Patent ID: 6166873
Filing Date: 2000-12-26
Classification: G11B,H03M,H04B

Abstract:
An audio signal transmitting apparatus for transmitting a digit audio signal via a transmitting path which is constructed such that a digital signal having a predetermined number of bits per sample is transmitted with a predetermined sampling frequency, comprising:analog-to-digital converting means for converting an input analog signal into an output digital signal having a predetermined number of bits per sample with a first sampling frequency higher than an audio frequency band;filter means connected to the analog-to-digital converting means for reducing the first sampling frequency of the output digital signal output from said analog-to-digital converting means, and then converting the predetermined number of bits per sample digital signal into an m-bits per sample digital signal where where m-bits per sample is greater than the predetermined number of bits per sample and where m is an integer; andnoise shaping means connected directly to the filter means in series for reducing the number of bits of the m-bits per sample of the output digital signal from said filter means from m-bits per sample to n-bits per sample, suppressing the requantization noise in the audio-frequency band by means of shifting the requantization noise in the audio-frequency bank to a higher frequency band, and supplying the digital audio signal to said transmitting path wherein the noise shaping means comprises detecting means for detecting an energy distribution of the digital signal from said filter means, and switches the frequency characteristic of the noise shaping corresponding to the detected result from the detecting means.