14. An apparatus as defined in claim 10: A. in which said shift register contains a plurality of fields holding filter coefficients and at least one field holding an elapsed time; B. including means for applying a fixed number to said second adder input terminal when said time field is applied to said first adder input, thereby to change said elapsed time by a fixed amount on each recirculation of said shift register, and C. including means for detecting a predetermined value of said elapsed time.
10. An apparatus as defined in claim 2 in which said coefficient integrator and storage means includes: A. a shift register having an input end and an output end; B. an adder having first and second input terminals and providing an output that is the sum of the inputs applied to its input terminals; C. means applying the adder output to the input end of the shift register; D. a first gate for selectively connecting the output end of said shift register to the first input terminal of the adder, and E. a second gate for selectively applying an input to the second input terminal of the adder.