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US 4,538,249 AGranted
Ultrasonic doppler fish detector
OwnerJoseph D. Richardinventor
Life of this patent
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OwnerJoseph D. Richardinventor
Estimating the term…
A directional Doppler fish movement detector uses a relatively low ultrasonic frequency to minimize particulate scattering and absorption losses in turbid lakes and streams. The low ultrasonic frequency also minimizes Doppler noise caused by boat drift and wave action. To compensate for the relatively low frequency Doppler signals which result, including sub-sonic Doppler signals from slow moving fish, means are provided for doubling, or otherwise multiplying, the frequency of the Doppler signal to improve audibility. Means are also included which allow the relatively wide beam of the Doppler fish movement detector to be directed over a wide horizontal angle, and in one of the preferred configurations, the transducer assembly is attachable to the underwater portion of an electric propulsion motor so that the ultrasonic beam is directed along the line of thrust. Although useful for the detection of normally swimming fish, a preferred use is in cooperation with a fishing effort in which otherwise inactive fish are provoked into impulsive and detectable movements by bait casting into the area covered by the relatively wide ultrasonic beam.
An ultrasonic Doppler apparatus for detecting normal fish movements or reactive fish movements in response to a fish lure or other artificial stimulus comprising:
An ultrasonic Doppler apparatus for detecting actively swimming fish or the reactive movements of fish in response to a fishing line or other stimulus comprising:
An ultrasonic Doppler apparatus for detecting actively swimming fish or the reactive movements of fish in response to a fishing lure or other stimulus comprising:
Dependencies are inferred from the claim text.