The Moving Average - Band Pass Filter

The bandpass is the most powerful of the filter types we can exploit using the simple moving average. Learn how to design your own bandpass in this article

A noisy signal has the component of 100 wavelength extracted via a bandpass filter (yellow) created with simple moving averages (low pass filters, in green).

What is a Band Pass Filter?

In signal processing and the related topic of time-series filtering we often hear the terms ‘low pass filter’, ‘high-pass filter’, ‘band pass filter’ or ‘band stop filter’. They each refer to the process of creating a new signal with part of the original signal removed, or ‘filtered’. In the case of the high pass filter we remove the lower frequency components from a signal and retain the higher frequencies; we allow the higher frequencies to pass. This was achieved in the previous article with the help of a moving average - a particular type of low pass filter when plotted correctly to account for the digital filter lag. When the filtered (low passed) signal was subtracted from the original signal all that remained of the original signal were components above the cutoff (the span, or period) of the low …