. . "?? dec 2 [ k ] = ( 1 M ) ??? i = 0 M - 1 ( y [ m + i ] - d [ m + i ] ) 2 ( 19 ) where k is a block index, symbol index base m=(k???1)M, y is the equalizer output, d is the zero delay output of the trellis decoder 928, and M is a selected block size." . .