A transducer assembly for imaging an underwater environment of a body of water, the transducer assembly comprising:
- at least one array of a plurality of transducer elements mounted to a watercraft on the body of water, wherein the at least one array of the plurality of transducer elements is oriented with an emitting face in a facing direction, wherein the facing direction is generally forward and downward of the watercraft,
- wherein the emitting face of the at least one array of the plurality of transducer elements defines a width and a length, wherein the length of the emitting face is greater than the width of the emitting face, and wherein the length of the emitting face extends in a fore-to-aft direction of the watercraft, wherein the facing direction is perpendicular to the emitting face,
- wherein each of the plurality of transducer elements defines a length and a width, wherein the length of each of the plurality of transducer elements is greater than the width of each of the plurality of transducer elements, wherein the length of each of the plurality of transducer elements is perpendicular to the length of the emitting face,
- wherein the plurality of transducer elements are configured to transmit one or more sonar beams into the underwater environment, and
- wherein the at least one array of the plurality of transducer elements is configured to operate each of the plurality of transducer elements at a fixed phase shift and vary in frequency so as to beamform multiple sonar return beams across the emitting face between a first range of angles in the fore-to-aft direction and between a second range of angles in the fore-to-aft direction, wherein the first range of angles is symmetrical to the second range of angles with respect to the facing direction, and wherein a gap of a third range of angles in the fore-to-aft direction separates the first range of angles and the second range of angles, wherein the first range of angles includes an angle that is substantially straight downward from the watercraft;
- an orientation sensor configured to determine an orientation of the array with respect to a top surface of the body of water;
- and
- a sonar signal processor in communication with the array and configured to:
- operate the array to cause the plurality of transducer elements to transmit the one or more sonar beams into the underwater environment;
- receive sonar return data from the plurality of transducer elements of the array;
- filter the sonar return data based on frequency to form the multiple sonar return beams;
- determine, based on data from the orientation sensor, a plurality of the multiple sonar return beams that correspond to a fourth range of angles in the fore-to-aft direction including the angle within the first range of angles that is substantially straight downward from the watercraft, wherein the plurality of the multiple sonar return beams form a beam shape that is defined by a fore-to-aft angle within a range of 10°-45° in the fore-to-aft direction and a port-to-starboard angle within a range of 10°-27° in a port-to-starboard direction, wherein the fore-to-aft angle is the fourth range of angles that corresponds to the determined plurality of the multiple sonar return beams;
- determine, based on the orientation data, one of the multiple sonar return beams that corresponds to the angle within the first range of angles that is substantially straight downward from the watercraft, wherein the one of the multiple sonar return beams form a fan-shaped beam that is defined by a fore-to-aft angle within a range of 0.5°-3° in the fore-to-aft direction and a port-to-starboard angle within a range of 10°-27° in the port-to-starboard direction, wherein the fore-to-aft angle is the angle within the first range of angles that corresponds to the determined one of the multiple sonar return beams;
- generate a first sonar image of the underwater environment forward and downward from the watercraft, wherein the first sonar image is a two-dimensional live sonar image that is formed of sonar return data from each of the multiple sonar return beams, and wherein the sonar return data used to form the two-dimensional live sonar image was received at substantially a same time by the plurality of transducer elements;
- generate a second sonar image of the underwater environment downward from the watercraft, wherein the second sonar image is formed from the determined plurality of the multiple sonar return beams that corresponds to the fourth range of angles, wherein the second sonar image is formed of a plurality of sonar image portions built up over time, wherein each of the plurality of sonar image portions corresponds to sonar return data from the determined plurality of the multiple sonar return beams received at different times;
- and
- generate a third sonar image of the underwater environment downward from the watercraft, wherein the third sonar image is formed from the determined one of the multiple sonar return beams that corresponds to the angle within the first range of angles that is substantially straight downward from the watercraft, wherein the third sonar image is formed of a plurality of sonar image portions built up over time, wherein each of the plurality of sonar image portions corresponds to sonar return data from the determined one of the multiple sonar return beams received at different times;
- and
- generate a fourth sonar image of the underwater environment downward from the watercraft, wherein the fourth sonar image is formed from both the determined plurality of the multiple sonar return beams that corresponds to the fourth range of angles and the determined one of the multiple sonar return beams that corresponds to the angle within the first range of angles that is substantially straight downward from the watercraft, wherein the fourth sonar image is formed of a plurality of sonar image portions built up over time, wherein each of the plurality of sonar image portions corresponds to sonar return data from both the determined plurality of the multiple sonar return beams and the determined one of the multiple sonar return beams.