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Waveform peak capture circuit for digital engine analyzer

  • US 5,250,935 A
  • Filed: 09/24/1990
  • Issued: 10/05/1993
  • Est. Priority Date: 09/24/1990
  • Status: Expired due to Term
First Claim
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1. Apparatus for displaying on a screen of a digital oscilloscope a substantially accurate representation of an analog cylinder ignition waveform signal of a multiple cylinder internal combustion engine, said cylinder ignition waveform signal having a corresponding cylinder time period, said apparatus comprising:

  • analog-to-digital conversion means for receiving the analog waveform signal and digitizing it to produce a series of digital data samples at a first sampling rate, clock means for generating display sampling signals at a rate substantially less than said first sampling rate, peak capture means coupled to said conversion means for storing the maximum value of the digital data samples occurring between two consecutive display sampling signals, display drive means coupled to said clock means and to said peak capture means and to said conversion means and to the oscilloscope and responsive to each display sampling signal for selecting a digital data sample for display, said display drive means being operable in a first mode wherein it selects for display in response to each display sampling signal the value of the most recent sample from said conversion means and a second mode wherein it selects in response to each display sampling signal the sample value stored in said peak capture means, and control means for selectively operating said display drive means in either of said first and second modes, said control means including means automatically switching between said first and second modes within each cylinder time period on the basis of the nature of the analog waveform signal.

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