Signal processing apparatus, signal processing method, and computer program

A signal processing apparatus comprising:

• an A/D converter configured to output a first digital signal having a predetermined sampling frequency and a quantization bit number a, the A/D converter including a first delta sigma modulator that performs a first delta sigma modulation process on an input analog signal;
• a filter unit configured to pass the first digital signal through a digital filter provided with a predetermined filter characteristic and output a second digital signal having a sampling frequency and a quantization bit number b;
• a second delta sigma modulator configured to perform a second delta sigma modulation process on the second digital signal and output a third digital signal having the predetermined sampling frequency and the quantization bit number a;
• a first bit expander configured to expand the quantization bit number of the third digital signal from a to c to generate a fourth digital signal;
• and
• a first addition unit configured to add the fourth digital signal and an input digital signal having the sampling frequency and a quantization bit number c.

A signal processing apparatus comprising:

• a first delta sigma modulation unit configured to perform a first delta sigma modulation process on an input analog signal to:
• generate a first digital signal having a predetermined sampling frequency and a quantization bit number,
• expand the quantization bit number of the first digital signal from a to c, and
• output a second digital signal;
• a first equalizer unit configured to perform a first equalizing process on an input digital signal having the predetermined sampling frequency and the quantization bit number a with a first target characteristic to:
• generate a first equalized signal,
• perform a delta sigma modulation process on the first equalized signal,
• generate a third digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the third digital signal from a to c, and
• output a fourth digital signal;
• a second equalizer unit configured to perform a second equalizing process on the input digital signal with a second target characteristic to:
• generate a second equalized signal,
• perform a delta sigma modulation process on the second equalized signal,
• generate a fifth digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the fifth digital signal from a to c, and
• output a sixth digital signal;
• a delay unit configured to provide the input digital signal with a delay equivalent to processing delay in the first equalizer unit or the second equalizer unit to:
• generate a seventh digital signal;
• expand the quantization bit number of the seventh digital signal from a to c, and
• output an eighth digital signal;
• a first addition unit configured to add the second digital signal and the fourth digital to generate a ninth digital signal;
• a filter unit configured to pass the ninth digital signal through a digital filter provided with a predetermined filter characteristic and output a tenth digital signal having the predetermined sampling frequency and a quantization bit number b;
• a second delta sigma modulation unit configured to perform a delta sigma modulation process on the tenth digital signal to:
• generate an eleventh digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the eleventh digital signal from a to c, and
• output a twelfth digital signal;
• and
• a second addition unit configured to add the sixth digital signal, the eighth digital signal, and the twelfth digital signal.

A signal processing method comprising:

• outputting a first digital signal having a predetermined sampling frequency and a quantization bit number a by performing a first delta sigma modulation process on an input analog signal;
• passing the first digital signal having the predetermined sampling frequency and the quantization bit number a through a digital filter provided with a predetermined filter characteristic and outputting a second digital signal having the sampling frequency and a quantization bit number b;
• outputting a third digital signal having the predetermined sampling frequency and the quantization bit number a by performing a second delta sigma modulation process on the second digital signal having the quantization bit number b;
• and
• adding the third digital signal and an input digital signal having the sampling frequency and the quantization bit number a.

A signal processing method comprising:

• outputting a first digital signal having a predetermined sampling frequency and a quantization bit number a by performing a first delta sigma modulation process on an input analog signal;
• passing the first digital signal having the predetermined sampling frequency and the quantization bit number a through a digital filter provided with a predetermined filter characteristic and outputting a second digital signal having the predetermining sampling frequency and a quantization bit number b;
• outputting a third digital signal having the predetermined sampling frequency and the quantization bit number a by performing a second delta sigma modulation process on an output of the digital signal having the sampling frequency and the quantization bit number b;
• expanding the quantization bit number of the third digital signal from a to c for an output of the second delta sigma modulation process to generate a fourth digital signal;
• and
• adding the fourth digital signal having an expanded quantization bit number c and an input digital signal having the sampling frequency and a quantization bit number c.

A non-transitory computer-readable storage medium storing a computer program that causes a computer to execute:

• outputting a first digital signal having a predetermined sampling frequency and a quantization bit number a by performing a first delta sigma modulation process on an input analog signal;
• passing the first digital signal having the predetermined sampling frequency and the quantization bit number a through a digital filter provided with a predetermined filter characteristic and outputting a second digital signal having the sampling frequency and a quantization bit number b;
• outputting a third digital signal having the predetermined sampling frequency and the quantization bit number a by performing a second delta sigma modulation process on the second digital signal having the quantization bit number b;
• and
• adding the third digital signal and an input digital signal having the sampling frequency and the quantization bit number a.

