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Re: Kinect tear down

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  • dan michaels
    ... I m a little remiss to post this link, as last time I did so to one of my pages, I got a lot of criticism that everything on the page was wrong [LOL].
    Message 1 of 126 , Dec 1, 2010
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      --- In SeattleRobotics@yahoogroups.com, "Peter Balch" <peterbalch@...> wrote:
      >
      > Dan
      >
      > > > they're using a PIC16F690 to subsample the camera's
      > > > 260line composite video to give an 18×16 image at 4 grey levels
      > > >
      > > However, undersampling works fine with a PIC as long as you have
      > > a stable trigger, and they derive that from the analog video
      > > signal using an LM1881, which has been around for decades.
      >
      > Yes-ish. I designed a product last year that put a white square on the > top-left of a video signal - to synchronise the recorded video with another > signal. The question was analogue or digital? An analogue circuit of > monostables has many more components but the timing is "clean".
      >



      I'm a little remiss to post this link, as last time I did so to one
      of my pages, I got a lot of criticism that everything on the page
      was wrong [LOL]. However, this does show that 100-Khz waveform
      sampling is possible on a PIC, using equivalent-time sampling
      techniques. The trigger ckt was just an LM393 fed by an opAmp
      amplifier. I won't say how I did it, as a lot of the current
      interest involves commercialization, so you can figure it out for
      yourself. :) Circa 2001 ...

      http://www.oricomtech.com/projects/ets.htm

      The 50- and 100-Khz signals have pretty good fidelity. My guess
      is, it still wouldn't be near fast enough for video, except for
      lower-resolutions, up to maybe 32x32 or 64x64 with the faster
      PICs. That still might not be too bad, for a simple electronics
      ckt.


      >
      > The client eventually asked for a simpler digital circuit: LM1881, an 8-pin > PIC and a couple of resistors. The problem is that the PIC can only > start/stop the white signal on its internal (1Mips) clock edge and the > internal clock isn't related to the video timing. So there's 1uS jitter on > the horizontal edges on the square - they're really ragged. It looks horrid > but is prefectly functional.
      >
      > So for a sub-sampled camera, I'd want to sample the video at a more
      > precisely controlled "correct" time. Either have fixed sample windows > controlled by analogue monostables or maybe the PIC clocked by a PLL locked > to the video syncs.
      >
      > Peter
      >
    • David Buckley
      You mean the SPO256 by GI, 28pin DIL ? They also had a 40 pin DIL CTS256A-AL2 text to speech for spo256 I have use the SPO256 back in the 80s and also last
      Message 126 of 126 , Dec 12, 2010
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        You mean the SPO256 by GI, 28pin DIL ?
        They also had a 40 pin DIL CTS256A-AL2 text to speech for spo256
         
        I have use the SPO256 back in the 80s and also last month but never got around to using the latter, I do have the Tandy data that came with them (somewhere I hope).
         
        David - robots42
         
         
        ----- Original Message -----
        Sent: Sunday, December 12, 2010 11:26 PM
        Subject: Re: [SeattleRobotics] Re: Speech and frequency vs time

         

        A long time ago, when Radio Shack still sold IC's, I got a speech
        synthesizer set, but I never did anything with it. Has anyone used them?

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