Filter for separation of two frequency spectra - has resistances of RC filter sections switched between two values at high frequency

摘要

The spectra are found in the output signal of a measurement sensor of a surface testing instrument. The filter comprises at least one RC section with adjustable pass-band. The resistance of the RC filters (8, 9, 18, 36) can be switched between two values at a frequency higher than the frequency to be separated. Switching-on times of the two resistances, determining the filter (8, 9, 18, 36) cutt-off frequency are adjustable.