# US 5,706,308 A · Signal processing apparatus and method for sigma-delta modulated signals including gain adjustment

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- Number: US 5,706,308 A
- Document ID: US5706308A
- Status: Granted
- Kind: A
- Application number: 08/753,004
- Filed: 1996-11-19
- Granted: 1998-01-06
- Earliest claimed: 1995-11-29
- Assignees: Sony Corporation
- Inventors: Gen Ichimura
- Web page: https://patentgrep.com/patent/US5706308A

## CPC

- H03G 3/3089: {Control of digital or coded signals}
- H03M 3/488: {using automatic control}
- H04B 14/06: using differential modulation, e.g. delta modulation
- H03G: CONTROL OF AMPLIFICATION
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)
- H04B: TRANSMISSION

## Abstract

A signal processing apparatus in which the effective dynamic range information for maintaining linearity of an output signal is appended to a transmitted 1-bit digital signal as ancillary data. When the 1-bit signal is converted into a multi-bit digital signal, the gain of the 1-bit signal is adjusted on the basis of the effective dynamic range information.

## Claims

### Claim 1

A signal processing apparatus for processing a digital data string formed by a synchronization signal, subdata and sigma-delta modulated main data having a sampling frequency equal to m.times.fs (Hz), where m is a positive integer larger than 1 (m>1) and formed as a 1-bit digital signal, comprising:
data separating means for separating the main data and the subdata from the transmitted digital data string;
data conversion means for converting the 1-bit main data having the sampling frequency equal to m.times.fs (Hz), where m>1, separated by the data separating means, into a quantized k-bit digital signal having a sampling frequency equal to n.times.fs (Hz), where n is a positive integer smaller than m (m>n), and k is a positive integer larger than 1 (k>1); wherein
said data conversion means includes gain adjustment means for maintaining linearity of a converted main data output;
said gain adjustment means being controlled on a basis of effective dynamic information specifying a range of linearity of the main data output contained in the subdata separated by the data separating means.

### Claim 2 (depends on 1)

The signal processing apparatus as claimed in claim 1 wherein the data conversion means further includes an FIR filter and a decimator.

### Claim 3 (depends on 1)

The signal processing apparatus as claimed in claim 1 wherein the subdata separated from the transmitted digital data string further includes emphasis information and sampling frequency information.

### Claim 4

A signal processing method for converting a digital data string formed by a synchronization signal, subdata and sigma-delta modulated main data formed as a 1-bit digital signal and having a sampling frequency equal to m.times.fs (Hz), where m is a positive integer larger than 1 (m>1), into a quantized k-bit digital signal, having a sampling frequency equal to n.times.fs (Hz), where n is a positive integer smaller than m (m>n), and k is a positive integer larger than 1 (k>1), comprising the steps of:
separating the main data and the subdata from the transmitted digital data string;
converting the 1-bit main data with the sampling frequency equal to m.times.fs (Hz), where m>1, separated by the step of separating, into a quantized k bit digital signal having a sampling frequency equal to n.times.fs (Hz), where n is a positive integer smaller than m (m>n) and k is a positive integer larger than 1 (k>1); and
adjusting a gain of the main data output from said step of converting for maintaining linearity of a converted main data output on a basis of effective dynamic information specifying a range of linearity of the main data output contained in the subdata for maintaining linearity of the converted main data output.