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MEASUREMENT OF THE VELOCITY OF A BODY

  • US 3,804,518 A
  • Filed: 05/01/1972
  • Issued: 04/16/1974
  • Est. Priority Date: 05/05/1971
  • Status: Expired due to Term
First Claim
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1. A device for the measurement of the speed of a body which is moved parallel to a surface, which has a local irregular feature, comprising one leading and one trailing converter means spaced above the surface to produce two sequences of electrical signals which correspond with the feature of the surface at two points running together with the body, said leading and trailing converter means being spaced one from the other in the direction of movement, a delay unit with an adjustable delay for the signals emanating from the leading converter means, a multiplier circuit for the multiplication of the delayed signals of the leading converter means by the undelayed signals of the trailing converter means, a low pass filter connected to the output of the multiplier circuit, a control circuit connected to said low pass filter for the adjustment of the delay of said delay unit in dependence of the output of said multiplier circuit to a value which corresponds to a timely coincidence of the delayed and undelayed signals, and at least one indicating device, which on the adjusted basis of the delay of the delay circuit and the spacing of the points indicates the relative velocity and/or the path travelled onward from a given point, two filters, each interposed in the connection between one of said converter means and the multiplier circuit, and the said filters having different frequency characteristics which are so chosen that the value obtained at the output of the low pass filter is zero, when the delayed signal and the undelayed signal timely coincide, said control circuit adjusting the delay of the delay unit so that the output of said multiplier circuit is zero.

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