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Systems and methods for monitoring speed

  • US 7,426,450 B2
  • Filed: 01/09/2004
  • Issued: 09/16/2008
  • Est. Priority Date: 01/10/2003
  • Status: Expired due to Term
First Claim
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1. A method for measuring a speed of a vehicle approaching an intersection as the vehicle passes through a field of view of a dual transducer sensor configuration, the method comprising:

  • receiving one or more signals at a first transducer of the dual sensor configuration, the one or more signals received at the first transducer being reflected off of or emanating from a vehicle as the vehicle passes through a first field of view of the first transducer;

    receiving one or more signals at a second transducer of the dual transducer sensor configuration, each of the one or more signals received at the second transducer having a time delay relative to a corresponding signal received at the first transducer resulting in a series of time delays between signals received at the first transducer and signals received at the second transducer, the one or more signals received at the second transducer being reflected off of or emanating from the vehicle as the vehicle passes through a second field of view of the second transducer, wherein the second field of view at least partially overlaps with the first field of view;

    performing a plurality of correlations between the one or more signals received at the first transducer and the one or more signals received at the second transducer, wherein the result is a correlation function indicating the correlation between signals received at the first transducer and signals received at the second transducer for the series of time delays;

    identifying a time delay, from among the series of time delays, corresponding to a peak correlation in the correlation function;

    determining the speed of the vehicle using the identified time delay and a distance between the first transducer and the second transducer;

    using the determined speed to monitor the safety of the intersection;

    the first transducer transmitting one or more transmitted signals into the field of view of the first transducer; and

    the second transducer transmitting one or more transmitted signals into the field of view of the second transducer such that the one or more transmitted signals transmitted into the field of view of the second transducer at least partially overlap with the one or more transmitted signals transmitted into the field of view of the first transducer.

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