A non-transitory computer-readable storage medium storing a computer program that causes a computer to execute:

• outputting a first digital signal having a predetermined sampling frequency and a quantization bit number a by performing a first delta sigma modulation process on an input analog signal;
• passing the first digital signal having the predetermined sampling frequency and the quantization bit number a through a digital filter provided with a predetermined filter characteristic and outputting a second digital signal having the predetermined sampling frequency and a quantization bit number b;
• outputting a third digital signal having the predetermined sampling frequency and the quantization bit number a by performing a second delta sigma modulation process on an output of the digital signal having the sampling frequency and the quantization bit number b;
• expanding the quantization bit number of the third digital signal from a to c for an output of the second delta sigma modulation process to generate a fourth digital signal;
• and
• adding the fourth digital signal having an expanded quantization bit number c and an input digital signal having the sampling frequency and a quantization bit number c.

A signal processing method comprising:

• performing a first delta sigma modulation unit configured to perform a first delta sigma modulation process on an input analog signal to:
• generate a first digital signal having a predetermined sampling frequency and a quantization bit number,
• expand the quantization bit number of the first digital signal from a to c, and
• output a second digital signal;
• performing a first equalizing process on an input digital signal having the predetermined sampling frequency and the quantization bit number a with a first target characteristic to:
• generate a first equalized signal,
• perform a delta sigma modulation process on the first equalized signal,
• generate a third digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the third digital signal from a to c, and
• output a fourth digital signal;
• performing a second equalizing process on the input digital signal with a second target characteristic to:
• generate a second equalized signal,
• perform a delta sigma modulation process on the second equalized signal,
• generate a fifth digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the fifth digital signal from a to c, and
• output a sixth digital signal;
• providing the input digital signal with a delay equivalent to processing delay to:
• generate a seventh digital signal;
• expand the quantization bit number of the seventh digital signal from a to c, and
• output an eighth digital signal;
• adding the second digital signal and the fourth digital to generate a ninth digital signal;
• passing the ninth digital signal through a digital filter provided with a predetermined filter characteristic and output a tenth digital signal having the predetermined sampling frequency and a quantization bit number b;
• performing a delta sigma modulation process on the tenth digital signal to:
• generate an eleventh digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the eleventh digital signal from a to c, and
• output a twelfth digital signal;
• and
• adding the sixth digital signal, the eighth digital signal, and the twelfth digital signal.

A non-transitory computer-readable storage medium having computer readable instructions stored thereon that, when executed by a computer, cause the computer to perform the steps of:

• performing a first delta sigma modulation unit configured to perform a first delta sigma modulation process on an input analog signal to:
• generate a first digital signal having a predetermined sampling frequency and a quantization bit number,
• expand the quantization bit number of the first digital signal from a to c, and
• output a second digital signal;
• performing a first equalizing process on an input digital signal having the predetermined sampling frequency and the quantization bit number a with a first target characteristic to:
• generate a first equalized signal,
• perform a delta sigma modulation process on the first equalized signal,
• generate a third digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the third digital signal from a to c, and
• output a fourth digital signal;
• performing a second equalizing process on the input digital signal with a second target characteristic to:
• generate a second equalized signal,
• perform a delta sigma modulation process on the second equalized signal,
• generate a fifth digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the fifth digital signal from a to c, and
• output a sixth digital signal;
• providing the input digital signal with a delay equivalent to processing delay to:
• generate a seventh digital signal;
• expand the quantization bit number of the seventh digital signal from a to c, and
• output an eighth digital signal;
• adding the second digital signal and the fourth digital to generate a ninth digital signal;
• passing the ninth digital signal through a digital filter provided with a predetermined filter characteristic and output a tenth digital signal having the predetermined sampling frequency and a quantization bit number b;
• performing a delta sigma modulation process on the tenth digital signal to:
• generate an eleventh digital signal having the predetermined sampling frequency and the quantization bit number a,
• expand the quantization bit number of the eleventh digital signal from a to c, and
• output a twelfth digital signal;
• and
• adding the sixth digital signal, the eighth digital signal, and the twelfth digital signal.