Digital filter designing method, digital filter designing program, digital filter

Abstract

According to a basic unit filter having a predetermined basic numeric string as a filter coefficient, a high-pass unit filter (H15) and a low-pass unit filter (L13) having pass ranges having a common center frequency Fc are created. These are connected in the longitudinal way to design a band pass filter. Characteristic values obtained by combining a few types of unit filters are cancelled by each other. Thus, without pulling out a necessary frequency band and only by the longitudinal connection of the high-pass unit filter (H15) and the low-pass unit filter (L13), it is possible to extract a superimposed portion as a band pass filter pass range.

Description

technical field [0001] The present invention relates to a design method of a digital filter, a program for designing a digital filter, and a digital filter; in particular, it relates to a delay line with a plurality of taps composed of delayers, and adding each tap signal after multiplying it by several times. And output the FIR filter design method. Background technique [0002] In various electronic devices provided in various fields such as communication, surveying, audio / image signal processing, medical treatment, and seismology, some kind of digital signal processing is generally performed inside. Among the most important basic operations in digital signal processing, there is filtering processing to extract only signals in a desired frequency band from an input signal mixed with various signals or noise. Therefore, most electronic devices that perform digital signal processing use digital filters. [0003] Most digital filters use IIR ((Infinite Impulse Response: Inf...

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Problems solved by technology

[0007] However, the above-mentioned conventional filter design method requires skilled technicians to spend time and effort to design, and thus there is a problem that an FIR filter with desired characteristics cannot be easily designed.

[0008] In addition, even if it is assumed that an FIR filter close to the required characteristics can be designed, the number of taps of the designed filter will be quite large, and its coefficient value will become a very complicated random value

Therefore, there is a problem that a large-scale circuit configuration (adder, multiplier) is required to realize the number of taps and coefficient values.

In addition, when the designed FIR filter is actually used, the amount of calculation will become very large, and the processing load will increase.

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