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Radar ground speed sensing system

  • US 4,489,321 A
  • Filed: 05/05/1983
  • Issued: 12/18/1984
  • Est. Priority Date: 05/05/1983
  • Status: Expired due to Term
First Claim
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1. A radar speed sensing system for a vehicle moving over terrain, comprising:

  • means for generating high frequency electromagnetic energy and for providing a Doppler signal representative of a frequency difference between a return part of said high frequency energy and the generated energy;

    directing and receiving means directing at least a portion of said generated energy along an axis intersecting with said terrain and receiving along said axis a returned part of said generated energy directed along said axis;

    means for converting the Doppler signal to an input pulse train having input pulses with pulsewidths and frequency related to a ground speed of the vehicle; and

    signal processing means for receiving said input pulse train and for converting said input pulse train to an output pulse train having output pulses with pulsewidths and frequency related to vehicle ground speed, the signal processing means comprising;

    (a) means for ignoring input pulses having a pulsewidth greater than a predetermined threshold pulsewidth;

    (b) means responsive to a predetermined consecutive number of a first kind of said input pulses, all having a pulsewidth deviating by more than a predetermined amount from a predetermined output signal pulsewidth, for generating an average input value representing an average of the pulsewidths of said predetermined number of the first kind of said input pulses;

    (c) means for deriving a first output value from the average input value and a stored output signal pulsewidth value;

    (d) means responsive to a second kind of said input pulses, having a pulsewidth deviating by not more than said predetermined amount from said predetermined output signal pulsewidth, for deriving a second output value from a pulsewidth value of said second kind of said input pulses and from a stored output signal pulsewidth value; and

    (e) means for generating the output signal pulse train as a function of the first and second output values, the output pulse train having output pulses with pulsewidths and frequency related to the first and second output values and to the vehicle ground speed.

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