3-mode PCM/DPCM/APCM maximizing dynamic range

• US 5,128,963 A
• Filed: 04/29/1987
• Issued: 07/07/1992
• Est. Priority Date: 01/31/1985
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Akagiri, Kenzo
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Smith, Ralph
• Application Number:
  US07/043,853
• Time in Patent Office: 1,896 Days
• Field of Search: 375/25, 375/27, 375/30, 375/31, 375/33, 375/34, 375/122, 358/13, 358/135, 381/29, 381/31, 371/37, 371/1, 332/9 R, 332/110
• US Class Current: 375/244
• CPC Class Codes: H04B 14/046 Systems or methods for reducing noise or bandwidth

Abstract

It has been observed that the S/N ratio of differential-mode PCM and summation-mode PCM with respect to quantization noise is improved at low frequencies and high frequencies, respectively, and consequently the dynamic range thereof is increased. An input signal is divided into blocks of a predetermined number of bits, and, for each block, the one of the general-mode PCM, differential-mode PCM, and summation-mode PCM mode is selected in which adaptive encoding is most efficient, and consequently the quantization noise is smallest, and the input signal data in the mode selected for each block is transmitted together with a mode signal and an adaptive data signal, etc. It has also been observed that the closer to the main signal, the larger the masking effect on the sense of hearing, so that the S/N ratio in terms of the sense of hearing is improved by changing the noise spectrum during digitization to correspond to the spectrum of the input signal.

Claims

1. A method for transmitting digital signals comprising the steps of:

receiving input digital data including a first series of sampled waveform value data;

producing at least one of a second series of difference value data as differential PCM mode digital data and a third series of sum value data as additive PCM mode digital data from said series of sampled waveform value data;

comparing, for each of successive predetermined periods, the maximum value of at least two of said first, second and third series, said maximum value being defined by the sample maximum of said first series, the maximum difference value of said second series, and the maximum addition value of said third series;

selecting the one of said first, second and third data series which provides the least maximum value thereof for each said predetermined period;

producing mode signal data indicating the selected data series; and

transmitting the selected data series together with said mode signal data.

2. Apparatus for transmitting digital signals comprising:

means for receiving input digital data including a first series of sampled waveform value data;

means for producing at least one of a second series of difference value data as differential PCM mode digital data and a third series of sum value data as additive PCM mode digital data from said series of sampled waveform value data;

means for comparing each maximum value of at least two of said first, second and third data series for each of successive predetermined periods, said maximum value being defined by the sample maximum of said first series, the maximum difference value of said second series, and the maximum addition value of said third series;

means for selecting the one of said first, second and third data series which provides the least maximum value thereof for each said predetermined period;

means for producing mode signal data indicating the selected data series; and

means for transmitting the selected data series together with said mode signal data.

3. A method for transmitting digital signals comprising the steps of:

receiving an input signal;

producing a predictive value signal responsive to said input signal;

producing a differential signal from said input signal and said predictive value signal;

providing said differential signal to a spectrum changing circuit means;

obtaining an error component between the input and output of said spectrum changing circuit means; and

feeding back said error component through error predicting means to the input side of said spectrum changing circuit means so as to control the frequency spectrum of the noise of said input signal to independently change the frequency spectrum of the noise with respect to the frequency spectrum of said input signal.

4. Apparatus for transmitting digital signals comprising:

means for receiving an input signal

means for producing a predictive value signal responsive to said input signal;

means for producing a differential signal from said input signal and said predictive value signal;

means for providing said differential signal to a spectrum changing circuit means;

means for obtaining an error component between the input and output of said circuit means; and

means for feeding back said error component through error predicting means to the input side of said spectrum changing circuit means so as to control the frequency spectrum of the noise of said input signal to independently change the frequency spectrum of the noise with respect to the frequency spectrum of said input signal.

5. A method for transmitting digital signals comprising the steps of:

receiving input digital dta including a series of sampled waveform value data;

producing a series of difference value data as differential PCM mode digital data and a series of sum value data as adaptive PCM mode digital data from a plurality of sampled waveform value data adjacent to each other in time in said series of the sampled waveform value data, respectively;

producing a plurality of words of the digital data by adaptive processing either said series of difference value data or sum value data included in every predetermined period;

producing information signal data indicating the adaptive processing taken in every predetermined period; and

transmitting the adaptive processed plurality of words of the digital data together with said information signal data and at least one of said plurality of sampled waveform value data.

