From Helmut Zarzycki
Munich, Germany
You state that “background noise…can actually make it easier to pick
up faint signals”, and add “This extraordinary idea emerged in 1981.” (“Noises
on”, 1 June, p 28).
Well, in the field of control circuitry engineering, this knowledge was put
to good use much earlier, when technicians introduced “dither” signals into
control loops to lower their response thresholds. In other words, they increased
the overall system sensitivity by adding an artificial background noise to an
otherwise clean signal.
