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Pulse Amplitude Modulation

Discussion in 'General Electronics Discussion' started by TheWookie, Mar 13, 2013.

  1. TheWookie

    TheWookie

    2
    0
    Mar 13, 2013
    Hi,

    I'm working on a project to get some old Cold War equipment up and running (WB1400 HANDEL National Attack Warning system if anybody is familiar)

    I need to build something to replicate the signals it would expect to recieve from the Carrier Control Point. It appears to be using Pulse Amplitude Modulation in order to send digital data over an analogue network.

    For starters here's the signal required to "wake up" the Signalling Reciever box. It's normally asleep and ignores everything except:

    Six 800ms bursts of 1.5khz modulated on a 72khz AM carrier, sent down a wire.

    Modulating something onto a carrier is straightforward enough, as is sending it down a wire rather than radio transmission... but how do you control the number and duration of the bursts ?

    I'm guessing some sort of programmable logic control? would a PIC do that sort of thing?
     
  2. BobK

    BobK

    7,645
    1,662
    Jan 5, 2010
    Yes, you can do this with a PIC. Just for kicks once, I put out a modulated 1MHz signal from a PIC using the PWM module and verified I could pick it up on an AM radio. 72KHz should be no sweat.

    Bob
     
  3. TheWookie

    TheWookie

    2
    0
    Mar 13, 2013
    Thanks Bob, I'll look into going down that route then. Need to dig out some of my old College notes.

    Bit of reverse engineering going on here starting at the receiver end and working back, although I do have the advantage of modern technology
     
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