Digital filter designing method, digital filter designing program, digital filter
First Claim
Patent Images
1. A digital filter designing method, comprising:
- creating one or more unit filters having a mutually common pass band based on basic unit filters formed by multiplying respective tap signals of a tapped delay line made up of a plurality of delayers several-fold using filter coefficients made up of a predetermined basic numeric string, adding up those multiplication results and outputting the addition result; and
cascade connecting said one or more unit filters to thereby design a digital filter.
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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 bands having a common center frequency Fc are created. These are connected in the cascade 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 cascade 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 band.
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Citations
22 Claims
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1. A digital filter designing method, comprising:
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creating one or more unit filters having a mutually common pass band based on basic unit filters formed by multiplying respective tap signals of a tapped delay line made up of a plurality of delayers several-fold using filter coefficients made up of a predetermined basic numeric string, adding up those multiplication results and outputting the addition result; and
cascade connecting said one or more unit filters to thereby design a digital filter. - View Dependent Claims (2, 3, 4, 5, 7, 9, 11, 13, 15, 19, 21)
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6. A digital filter designing method, comprising:
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creating a unit filter having relatively wide pass band based on basic unit filters formed by multiplying respective tap signals of a tapped delay line made up of a plurality of delayers several-fold using filter coefficients made up of a predetermined basic numeric string, adding up those multiplication results and outputting the addition result;
designing a high-pass filter and a low-pass filter in such a way that their respective pass bands overlap with each other in the pass band of said unit filter; and
cascade connecting said unit filter, said high-pass filter and said low-pass filter to thereby design a band pass filter having a pass band made up of a superimposed portion of the respective pass bands. - View Dependent Claims (8, 10, 12, 14, 16, 20, 22)
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17. A digital filter constructed by cascade connecting one or more unit filters having a common pass band, said unit filters are created based on basic unit filters having a predetermined basic numeric string as filter coefficients.
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18. A digital filter constructed by cascade connecting the unit filter having a relatively wide pass band created based on basic unit filters having a predetermined basic numeric string as filter coefficients, a high-pass filter and a low-pass filter created in such a way that their respective pass bands overlap with each other in the pass band of said unit filter.
Specification