need help in working with RF module interfacing

Discussion in 'Embedded Systems and Microcontrollers' started by bobparihar, Sep 18, 2014.

  1. bobparihar

    Thread Starter Member

    Jul 31, 2014
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    I am using a circuitry to send data through wireless.. using RF of frequency 433Mhz
    my circuit is as follows
    the problem here is that this works only when i connect both transmitting and receiving circuit to a common ground.
    but in wireless communication i cant use a common ground to both transmitter and receiver as they are apart from each other.
    could someone tell me a better solution

    basically i am using a single wire instead of RF transmitter and receiver just to check that my encoding and decoding circuit working properly or not
     
  2. sirch2

    Well-Known Member

    Jan 21, 2013
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    But when you actually use RF, rather than wires, the planet earth acts as a common ground. If it works over a wire with a common ground, try it with the RF modules.
     
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  3. Arm_n_Legs

    Active Member

    Mar 7, 2007
    183
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    If you are using the same Vcc, then of course they need the same ground.
     
  4. ligo.george

    New Member

    Feb 2, 2013
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  5. bobparihar

    Thread Starter Member

    Jul 31, 2014
    93
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    Iam using seprate vcc for both ends
     
  6. bobparihar

    Thread Starter Member

    Jul 31, 2014
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    I did use rf module and it works.. but here a new problem..
    Basicly i am using 433Mhz rf module.. so the range should be about 80-100m
    But in my case i acheive only less then 2m range.. beyond it..its not working..
    Dont knw where is the prblm.. plz help sm1
     
    Last edited: Sep 25, 2014
  7. sirch2

    Well-Known Member

    Jan 21, 2013
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    Please provide details of the RF modules. Have you connected antennas to both of them? Are they in boxes or enclosures?
     
  8. bobparihar

    Thread Starter Member

    Jul 31, 2014
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    yes i have connected a wire antenna of about 5cm
     
  9. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    I think that the antenna is to short.
    Wave lenght for 433 MHz is about 300/433 = 0.693 meter.
    A quarter wave will be 0.693 / 4 = 0.173 meter => ca. 17 centimeter.

    Bertus
     
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  10. bobparihar

    Thread Starter Member

    Jul 31, 2014
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    iam somewhat confused here.. here in my circuit diagram it uses 750k ohm between the pin n0. 3 and 4 of encoder for oscillator and 27 k ohm at the decoder end..
    but in some tutorials i have seen 1M ohm at the encoder and 33K ohm at the decoder..
    well i have seen what iam doing in many tutorial too..
    can some one explain this? does iam doing somthing wrong?
     
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