Electronic filter for noisy analogue signals - transmits all step changes and large signals without delay

摘要

The filter consists of a first order delay network followed by a difference unit which gives the difference of the delayed signal and the input signal. The difference signal is then passed through a non-linear network, which may consist of antiparallel diodes and resistors, followed by a summing unit. The filter output gives the sum of the non-linear difference signal and the delayed input signal. The non-linear network has a true dead-zone with zero transmission of very low signals. The output amplitude is the same as the input signal amplitude. The filter is thus suitable for control with a short time constant where a normal delay filter would be unsuitable. It allows meters and recorders to give a more stable indication and reduces the demand on actuators.