6. An apparatus for transmitting digital signals comprising:

means for receiving input digital data including a series of sampled waveform value data;

means for producing a series of difference value data as differential PCM mode digital data and a series of sum value data as additive PCM mode digital data from a plurality of samples adjacent to each other in time in said series of the sampled waveform value data, respectively;

means for producing a plurality of words of the digital data by adaptive processing either said series of difference value data or sum value data included in every predetermined period;

means for producing information signal data indicating the adaptive processing taken in every predetermined period; and

means for transmitting the adaptive processed plurality of words of the digital data together with said information signal data and at least one of said plurality of sampled waveform value data.

7. A method for transmitting digital signals comprising the steps of:

receiving an input signal;

producing a predictive value signal from said input signal;

producing a differential signal between said input signal and said predictive value signal;

providing said differential signal to a circuit means for changing the frequency spectrum of the signal;

obtaining an error component between the input and output of said circuit means; and

feeding back said error component through error predicting means to the input side of said circuit means so as to control the frequency spectrum of the noise of said input signal to independently change the frequency spectrum of the noise with respect to the frequency spectrum of said input signal.

8. An apparatus for transmitting digital signals comprising:

means for receiving an input signal;

means for producing a predictive value signal from said input signal;

means for producing a differential signal between said input signal and said predictive value signal;

means for providing said differential signal to a circuit means for changing the frequency spectrum of the signal;

means connected to said circuit means for obtaining an error component between the input and output of said circuit means; and

means for feeding back said error component through error predicting means to the input side of said circuit means so as to control the frequency spectrum of the noise of said input signal to independently change the frequency spectrum of the noise with respect to the frequency spectrum of said input signal.

9. A method for transmitting digital signals comprising the steps of:

receiving input digital data including a first series of sampled waveform value data;

producing a second series of difference value data as differential PCM mode digital data, and producing a third series of sum value data as adaptive PCM mode digital data, from a plurality of consecutive sampled waveform value data in said series of sampled waveform value data;

producing a plurality of words of digital data by adaptively processing of a single selected one of said first, second or third series, for each of a plurality of consecutive predetermined periods;

producing an information signal data for determining said single selected series taken in each said predetermined period; and

transmitting said plurality of words together with said information signal data and at least one of said plurality of sampled waveform value data.

10. Apparatus for transmitting digital signals comprising:

means for receiving input digital data including a first series of sampled waveform value data;

means for producing a second series of difference value data as differential PCM mode digital data, and producing a third series of sum value data as additive PCM mode digital data, from a plurality of consecutive samples in said first series of sampled waveform value data;

means for producing a plurality of words of digital data by adaptively processing a single selected one of said first, second or third series, for each of a plurality of consecutive predetermined periods;

means for producing information signal data indicating said single selected series in each said predetermined period; and

means for transmitting said plurality of words together with said information signal data and at least one of said plurality of sampled waveform value data.

11. A method for transmitting digital signals comprising the steps of:

receiving input digital data including a series of sampled waveform value data;

producing at least one of a series of difference value data as differential PCM mode digital data and a series of sum value data as additive PCM mode digital data from said series of sampled waveform value data;

detecting the maximum difference value of said differential PCM mode data and the maximum addition value of said additive PCM mode data;

comparing all of said maximum values in every predetermined period;

selecting one of said data series which provides the least of the maximum values thereof among said series of the sampled waveform value data, difference value data and sum value data every said predetermined period;

producing mode signal data indicating said selected one data series; and

transmitting the selected data series together with said mode signal data.

12. An apparatus for transmitting digital signals comprising:

means for receiving input digital data including a series of sampled waveform value data;

means for producing at least one of a series of difference value data as differential PCM mode digital data and a series of sum value data as additive PCM mode digital data from said series of sampled waveform value data;

means detecting the maximum diffference value of said differential PCM mode data and the maximum addition value of said additive PCM mode data and for comparing all said maximum values in every predetermined period;

means for selecting one data series which provides the least of the maximum values thereof among said series of the sampled waveform value data, difference value data and sum value data every said predetermined period;

means for producing mode signal data indicating the selected data series; and

means for transmitting the selected data series together with said mode signal data.