Codec apparatus

A codec apparatus comprising:

• an A-D converter for converting an inputted analog signal to a digital signal at a first sampling frequency and outputting the digital signal;
• detection means for receiving the digital signal and for detecting a frequency bandwidth of the digital signal;
• and
• changing means, to which the digital signal and a control signal from said detection means are inputted, for converting a first clock signal at the first sampling frequency into a second clock signal at a second sampling frequency, selected from a plurality of sampling frequencies, based upon the control signal, and for outputting the digital signal at intervals determined by the second clock signal.

A codec apparatus for converting an analog signal to a digital signal and for decoding the digital signal to an analog signal, comprising:

• conversion means for converting an inputted analog signal to a first digital signal at an over-sampling frequency;
• output means for receiving the first digital signal and for outputting a second digital signal at intervals determined by a clock signal at a second sampling frequency;
• and
• control means for detecting a frequency bandwidth of the analog signal included in the first digital signal, and for converting a first clock signal at the over-sampling frequency into the clock signal at the second sampling frequency such that the second sampling frequency corresponds to the detected frequency bandwidth.

An apparatus for digitizing an analog signal, comprising:

• a first circuit for sampling the analog signal at a first sampling frequency to produce a first digital signal;
• a bandwidth detection circuit for detecting the bandwidth of the analog signal, said bandwidth detection circuit including,
• a frequency bandwidth extractor for extracting at least first and second frequency bandwidths from the first digital signal, the first frequency bandwidth differing from the second frequency bandwidth,
• a first power determining circuit for comparing the power in the first frequency bandwidth to the power in the second frequency bandwidth, and
• a second power determining circuit for comparing the power in the second frequency bandwidth to the power in the whole bandwidth of the first digital signal;
• a clock circuit for converting a first clock signal at the first sampling frequency to a second clock signal at a second sampling frequency based upon the comparisons of said first and second power determining circuits;
• and
• a second circuit for producing a second digital signal derived from the first digital signal output at intervals determined by the second clock signal.

An apparatus for digitizing an analog signal, comprising:

• a first circuit for sampling the analog signal at a first sampling frequency to produce a first digital signal;
• a bandwidth detection circuit for detecting the bandwidth of the analog signal;
• a clock circuit, responsive to the bandwidth of the analog signal detected by said bandwidth detection circuit, for converting a first clock signal at the first sampling frequency to a second clock signal at a second sampling frequency, the second sampling frequency being selected from a plurality of sampling frequencies;
• and
• a switch, responsive to the second clock signal, for receiving the first digital signal and for outputting the first digital signal at intervals determined by the second clock signal.

An apparatus for digitizing an analog signal, comprising:

• a first circuit for sampling the analog signal at a first sampling frequency to produce a first digital signal;
• a bandwidth detection circuit for detecting the bandwidth of the analog signal;
• a clock circuit, responsive to the bandwidth of the analog signal detected by said bandwidth detection circuit, for producing a clock signal corresponding to a second sampling frequency, the second sampling frequency being selected from a plurality of sampling frequencies;
• a switch, responsive to the clock signal, for receiving the first digital signal and for outputting the first digital signal at intervals determined by the clock signal, wherein the first sampling frequency has a first half-period and a second half-period, the first half-period being equal to the second half-period, and further wherein the clock signal at the second sampling frequency includes a first pulse of equal duration as the first half-period of the first sampling frequency.