68 the graph b in fig8 illustrates the lma signal prior entering the amplifier 76 the two paths containing the shift registers 72 74 produce time shifted facsimiles of the lma signal shown respectively in graph a and graph c in fig8 the shift register 72 delays the signal by the distance u03b4 relative to the lma signal in graph b to produce the graph a and the shift register 74 delays the signal by the distance 2 u03b4 relative to the lma signal in graph b to produce the signal of graph c both shifted signals are then scaled in a multiplier 76 or 78 by the factor u03b1 which reduces the amplitude of the primary signal 68 to the amplitude of the echo signals 68 a 68 b and the amplitude of the echo signals to insignificant values the scaled signals are shown in graphs d and e of fig8 as indicated in fig9 the scaled and time shifted signals are then subtracted from the total lma signal at the summing junction 80 which causes the scaled echo signals 68 a 68 b to essentially be insignificant in an enhanced lma signal at the output of the summing junction as illustrated in graph f of fig8 as shown the enhanced lma signal of graph f has a slightly attenuated primary signal 68 e and mere vestiges 68 f 68 g of the echo signals if the vestiges 68 f 68 g were significant the enhanced lma signal could be processed a second time through another algorithm such as shown in fig9 for a further reduction in significance the enhanced lma signal produced by the.