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Ultrasonic depth measurement apparatus and methods

  • US 4,679,160 A
  • Filed: 12/13/1984
  • Issued: 07/07/1987
  • Est. Priority Date: 12/13/1984
  • Status: Expired due to Term
First Claim
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1. Apparatus for determining the depth of precipitation accumulating on the surface of a pathyway, comprising:

  • a sensor having an electrical transducer for emitting and sensing ultrasonic energy and having a body of material for propagating the ultrasonic energy therethrough, which body is to be embedded in the pathway with the top surface of the body being substantially flush therewith and exposed to the precipitation, said transducer being physically coupled to the body;

    means for supplying electrical pulses to said transducer to cause it to emit pulses of ultrasonic energy, which are reflected as first and second reflections from the top surface of the body and from the upper surface of an accumulation of precipitation on the top surface of the body and are respectively returned to said transducer which in response to the reflected pulses produces corresponding first and second electrical signals;

    means connected to said transducer for amplifying the first and second electrical signals corresponding to the first and second reflections, thereby to produce an amplifier output;

    means connected to said amplifying means for initiating a first timing signal upon the occurrence of the first electrical signal;

    means for comparing the amplifier output with a threshold level which has a magnitude that decreases with time, the operation of said comparing means being started upon an occurrence of the first timing signal, the comparing means initiating a second timing signal when the amplifier output reaches the threshold level; and

    means for generating a third electical signal representing the depth of the precipitation as a function of the time interval between occurrences of the first and second timing signals.

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