1983 年 39 巻 4 号 p. 230-238
Digital filters have been applied to variable attenuation equalizers for tone-controlling of digitally-recorded music sources. This paper describes an implementation of a digital equalizer with low sensitivity coefficients. This equalizer uses versatile and simplified circuits for high quality signal processing. Several problems are examined from view points of the coefficient quantization effect and finite word length operation, which are inevitable in practical equalizers. Presented here is a new equalizer design procedure which incorporates the coefficient quantization algorithm for decreasing errors caused by finite-length words with small multiplication number. Actual models are also described and compared to conventional procedures. Two useful methods are proposed;one is for estimating the appropriate coefficient word length for the correct frequency response, the other is for estimating the operation length for maintaining high signal quality. Some examples of the estimation are also shown. It is found that the methods can be applied to general equalizer design. Computer simulations verify the usefulness of the methods and the feasibility of the equalizer implementation.