You are combining two concepts.
A sensor is any device that responds to a desired signal in some manner to produce an output that is used to detect the presence of the desired signal or to allow some desired attribute of the signal to be measured - such as its amplitude, frequency, rate of change, relative phase, etc. Even colour, temperature, dimensions, current/voltage/power ... .
The terms low-pass and band-pass relate to the processing of a sensed signal so that only a portion of the signal is used to provide the sensor output. It may seem counter intuitive to ignore part of a signal, but this is useful when the signal may be accompanied noise or by other interfering or unwanted signals.
A sensor is any device that responds to In the above context, a desired signal in some manner to produce an output thatlow-pass sensor is useda sensor, intended to detect the presence of the desiredor measure a specific signal or to allow some desired attributecondition, that accepts the lower frequency components of the signal to be measured but rejects input above a selected frequency. A band- such as its amplitudepass sensor is one which processes only signals with frequencies within a given range of frequencies, and rejects signal higher or lower in frequency, rate than the selected band of change, relative phase, etcfrequencies.
The terms low-pass and band-passAs examples: relate
A low pass sound sensor may be a microphone plus amplifier plus a filter set to exclude frequencies above say 4000 Hz. Such a sensor would respond to speech signals and the processingfundamental sounds of a sensed signal somany musical instruments but would not be affected by high frequency noise signals.
A bandpass doppler radar may have the range of frequencies that onlyit acts on limited to a portionrange of the signal is usedDoppler frequencies corresponding to providevelocities from the sensor outputspeed of a person walking slowly up to about 100 mph. It may seem counter intuitivewould therefore tend to ignore part ofsignals from eg a signal, but this is useful when the signal may be accompanied noise or by other interferingdoor being very slowly closed (V << walking speed) or unwantedto signals from reflections from aircraft (V > 100 mph).
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