FILTER

摘要

In a filter, filter input signals (u(t)) are modulated on a carrier signal (p(t)) with a carrier frequency (fo) via a multiplier (M1) and taken to an input (E1) of a SAW convolver (C). A sine-wave signal (v(t)) with a predeterminable frequency is also modulated on the carrier signal (p(t)) via a second multiplier (M2) and taken to a second input (E2) of the convolver (C). The output signal (A) of the convolver (C) represents the folding product of the input signals. The sine-wave input signal (v(t)) is taken via a retarder (VZ) to an input (5) of a further multiplier (M4) which also receives at its input the synchronously demodulated output signal (g(t)) of the convolver (C). The filter has a band pass characteristic with a very rapidly variable median frequency in wide ranges.