anybody would want one, with ubiquitous broadband and wireless available over several different media types.
     
    Last edited: Apr 15, 2016
  3. mmuj

    Thread Starter Member

    Dec 15, 2009
    11
    0
    Thanks Papabravo

    I am thinking of modifying AFE031 reference design for 600V by changing coupling transformer and capacitors etc. I haven't found anything which suggest that low frequency transmission could be a problem using AFE031. All the graphs are showing 10kHz upward but frequency response is a straight line on 10kHz which indicates that there is no build in high pass filter. Although external band pass filter need to adjusted.

    I have been working on it and so far i can see that software modem (e.g. MSP430) + AFE031 + modified Mains coupling circuit will do it. Any suggestion?

    Regards,

    M Mujahid
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,138
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    Is this reference design you are referring to the same as Figure 49. in the datasheet?
    Which method of connecting the transmitter chain are you considering?
     
  5. mmuj

    Thread Starter Member

    Dec 15, 2009
    11
    0
    Yes, it is figure49.

    I will do some maths and use custom made transformer for my design.
     
  6. Papabravo

    Expert

    Feb 24, 2006
    10,138
    1,789
    You misunderstood my question. The datasheet shows different way of connecting the transmitter chain. One of the ways uses a Digital to Analog Converter(DAC). Is that the method you are using?
     
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