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Digital transceiver chips

  1. Jun 10, 2008 #1
    is there electronic transceiver chips that can transmit very low frequencies (1Hz-90KHz) for digital signals of low power, and small antenna chips for that frequency. from what I was reseaching I could find anything under a couple of MHz. But does using a digital encoder make a difference.
     
  2. jcsd
  3. Jun 10, 2008 #2

    mgb_phys

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    Very Low frequency VLF is used to transmitto submarinesand underground in eg. mines.
    The problem is that you need very large antenaes - since the wavelength is so long.
    You also need a lot of power to penetrate a large amount of rock or water in practical systems and the data rate is very low.
    Onthe plus side, the frequency is low enough that you detect the waves directly and can do the mixing in software.

    Generally you do use a lot of signal processing because there is a lot of background noise and thesesignals generally have important messages you don't want to get wrong!
     
  4. Jun 10, 2008 #3

    berkeman

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    As mgb says, if you are asking about using VLF carriers, then no, everything has to be physically large. Antennas are typically on the order of a quarter to a half wavelength of the EM radiation carrier in the air.

    But if you are asking about transmitting low data rate information, you can do that with an RF carrier (as long as you meet the FCC regulations about RF transmissions in various bands, etc.).

    Are you asking about VLF carrier transmissions, or low datarate RF transmission? BTW, the government would likely get very, very unhappy if you started stepping on submarine communications....
     
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