Digital filter design method and device, digital filter design program, and digital filter

Abstract

A symmetric unit filter (L10') is designed by combining in series two unit filters (1L10, 2L10) having asymmetric numerical sequences as filter coefficients (H1 to H3 and H4 to H6). Thus, by designing a filter by series connection, it is possible to automatically obtain a desired digital filter coefficient only by combining one type of unit filter (L10') in series. Moreover, a symmetric numerical sequence {-1, 0, 9, 16, 9, 0, -1}/32 is divided at the center into two parts and one of them is used as the asymmetric filter coefficients (H1 to H3 and H4 to H6). This reduces the number of necessary taps, eliminates use of a window function, and prevents generation of a discretization error in the filter characteristic obtained.

Description

technical field [0001] The present invention relates to a design method and device of a digital filter, a program for designing a digital filter, and a digital filter, in particular to a delay line with taps composed of a plurality of delayers, and the signals of each tap are transformed into After several times, the FIR filter and its design method are output after addition. Background technique [0002] Some kind of digital signal processing is often performed inside various electronic devices used in various fields such as communication, measurement, audio, video signal processing, medical treatment, and seismology. Among the most important basic operations of digital signal processing, there is filtering processing to extract only necessary signals in a certain frequency band from an input signal mixed with various signals or noise. Therefore, digital filters are often used in electronic equipment that performs digital signal processing. [0003] As a digital filter, a...

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Problems solved by technology

[0008] However, since the frequency characteristic of the filter obtained by the existing design method depends on the window function or the Chebyshev approximation, if it is not properly set, it is impossible to obtain a good frequency characteristic

However, it is generally difficult to properly set the window function and approximation

That is, in the above-mentioned existing filter design method, skilled technicians need a lot of time and effort to design, causing the comparatively inconvenient problem of designing an FIR filter with required characteristics.

[0009] Furthermore, even if it is assumed that a filter close to the desired characteristics can be designed, the number of taps of the designed filter is too large, and its coefficient values ​​are very complex and random values

So the problem is that to achieve this number of taps and coefficient values, a large-scale circuit structure (adder, multiplier) is required

In addition, when the designed FIR filter is actually used, the amount of calculation is very large, resulting in the problem of overloading the processing load

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