Radar detector
First Claim
1. A radar detector comprising:
- a mixer for performing frequency-conversion of an incoming electromagnetic wave radar signal to a corresponding input frequency signal;
a local-frequency sweeping circuit for providing to said mixer a local signal whose frequency varies with time in a fixed frequency range;
an FM detector circuit for performing FM-detection on said input frequency signal, thereby providing a detection signal having higher-frequency or noise components therein, these components being suppressed when said input frequency signal matches said local signal in frequency;
a frequency-sweep controlling circuit responsive to disappearance of said noise components in said detection signal for preventing said local-frequency sweeping circuit from continuing the frequency sweep for a fixed length of time; and
means for distinguishing said incoming electromagnetic wave radar signal from interference signals on the basis of the lengths of time for which said noise components are suppressed in said detection signal during the temporary discontinuation of the frequency sweep in said local-frequency sweeping circuit.
1 Assignment
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Accused Products
Abstract
A radar detector capable of discriminating a prescribed radar signal from other undesired radar or interference signals by mixing an incoming electromagnetic wave radar signal with a local signal whose frequency varies with time within a fixed range of frequency repeatedly at regular periods, thus providing a beat signal; temporarily stopping the frequency sweep in response to appearance of dc components alone in the beat signal when the incoming radar signal matches the local signal in frequency; and watching the length of time for which the incoming radar signal matches the local signal in frequency. The reception of the prescribed radar signal is indicated using a sound-generating unit such as a speaker or a light-emitting unit.
30 Citations
8 Claims
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1. A radar detector comprising:
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a mixer for performing frequency-conversion of an incoming electromagnetic wave radar signal to a corresponding input frequency signal; a local-frequency sweeping circuit for providing to said mixer a local signal whose frequency varies with time in a fixed frequency range; an FM detector circuit for performing FM-detection on said input frequency signal, thereby providing a detection signal having higher-frequency or noise components therein, these components being suppressed when said input frequency signal matches said local signal in frequency; a frequency-sweep controlling circuit responsive to disappearance of said noise components in said detection signal for preventing said local-frequency sweeping circuit from continuing the frequency sweep for a fixed length of time; and means for distinguishing said incoming electromagnetic wave radar signal from interference signals on the basis of the lengths of time for which said noise components are suppressed in said detection signal during the temporary discontinuation of the frequency sweep in said local-frequency sweeping circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification