System which cooperatively uses a systolic array processor and auxiliary processor for pixel signal enhancement

A lofargram enhancement system comprising:

• a systolic processor having 1 to j rows and 1 to i columns of processing elements, the range of j corresponding to the number of pixels to be displayed on each scan of a recorder stylus, each processing element having a location corresponding to its respective i-j index, each processing element having a computational capability and having memory means for storing a pixel intensity value, a row average value and a column average value;
• means, including said systolic processor, for receiving a scan line of digitized sonar data comprising a sequence of pixel intensity signal values from an acoustic signal source, each respective pixel intensity signal value characterizing a signal amplitude at a corresponding row and column location and said processor storing each respective received pixel intensity signal value in the respective row 1 location;
• program means including processor elements for calculating a row total value for the pixel intensity signal values stored in a predetermined relational row array of processing elements and for calculating a column total value for the total of the pixel intensity signal values stored in a predetermined relative column array for each respective processing element in the systolic processor;
• an auxiliary processor for reading the respective row total and column total for each processing element in the jth column of the systolic processor and for scaling the pixel intensity value and for calculating the difference between the row total and the scaled pixel intensity value for each processing element in the jth column, and for determining if the difference between the row total and the scaled pixel intensity value exceeds a predetermined threshold, and if the difference exceeds the predetermined threshold, deciding if the difference is positive, and if the difference is positive, loading the corresponding first column processing element with a corrected pixel value, and with the average row value and the average column value from the corresponding jth column processing element, the corrected pixel values being selected from a table correlating corrected pixel value to calculated difference value;
• a FIFO;
• and,
• BIN selection and timing and control circuit means for right shifting the contents of the processing elements within the entire systolic processor j times and if not, for right shifting the systolic array one column to the right and actuating the auxiliary processor means to again calculate and enter corrected pixel values in each first column processing element and if the systolic processor has been right shifted j times, for shifting the contents of the bottom row of corrected pixel values into said FIFO for delivery to a recorder as a scan line of data, and for shifting the contents of all corrected pixel values, row averages and column averages stored in the respective processing elements down one row, and for commanding the means for receiving the next scan line of data to receive the next scan line of data.

A sonar signal enhancement process comprising the steps of:

• (A) receiving, in an input FIFO, a scan line of data comprising a sequence of pixel intensity digital signal values from an acoustic signal processing source, each respective pixel intensity signal value characterizing a signal amplitude at a BIN location;
• (B) storing each pixel intensity signal in a processing element in an array of processing elements comprising a systolic processor, each processing element having a location corresponding to a BIN location within the scan line of data received, the systolic processor being arranged into i rows and j BINS, or columns, of processing elements, the processing elements in the jth column being the rightmost column of processing elements, the range of j including the number of pixels to be enhanced and displayed on each scan of a recorder stylus;
• (C) concurrently calculating a row total value for the total of the pixel intensity signal values stored in a predetermined relationally related row array for each respective processing element and calculating a column total value for the total of the pixel intensity signal values stored in a predetermined relationally related column array for each respective processing element in the systolic processor;
• (D) reading the respective row total and column total for each processing element in the rightmost column of the systolic processor with an auxiliary processor, and calculating the difference between the row total and the column total for each processing element, and determining if the difference exceeds a predetermined threshold, and if the difference crosses the threshold, deciding if the difference is positive, and if the processing element value difference is positive deciding that the processing element location contains a corrected pixel value, the corrected pixel values being selected from a table correlating corrected pixel value to calculated difference value, the corrected pixel values being stored back into the pixel intensity signal value for the corresponding processing element;
• (E) determining if the systolic processor has been right shifted j times and if not, right shifting the systolic array one column to the right and repeating step (D), and if the systolic processor has been right shifted j times, shifting the contents of the bottom row of corrected pixel values out to the right into a FIFO for delivery to a recorder as a scan line of data, and shifting the contents of all corrected pixel values, row averages and column averages stored in the respective processing elements down one row, preparatory to receiving the next scan line of data and repeating step (A).