Is a sequence of numbers, so-called samples, where every sample lasts T s seconds. The time T s is called sampling period and the number produced in the n -th sampling period (i.e., after n times T s seconds) is denoted as x ( nT s ). The values x ( nT s ) are constrained to belong to a finite set of possibilities (for example, in a 1-bit signal, these values are just 0 or 1). Additionally, it is usual to consider that x ( nT s ) = 0 for negative values of n . For analysis purposes, it is usual to consider T s = 1.
Published in Chapter:
Comb Filters Characteristics and Current Applications
Copyright: © 2018
|Pages: 12
DOI: 10.4018/978-1-5225-2255-3.ch522
Abstract
The comb filter is a very popular linear-phase filter due its simplicity, i.e. all its coefficients are equal to unity. As a consequence, it does not require multipliers or coefficients storage. This characteristic makes this filter attractive for many applications, as for example, in decimation, communications, digital audio, among others. However, the comb filter presents passband droop and a poor attenuation in the stopband region. In this proposal, the comb filter characteristics are reviewed and illustrated with one example. Additionally, the selected methods commonly used to improve the magnitude characteristics of a comb filter will be described and illustrated with examples.