Answers to Your Questions: What Is an FIR Filter?

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An FIR (Finite Impulse Response) filter is a type of digital filter that generates its output based solely on a finite number of previous input values. It allows for the design of various filtering functions, such as highpass, lowpass, or bandpass, by customizing the polynomial calculations used in the filter. Unlike IIR (Infinite Impulse Response) filters, which depend on both past input and output values, FIR filters do not have memory, meaning their output is limited to a specific time window. While IIR filters can achieve sharper frequency responses, they are more complex and less stable than FIR filters. Understanding FIR filters is essential for applications in signal processing and digital communications.
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Can someone explain to me in leyman's terms what an FIR filter is and what it is used for?
 
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A finite impulse response filter is one form of a digital filter. It bases its output value at each clock tick on the input values that it has seen over some previous amount of time (like the last 10 clock ticks, for example). You can design the polynomial calculation that the filter is using for its input --> output function so that you perform a highpass, lowpass or bandpass function on the digital data.

FIR filters are contrasted with infinite impulse response filters (IIR), where the output is dependent on the input data stream, and also dependent on previous output values. It's like the IIR filter has some memory, which means that a single impulse at the input can cause the IIR output to keep on changing forever. IIR filters can have sharper skirts on their filter function compared to FIR filters, but they are also harder to make stable.

Here's a related wikipedia article FYI:

http://en.wikipedia.org/wiki/Digital_filter
 
Thanks. I appreciate it.
 

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