Low Pass Filter

Low Pass Filter
Like all filters, the low pass filter is designed to let some things through but not others. The principle behind low pass filters is to preserve or even amplify signals with frequencies below a certain point. This point is known as the corner frequency and is located at the point where the gain is -3db.

A low pass filer with a corner frequency of 500Hz would maintain a signal of 200hz but would block a signal with a frequency of 600hz.

Examples
There are two types of filters: analog and digital. The two filters work in fundamentally different ways. The analog filter actually changes the signal depending on frequency, where as the digital filter uses different sample rates to filter unwanted data.

Analog Filters
There are two types of analog filters passive, and active. The passive filter uses discrete components to degrade signals of unwanted frequencies. The active filters change the amplification of the signal depending on its frequency.