Ultrasonic ground speedometer utilizing doppler effect
First Claim
1. An ultrasonic ground speedometer utilizing Doppler effect comprising:
- ultrasonic transmitting means for outputting an ultrasonic wave at a predetermined angle against a road surface;
ultrasonic receiving means for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from the road surface;
arithmetic means for deriving ground speed from Doppler shift between the frequencies of the output ultrasonic wave from said ultrasonic transmitting means and the reflected ultrasonic wave received by said ultrasonic receiving means;
means for controlling the output ultrasonic wave frequency in such a manner as to keep the reflected ultrasonic wave frequency represented by the sum of the output ultrasonic wave frequency and the Doppler shift to a constant value in response to change in the ground speed derived by said arithmetic means; and
means for controlling the amplitude of the output ultrasonic wave to keep a substantially constant intensity of the output ultrasonic wave over the output ultrasonic wave frequency range controlled by said output frequency controlling means.
1 Assignment
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Accused Products
Abstract
An ultrasonic ground speedometer utilizing Doppler effect comprises an ultrasonic transmitter for outputting an ultrasonic wave at a predetermined angle against a road surface, an ultrasonic receiver for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from a road surface, an arithmetic circuit for deriving ground speed from Doppler shift between the output ultrasonic wave and the reflected ultrasonic wave. The ultrasonic ground speedometer also includes an output frequency control circuit for controlling the output ultrasonic wave frequency in such a manner as to keep the reflected ultrasonic wave frequency to a constant value in response to changes in ground speed. An amplification degree control circuit is also included for controlling the amplitude of the output ultrasonic wave to keep a substantially constant output intensity of the output ultrasonic wave over an output ultrasonic wave frequency range controlled by the output frequency control circuit.
10 Citations
7 Claims
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1. An ultrasonic ground speedometer utilizing Doppler effect comprising:
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ultrasonic transmitting means for outputting an ultrasonic wave at a predetermined angle against a road surface; ultrasonic receiving means for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from the road surface; arithmetic means for deriving ground speed from Doppler shift between the frequencies of the output ultrasonic wave from said ultrasonic transmitting means and the reflected ultrasonic wave received by said ultrasonic receiving means; means for controlling the output ultrasonic wave frequency in such a manner as to keep the reflected ultrasonic wave frequency represented by the sum of the output ultrasonic wave frequency and the Doppler shift to a constant value in response to change in the ground speed derived by said arithmetic means; and means for controlling the amplitude of the output ultrasonic wave to keep a substantially constant intensity of the output ultrasonic wave over the output ultrasonic wave frequency range controlled by said output frequency controlling means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification