+ Post New Thread
Results 1 to 5 of 5
  1. #1
    Full Member level 5
    Points: 3,340, Level: 13

    Join Date
    Oct 2006
    Posts
    310
    Helped
    2 / 2
    Points
    3,340
    Level
    13

    Leaky Coaxial Cable radiation

    hi,

    I want to discus the leaky coaxial cable intruder detection system presented in the attach file. I am confused bout the detection method described in this document. At page 14 it says

    " It is necessary to address the issue of sampling rate. The sampling rate used to
    capture the waveforms is 3 KHz. According to (10) this is way below the required
    sampling rate in order to monitor the 150 MHz signal. While this is true, our detection
    method does not need accurate monitoring and reconstruction of the signal, and, instead,
    designed so that it relies on aliasing to detect the change in amplitude. We do not need to
    sample at 300 MHz (10) in order to detect the change in magnitude. Our signal of
    interests is the modulated carrier frequency created by the movement of the
    intruder/extruder and therefore 3 KHz is enough to catch the set of samples at which the
    amplitude has changed. The use of 150 MHz was simply because the tLCX leaked
    signals of the frequency the most."

    How FM modulation is occurred there?

    •   Alt14th September 2017, 11:05

      advertising

        
       

  2. #2
    Super Moderator
    Points: 233,774, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    40,390
    Helped
    12338 / 12338
    Points
    233,774
    Level
    100

    Re: Leaky Coaxial Cable radiation

    Where do you see FM involved? It's not mentioned in the report at all.


    1 members found this post helpful.

    •   Alt14th September 2017, 11:30

      advertising

        
       

  3. #3
    Full Member level 5
    Points: 3,340, Level: 13

    Join Date
    Oct 2006
    Posts
    310
    Helped
    2 / 2
    Points
    3,340
    Level
    13

    Re: Leaky Coaxial Cable radiation

    Sorry i miss-typed . it "modulated carrier frequency"

    "modulated carrier frequency created by the movement of the intruder" , what does it mean?



    •   Alt14th September 2017, 11:36

      advertising

        
       

  4. #4
    Super Moderator
    Points: 233,774, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    40,390
    Helped
    12338 / 12338
    Points
    233,774
    Level
    100

    Re: Leaky Coaxial Cable radiation

    It essentially means AM by variation of the reflected 150 MHz signal.


    1 members found this post helpful.

  5. #5
    Full Member level 5
    Points: 3,340, Level: 13

    Join Date
    Oct 2006
    Posts
    310
    Helped
    2 / 2
    Points
    3,340
    Level
    13

    Re: Leaky Coaxial Cable radiation

    Thanks for reply.

    The receiving cable is directly connected to the ADC module. Can i place a super-hetrodyne or direct conversion receiver at the receiver side?



--[[ ]]--