US4081783A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fish finder capable of discriminating sizes of fish
Assignee: Individual
•
Filing: 1976-09-22
•
Granted: 1978-03-28
•
Expires: 1996-09-22
Abstract
Abstract The present invention discloses a fish finder wherein one transducer is used to generate both high- and low-frequency ultrasonic waves which are simultaneously emitted and the electrical signal representative of the reflected high- or low-frequency ultrasonic waves is extracted by the signal representative of the reflected low- or high-frequency ultrasonic waves, thereby discriminating the sizes of fish detected.
Inventors
- 👤 Keisuke Honda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:56
CPC Classifications
G; G01; G01S; G01S15/00; G01S15/88; G01S15/96; G01S15/02; F; F02; F02B; F02B75/00; F02B75/02; F02B2075/022; F02B2075/025
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
116 words
A fish finder capable of discriminating the sizes of fish, comprising: a single transducer capable of transmitting and receiving high- and low-frequency ultrasonic sound waves simultaneously, one of said high- and low-frequency ultrasonic sound waves being emitted with a wide beam angle while the other of said waves is emitted with a narrow beam angle; receivers for processing the high- and low-frequency echo signals received by said transducer, a subtractor circuit for subtracting the received echo signal corresponding to the narrow beam angle from the received echo signal corresponding to the wide beam angle, and a recorder for recording the output from said subtractor circuit comprising echo signals corresponding to images of fish of desired size.
Claim 2
Dependent Claim
116 words
A fish finder capable of discriminating the sizes of fish, comprising: a single transducer capable of transmitting and receiving high- and low-frequency ultrasonic sound waves simultaneously, one of said high- and low-frequency ultrasonic sound waves being emitted with a wide beam angle while the other of said waves is emitted with a narrow beam angle; receivers for processing the high- and low-frequency echo signals received by said transducer, a subtractor circuit for subtracting the received echo signal corresponding to the narrow beam angle from the received echo signal corresponding to the wide beam angle, and a recorder for recording the output from said subtractor circuit comprising echo signals corresponding to images of fish of desired size.
Claim 3
Dependent Claim
61 words
A fish finder as set forth in claim 1 wherein the high-frequency ultrasonic sound waves are emitted at a narrow beam angle while the low-frequency ultrasonic waves are emitted at a wide beam angle; and the reflected low-frequency ultrasonic sound waves are subtracted from the reflected high-frequency ultrasonic sound waves, thereby discriminating individual fish and schools of fish of small size.
Claim 4
Dependent Claim
113 words
A fish finder capable of discriminating the sizes of fish, comprising: a single transducer capable of transmitting and receiving high- and low-frequency ultrasonic sound waves simultaneously, receivers for processing the high- and low-frequency signals received by said transducer, a subtractor circuit for subtracting one of said received high- and low-frequency signals from the other of said signals, means for determining when the received low-frequency signal has an amplitude exceeding a predetermined threshold value, and for thereupon detecting and differentiating said received signal and adding the resulting detected and differentiated signal to the output of the subtractor circuit to provide a signal enhancing the sea bottom, and a recorder for recording said enhanced signal.
Claim 5
Dependent Claim
113 words
A fish finder capable of discriminating the sizes of fish, comprising: a single transducer capable of transmitting and receiving high- and low-frequency ultrasonic sound waves simultaneously, receivers for processing the high- and low-frequency signals received by said transducer, a subtractor circuit for subtracting one of said received high- and low-frequency signals from the other of said signals, means for determining when the received low-frequency signal has an amplitude exceeding a predetermined threshold value, and for thereupon detecting and differentiating said received signal and adding the resulting detected and differentiated signal to the output of the subtractor circuit to provide a signal enhancing the sea bottom, and a recorder for recording said enhanced signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-03-27 | 1981-09-26 | 1982-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-03-27 | 1985-09-26 | 1986-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-03-27 | 1989-09-26 | 1990-03-28 | $7700.00 | Window Closed / Lapsed |