Fish finder

Claim 1

AN APPARATUS FOR LOCATING OBJECTS MOVING BENEATH THE SURFACE OF THE WATER, A PORTABLE INSTRUMENT FOR IMMERSION BENEATH THE SURFACE OF THE WATER TO TRANSMIT PRESSURE WAVES TO THE WATER AND RECEIVE PRESSURE WABES REFLECTED FROM OBJECTS IN THE WATER COMPRISING A BODY OF INSULATING MATERIAL AND A PAIR OF RECESSES FORMED IN SAID BODY AND EXTENDING FROM AN OUTER SURFACE THEREOF, A PAIR OF DIRECTIONAL TRANSDUCERS DISPOSED WITHIN SAID RECESSES SO THAT THE DIRECTIONAL AXES OF SAID PAIR OF DIRECTIONAL TRANSDUCERS ARE SUBSTANTIALLY PARALLEL TO EACH OTHER AND NORMAL TO SAID OUTER SURFACE, SEALING MEANS COVERING THE OPENINGS OF SAID RECESSES AT SAID OUTER SURFACE AND SUFFICIENTLY PLIABLE TO TRANSMIT PRESSURE WAVES BETWEEN THE WATER IN WHICH SAID INSTRUMENT IS IMMERSED AND SAID TRANSDUCERS, ELECTRODES ENGAGING THE OPPOSITE SURFACES OF SAID TRANSDUCERS AND CONNECTED TO CONDUCTORS EXTENDING THROUGH THE BOTTOM WALLS OF SAID RECESSES RESPECTIVELY CONNECTED TO TRANSMITTER AND RECEIVING DEVICES AND SAID PAIR OF TRANSDUCERS BEING SO ARRANGED AND CONNECTED TO SAID CONDUCTORS THAT ONE OF SAID TRANSDUCERS IS ELECTRICALLY EXCITED TO VIBRATE MECHANICALLY AND THE OTHER TRANSDUCER IS MECHANICALLY EXCITED BY REFLECTED PRESSURE WAVES TO GENERATE AN ELECTRICAL PORTENTIAL INDEPENDENT OF THE ELECTRICAL EXCITATION OF SAID ONE TRANSDUCER.

Claim 2

A METHOD FOR DETECTING THE PRESENCE OF FISH AND OTHER MOVING OBJECTS SUBMERGED IN WATER WHICH COMPRISES TRANSMITTING CONTINUOUS CONSTANT FREQUENCY PRESSURE WAVES IN A DIRECTIONAL PATTERN FROM A SOURCE BENEATH THE SURFACE OF THE WATER, SCANNING THE DIRECTIONAL PATTERN IN AZIMUTH, RECEIVING AT A POINT ADJACENT SAID SOURCE THE PRESSURE WAVES REFLECTED FROM THE INTERACTION BETWEEN THE TRANSMITTED CONSTANT FREQUENCY PRESSURE WAVES AND RADIATED PRESSURE WAVES INDUCED BY THE MOVING OBJECT, AND PROVIDING AN INDICATION OF ANY DIFFERENCE BETWEEN THE FREQUENCIES OF THE RECEIVED REFLECTIONS AND THE TRANSMITTED PRESSURE WAVES TO REVEAL THE PRESENCE OF A MOVING OBJECT IN THE DIRECTION OF THE PATTERN AT THE TIME OF THE INDICATION OF THE DIFFERENCE IN SAID FREQUENCIES.