Side-looking fish finder
First Claim
1. A method of detecting fish in a body of water, comprising the steps of:
- transmitting a sound pulse through the water in a predetermined direction, thereafter detecting echoes from said sound pulse which are each preceded by a leading space interval free of other echoes and followed by a trailing space interval free of other echoes, rejecting each said detected echo which has a duration falling outside a predetermined range bounded by an upper limit and a lower limit, accepting said detected echoes other than said detected echoes rejected in said rejecting step, and interpreting each said accepted echo to be an echo from a fish.
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Accused Products
Abstract
A side-looking fish finding apparatus transmits a sonar pulse approximately horizontally into a body of water, and then monitors echoes from the pulse. The time interval between successive sonar pulses is varied in a random manner in order to permit two or more similar units to be used in close proximity to each other without significantly interfering with each other. An individual echo is treated as the detection of a fish if it has a magnitude above a predetermined threshold, if it has a length within a predetermined range bounded by upper and lower limits, if it is preceded by a leading space interval free of other echoes and having a predetermined duration, if it is followed by a trailing space interval free of other echoes and having a predetermined duration, the duration of the trailing space interval being less than the duration of the leading space interval, and if an equivalent echo is received in response to each of the next four successive sonar pulses.
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Citations
59 Claims
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1. A method of detecting fish in a body of water, comprising the steps of:
- transmitting a sound pulse through the water in a predetermined direction, thereafter detecting echoes from said sound pulse which are each preceded by a leading space interval free of other echoes and followed by a trailing space interval free of other echoes, rejecting each said detected echo which has a duration falling outside a predetermined range bounded by an upper limit and a lower limit, accepting said detected echoes other than said detected echoes rejected in said rejecting step, and interpreting each said accepted echo to be an echo from a fish.
- View Dependent Claims (2, 3, 55, 56)
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4. A method of detecting fish in a body of water, comprising the steps of:
- transmitting a sound pulse through the water in a predetermined direction, thereafter detecting echoes from said sound pulse which are each preceded by a leading space interval free of other echoes and followed by a trailing space interval free of other echoes, rejecting each said detected echo for which said trailing space interval is less than a predetermined trailing time duration.
- View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 17, 18, 22, 23, 24, 25, 26, 27, 28, 29)
- 13. A method of detecting objects in a body of water, comprising the steps of periodically transmitting a pulse of sound in a predetermined direction and thereafter monitoring echoes of the sound reflected from objects in the water, and substantially randomly varying the length of a time interval between successive said transmitting steps.
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19. A method of detecting fish in a body of water, comprising the steps of:
- emitting a sound pulse into said body of water, detecting echoes from said sound pulse and normalizing magnitudes thereof based on distances traveled through the water, comparing the normalized magnitude of each said echo to a reference magnitude which is a minimum normalized magnitude produced by a fish of interest, rejecting echoes having normalized magnitudes below said reference magnitude, and accepting other echoes;
wherein said emitting step includes the step of directing said sound pulse in an approximately horizontal direction; and
wherein an approximately horizontally extending bottom surface below said body of water produces an echo which, after said normalizing step, has a normalized magnitude which is less than said reference magnitude.
- emitting a sound pulse into said body of water, detecting echoes from said sound pulse and normalizing magnitudes thereof based on distances traveled through the water, comparing the normalized magnitude of each said echo to a reference magnitude which is a minimum normalized magnitude produced by a fish of interest, rejecting echoes having normalized magnitudes below said reference magnitude, and accepting other echoes;
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20. A method of detecting fish in a body of water, comprising the steps of:
- periodically transmitting a sound pulse through the water in a predetermined direction;
thereafter detecting echoes from said sound pulse and normalizing magnitudes thereof based on distances traveled through the water;
thereafter selecting echoes which have normalized magnitudes above a reference magnitude equal to a minimum normalized magnitude produced by a fish of interest and which are each preceded by a leading space interval free of other echoes and followed by a trailing space interval free of other echoes;
rejecting each said selected echo which has a duration falling outside a predetermined range bounded by an upper limit and a lower limit, said rejecting step including the steps of rejecting each said selected echo for which said trailing space interval is less than a first predetermined time duration and rejecting each said selected echo for which said leading space interval is less that a second predetermined time duration, said second predetermined time duration being greater than said first predetermined time duration;
accepting said selected echoes other than said selected echoes rejected in said rejecting step;
maintaining an echo buffer having a plurality of records, and saving in a respective said record of said echo buffer for each said accepted echo a value representing a distance to an object which produced the echo;
maintaining a correlation buffer having a plurality of records which each include a distance value and a count value;
comparing each said distance value in said echo buffer to said distance values in said correlation buffer;
incrementing the correlation count in each of said records in said correlation buffer for which the distance value therein differs form one of said distance values in said echo buffer by less than a predetermined amount;
zeroing the correlation count in each of said records in said correlation buffer for which the distance value therein differs from each of said distance values in said echo buffer by more than said predetermined amount; and
producing an operator perceptible indication that a fish has been detected when one of said correlation counts is greater than a predetermined value. - View Dependent Claims (21)
- periodically transmitting a sound pulse through the water in a predetermined direction;
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30. A method of detecting fish in a body of water, comprising the steps of:
- transmitting a sound pulse through the water in a predetermined direction, thereafter detecting echoes from said sound pulse which are each preceded by a leading space interval free of other echoes and followed by a trailing space interval free of other echoes, and rejecting each said detected echo for which said leading space interval is less than a predetermined leading time duration.
- View Dependent Claims (31, 32, 33, 34, 35, 36, 54, 57)
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37. A method of detecting fish in a body of water, comprising the steps of:
- transmitting a sound pulse through the water in a predetermined direction, thereafter detecting echoes from said sound pulse which are preceded by a leading space interval free of other echoes and followed by a trailing space interval free of other echoes, rejecting each said detected echo which has a duration greater than a predetermined upper limit, accepting said detected echoes other than said detected echoes rejected in said rejecting step, and interpreting each said accepting echo to be an echo from a fish.
- View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 58, 59)
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48. An apparatus for detecting fish in a body of water, comprising:
- first means for transmitting a sound pulse through the water in a predetermined direction;
second means for detecting echoes from said sound pulse and for accepting each said echo representative of a fish; and
display means responsive to said second means for selectively providing an operator perceptible indication of a detected fish, said display means including means defining an image of a substantially conical region representative of divergence of said sound pulses in said predetermined direction in said water, said conical region having an apex portion representative of a location of said first means, said display means further including means responsive to said second means for selectively displaying within said conical region said operator perceptible indication of a detected fish. - View Dependent Claims (49, 50, 51, 52, 53)
- first means for transmitting a sound pulse through the water in a predetermined direction;
Specification