Ground-speed Doppler radar for vehicles
First Claim
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1. In a Doppler radar system wherein the speed of an object is detected from a frequency shift of microwaves emitted from an antenna carried by the object and reflected from a stationary surface;
- the improvement comprising a detecting circuit which detects a differential factor of the frequency shift, a threshold circuit which discriminates whether or not the output of said detecting circuit lies within a certain range of values, and a control circuit which varies the frequency of the microwaves emitted from the antenna on the basis of an output of said threshold circuit indicating that the output of said detecting circuit lies within said certain range of values.
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Abstract
A Doppler radar wherein, in order to measure the ground speed of an automobile, microwaves are radiated to the ground and the Doppler shift of reflected waves from the ground is detected, characterized in that to the end of avoiding a malfunction ascribable to an external microwave interference, when the differentiated output of the Doppler radar is greater than a threshold value, the frequency of the microwaves of the Doppler radar is controlled so as to prevent the microwave interference from taking place.
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Citations
12 Claims
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1. In a Doppler radar system wherein the speed of an object is detected from a frequency shift of microwaves emitted from an antenna carried by the object and reflected from a stationary surface;
- the improvement comprising a detecting circuit which detects a differential factor of the frequency shift, a threshold circuit which discriminates whether or not the output of said detecting circuit lies within a certain range of values, and a control circuit which varies the frequency of the microwaves emitted from the antenna on the basis of an output of said threshold circuit indicating that the output of said detecting circuit lies within said certain range of values.
- View Dependent Claims (2, 3, 4, 5)
- 6. In a Doppler radar system for detecting the speed of an object from a detected Doppler signal, the improvement comprising a differential circuit connected to receive said Doppler signal for producing an output representative of the rate of change of said Doppler signal, a threshold circuit connected to receive the output of said differential circuit for producing a control signal when the rate of change of said Doppler signal exceeds a predetermined value, and control means responsive to said control signal for adjusting an operating characteristic of said Doppler radar system.
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8. A Doppler radar system for detecting the speed of an object comprising microwave transmission means for transmitting a microwave signal at a selected frequency;
- signal reception means for receiving a reflected microwave signal and for producing a Doppler signal representing the speed of the object by comparing said transmitted microwave signal and said received reflected microwave signal;
differentiating means for detecting the rate of change of said Doppler signal indicating the acceleration of the object and for producing an output representative thereof;
threshold means for producing a control signal when the output of said differentiating means indicates a value of acceleration which the object is incapable of achieving, and control means responsive to said control signal produced by said threshold means for changing the frequency of the microwave signal transmitted by said microwave transmission means. - View Dependent Claims (9, 10, 11, 12)
- signal reception means for receiving a reflected microwave signal and for producing a Doppler signal representing the speed of the object by comparing said transmitted microwave signal and said received reflected microwave signal;
Specification