Beamforming sonar system with improved sonar image functionality, and associated methods

A system for imaging an underwater environment of a body of water, the system comprising:

• a single array of a plurality of transducer elements mounted to a watercraft on the body of water and 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 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 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 each of the plurality of transducer elements are configured to operate at a fixed phase shift and vary in frequency so as to beamform multiple sonar return beams between a first range of angles in the fore-to-aft direction and 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;
• 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;
• generate a sonar image of the underwater environment downward from the watercraft by:
• determining one of the multiple sonar return beams that corresponds to an angle within the first range of angles that is substantially straight downward from the watercraft, wherein the determined one of the multiple sonar return beams forms a fan-shaped beam that is relatively narrow in the fore-to-aft direction and relatively wide in a port-to-starboard direction;
• determining a plurality of the multiple sonar return beams that corresponds to a fourth range of angles in the fore-to-aft direction including at least the angle within the first range of angles that is substantially straight downward from the watercraft, wherein the determined plurality of the multiple sonar return beams form a beam shape that is relatively wide in both the fore-to-aft direction and the port-to-starboard direction;
• forming the sonar image from both the one of the multiple sonar return beams and the plurality of the multiple sonar return beams, wherein the sonar image is formed from:
• a plurality of first sonar image portions that corresponds to sonar return data from the one of the multiple sonar return beams received at different times, wherein the plurality of first sonar image portions are built up over time;
• and
• a plurality of second sonar image portions that each correspond to a fish arch generated from the plurality of multiple sonar return beams, wherein the plurality of second sonar image portions are positioned within the plurality of first sonar image portions so as to correspond to a depth and a time associated with sonar return data taken from the plurality of multiple sonar return beams.

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 and 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 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 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 each of the plurality of transducer elements are configured to operate at a fixed phase shift and vary in frequency so as to beamform multiple sonar return beams between a first range of angles in the fore-to-aft direction and 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;
• 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;
• generate a sonar image of the underwater environment downward from the watercraft by:
• determining one of the multiple sonar return beams that corresponds to an angle within the first range of angles that is substantially straight downward from the watercraft, wherein the determined one of the multiple sonar return beams forms a fan-shaped beam that is relatively narrow in the fore-to-aft direction and relatively wide in a port-to-starboard direction;
• determining a plurality of the multiple sonar return beams that corresponds to a fourth range of angles in the fore-to-aft direction including at least the angle within the first range of angles that is substantially straight downward from the watercraft, wherein the determined plurality of the multiple sonar return beams form a beam shape that is relatively wide in both the fore-to-aft direction and the port-to-starboard direction;
• forming the sonar image from both the one of the multiple sonar return beams and the plurality of the multiple sonar return beams, wherein the sonar image is formed from:
• a plurality of first sonar image portions that corresponds to sonar return data from the one of the multiple sonar return beams received at different times, wherein the plurality of first sonar image portions are built up over time;
• and
• a plurality of second sonar image portions that each correspond to a fish arch generated from the plurality of multiple sonar return beams, wherein the plurality of second sonar image portions are positioned within the plurality of first sonar image portions so as to correspond to a depth and a time associated with sonar return data taken from the plurality of multiple sonar return beams.