Answers to Your Questions: What Is an FIR Filter?

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In summary, an FIR filter is a type of digital filter that uses previous input values to determine its output value. It can be designed to perform highpass, lowpass, or bandpass functions on digital data. It differs from an IIR filter, which has a memory and can have sharper filter functions but is more difficult to make stable.
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meldave00
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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
 
  • #3
Thanks. I appreciate it.
 

1. What is an FIR filter?

An FIR (Finite Impulse Response) filter is a type of digital filter used in signal processing to remove unwanted noise or alter the frequency response of a signal. It is called "finite" because its output depends only on a finite number of input samples, and "impulse response" because its response to an impulse signal is finite.

2. How does an FIR filter work?

An FIR filter works by convolving the input signal with a finite number of coefficients, also known as the impulse response. These coefficients are used to modify the amplitude of the input signal at each time step, resulting in a filtered output signal. The coefficients are carefully selected to achieve the desired frequency response.

3. What are the advantages of using an FIR filter?

Some advantages of FIR filters include their stability, linear phase response, and easy implementation in digital systems. They are also able to achieve a sharp cutoff in the frequency domain, making them useful for applications such as audio or image processing.

4. Are there any disadvantages of using an FIR filter?

One disadvantage of FIR filters is that they typically require a larger number of coefficients compared to other types of filters, which can lead to higher computational complexity. They also have a finite impulse response, meaning they cannot completely eliminate unwanted frequencies.

5. How are FIR filters different from other types of filters?

FIR filters differ from other types of filters, such as IIR (Infinite Impulse Response) filters, in that they have a finite impulse response and do not use feedback. This makes them easier to design and implement, but can also result in a longer filter length. FIR filters also have a linear phase response, meaning all frequency components of the signal experience the same delay.

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