Sonar apparatus having a steerable beam

A method in a sonar apparatus for finding a relative location of a bottom surface, the method including steps of:

• issuing steering information to a scanning transducer for steering an acoustical beam;
• receiving information for a distance to said bottom surface from said scanning transducer from a reflection of said acoustical beam from said bottom surface;
• resolving said distance into a first distance to said bottom surface representative of a depth and a second distance to said bottom surface orthogonal to said first distance
• displaying a history of said depth on a first screen with a first scale and simultaneously displaying a current said depth on a second screen with said first scale, where said first scale on said second screen is adjacent and aligned to said first scale on said first screen, and a current said second distance on said second screen on a second scale orthogonal to said first scale in a visual form that is perceptible to a user.

A sonar apparatus having a steerable acoustical beam, the sonar apparatus comprising:

• a control circuit for providing steering information to a scanning transducer for scanning said acoustical beam, receiving distance determination information for a distance to an object, and resolving said distance determination information into a downward distance and a second distance orthogonal to said downward distance;
• a receiver having a variable sensitivity for receiving a signal indicative of said distance to said object from said scanning transducer from a reflection of said acoustical beam from said object including a bottom surface and providing said distance determination information to said control circuit;
• a display having a first full-scale range and a second full-scale range, the display coupled to the control circuit for displaying a representation of said object at a display location that corresponds to said downward distance as a proportion of said first full-scale range and said second distance as a proportion of said second full-scale range;
• and
• an autorange control coupled to the display for adjusting said first and said second full-scale ranges in the same ratio for increasing a ratio of said sensitivity to said reflection from a far away said object represented on the display to said sensitivity to said reflection from a near said bottom surface represented on the display.

A method in a sonar apparatus for finding a relative location of an object, the method including steps of:

• issuing a transmit signal to a scanning transducer for transmitting an acoustical beam;
• receiving a receive signal from said scanning transducer with a receiver having a selectable sensitivity to said receive signal, said receive signal including information for a distance to an object including a bottom surface from a reflection of said acoustical beam from said object;
• resolving said distance into a downward distance and a forward distance orthogonal to said downward distance;
• displaying a representation of said object on a display with said downward distance represented on a first scale having a first full-scale range and said forward distance represented on a second scale having a second full-scale range;
• determining when said object is said bottom surface;
• and
• increasing a ratio between a first said sensitivity to a first said reflection corresponding to a far away said object represented on said display and a second said sensitivity to a second said reflection corresponding to a near said bottom surface represented on said display by increasing said first and second full-scale ranges in the same proportion when said downward distance to said bottom surface is a large proportion of said first full-scale range.

A marine sonar system having a steerable acoustical beam, the system comprising:

• a boat;
• a scanning transducer mounted to the underside of the boat for converting an electrical transmit signal having steering information into an acoustical beam having a selected direction in response to said steering information and converting a reflection of said acoustical beam from at least one object into an electrical receive signal;
• a control circuit coupled to the scanning transducer for issuing said electrical transmit signal, receiving said electrical receive signal, and calculating a distance to said object;
• and
• a scan control for receiving information for a directly selected scan center direction and a directly selected scan width and coupled to the control circuit for providing said steering information based upon said scan center direction and said scan width for automatically scanning said acoustical beam over said scan width about said center scan direction.

A method in a sonar apparatus for finding a relative location of an object, the method including steps of:

• receiving information for a directly selected scan width and a directly selected center scan direction;
• generating steering information in response to said scan width and said scan center direction;
• and
• issuing a transmit signal including said steering information to a scanning transducer for scanning an acoustical beam over said scan width about said center scan direction.