There are a few terms used to describe the behavior and performance of FIR filter including the following:
Filter Coefficients
The set of constants, also called tap weights, used to multiply against delayed sample values. For an FIR filter, the filter coefficients are, by definition, the impulse response of the filter.
Impulse Response
A filter’s time domain output sequence when the input is an impulse. An impulse is a single unity-valued sample followed and preceded by zero-valued samples. For an FIR filter the impulse response of a FIR filter is the set of filter coefficients.
Tap
The number of FIR taps, typically N, tells us a couple things about the filter. Most importantly it tells us the amount of memory needed, the number of calculations required, and the amount of "filtering" that it can do. Basically, the more taps in a filter results in better stopband attenuation (less of the part we want filtered out), less rippling (less variations in the passband), and steeper rolloff (a shorter transition between the passband and the stopband).
Multiply-Accumulate (MAC)
In the context of FIR Filters, a "MAC" is the operation of multiplying a coefficient by the corresponding delayed data sample and accumulating the result. There is usually one MAC per tap..
Filter Coefficients
The set of constants, also called tap weights, used to multiply against delayed sample values. For an FIR filter, the filter coefficients are, by definition, the impulse response of the filter.
Impulse Response
A filter’s time domain output sequence when the input is an impulse. An impulse is a single unity-valued sample followed and preceded by zero-valued samples. For an FIR filter the impulse response of a FIR filter is the set of filter coefficients.
Tap
The number of FIR taps, typically N, tells us a couple things about the filter. Most importantly it tells us the amount of memory needed, the number of calculations required, and the amount of "filtering" that it can do. Basically, the more taps in a filter results in better stopband attenuation (less of the part we want filtered out), less rippling (less variations in the passband), and steeper rolloff (a shorter transition between the passband and the stopband).
Multiply-Accumulate (MAC)
In the context of FIR Filters, a "MAC" is the operation of multiplying a coefficient by the corresponding delayed data sample and accumulating the result. There is usually one MAC per tap..
Transition Band
The band of frequencies between passband and stopband edges. The narrower the transition band, the more taps are required to implement the filter. (A "small" transition band results in a "sharp" filter.)
Delay Line
The set of memory elements that implement the "Z^-1" delay elements of the FIR calculation.
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