Modulation device and demodulation device
First Claim
Patent Images
1. A modulation device comprising:
- a first spread code generation unit configured to generate a first spread code having a predetermined cycle;
an audio signal input unit to which an audio signal is input;
a low-pass filter configured to cut off a high band component of the input audio signal equal to or higher than a cutoff frequency;
a first modulation unit configured to phase-modulate the first spread code in each cycle on the basis of data code; and
a combining unit configured to combine the audio signal, with the high band component cut off, with a modulation signal that has been generated on the basis of the phase-modulated first spread code and distributed in a frequency range higher than cutoff frequency to output a combined signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A modulation device includes: a spread code generation unit which generates a spread code having a predetermined cycle; an audio signal input unit to which an audio signal is input; a first modulation unit which phase-modulates the spread code in each cycle on the basis of a data code; and a combining unit which combines the audio signal with a modulation signal which has been generated on the basis of the phase-modulated spread code and distributed in a frequency range higher than a predetermined frequency to output a combined signal.
51 Citations
20 Claims
-
1. A modulation device comprising:
-
a first spread code generation unit configured to generate a first spread code having a predetermined cycle; an audio signal input unit to which an audio signal is input; a low-pass filter configured to cut off a high band component of the input audio signal equal to or higher than a cutoff frequency; a first modulation unit configured to phase-modulate the first spread code in each cycle on the basis of data code; and a combining unit configured to combine the audio signal, with the high band component cut off, with a modulation signal that has been generated on the basis of the phase-modulated first spread code and distributed in a frequency range higher than cutoff frequency to output a combined signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A modulation device comprising:
-
a first spread code generation unit configured to generate a first spread code having a predetermined cycle; an audio signal input unit to which an audio signal is input; a first modulation unit configured to phase-modulate the first spread code in each cycle on the basis of data code; and a combining unit configured to combine the audio signal with a modulation signal that has been generated on the basis of the phase-modulated first spread code and distributed in a frequency range higher than a predetermined frequency to output a combined signal; a second spread code generation unit configured to generate a second spread code, which is synchronized with the first spread code and has a code sequence different from the first spread code; a level detection unit configured to detect the volume level of the audio signal input to the audio signal input unit; a second modulation unit configured to phase-modulate and output the second spread code in each cycle on the basis of the data code when the volume level of the audio signal is equal to or lower than a predetermined threshold value and configured to output the second spread code as is when the volume level of the audio signal is equal to or higher than the predetermined threshold value; and a high-pass filter configured to cut off a frequency component equal to or lower than a cutoff frequency of a combined spread code obtained by combining the first spread code output from the first modulation unit and the second spread code output from the second modulation unit, wherein the high-pass filter is configured to set the cutoff frequency to a first value when the volume level of the audio signal is equal to or lower than the predetermined threshold value, and set the cutoff frequency to a second value higher than the first value when the volume level of the audio signal is equal to or higher than the predetermined threshold value, wherein the combining unit combines the audio signal with the combined spread code with the frequency component equal to or lower than the cutoff frequency being cut as the modulation component.
-
-
10. A demodulation device comprising:
-
an audio signal input unit to which a combined signal is input, the combined signal being a combination of an audio signal with a modulation signal, wherein the audio signal has no frequency component higher than a predetermined frequency and the modulation signal has been generated on the basis of a first spread code having a cycle phase-modulated in each cycle on the basis of a data code and has been distributed in a frequency range higher than the predetermined frequency; a high-pass filter configured to cut off a frequency component equal to or lower than a cutoff frequency of the combined signal to extract a component of the modulation signal; and a code determination unit configured to decode the data code combined in the audio signal on the basis of an analysis result of the extracted component of the modulation signal. - View Dependent Claims (11, 12, 13)
-
-
14. A demodulation device comprising:
-
a combined signal input unit to which an audio signal is input, the combined signal being a combination of an audio signal and a modulation signal, which has been generated on the basis of a first spread code having a cycle phase-modulated in each cycle on the basis of a data code and has been distributed in a frequency range higher than a predetermined frequency; a high-pass filter configured to cut off a frequency component equal to or lower than a cutoff frequency of the combined signal to extract a component of the modulation signal; and a code determination unit configured to decode the data code combined in the audio signal on the basis of an analysis result of the extracted component of the modulation signal, wherein the phase-modulated first spread code and a second spread code, which is synchronized with the first spread code and has a code sequence different from the first spread code, are combined in the modulation signal, wherein the demodulation device further comprises; a first correlation detection unit configured to detect a first correlation value, which is a correlation value of the modulation signal with respect to the first spread code before phase modulation; a second correlation detection unit configured to detect a second correlation value, which is a correlation value of the modulation signal with respect to the second spread code; an addition unit configured to add the first correlation value and the second correlation value to output a combined correlation value; and a peak value detection unit configured to detect a peak value of the combined correlation value in each cycle of the first spread code, and wherein the code determination unit decodes the data code on the basis of the magnitude of the peak value of the combined correlation value detected by the peak value detection unit.
-
-
15. A demodulation device comprising:
-
an audio signal input unit that inputs an audio signal, the audio signal being obtained by combining a plurality of spread codes, which are synchronized with each other and have different code sequences; a mode determination unit configured to determine a mode from a reference mode in which a spread code separated from the input audio signal includes a reference spread code, which is not phase-modulated by a data code, and a parallel mode in which the spread code excludes the reference spread code; a first demodulation unit configured to operate in the parallel mode; and a second demodulation unit configured to operate in the reference mode, wherein the first demodulation unit detects respective correlation values of the audio signal with respect to the plurality of spread codes, and demodulates the data code on the basis of the peak of each of the correlation values, wherein the second demodulation unit includes; a first correlation detection unit configured to detect a first correlation value, which is a correlation value of the audio signal with respect to a spread code phase-modulated by the data code; a second correlation detection unit configured to detect a second correlation value, which is a correlation value of the audio signal with respect to the reference spread code; an addition unit configured to add the first correlation value and the second correlation value to output a combined correlation value; a peak detection unit configured to detect a peak value of the combined correlation value in each cycle of the spread code phase-modulated by the data code; and a code determination unit configured to decode the data code combined in the audio signal on the basis of the magnitude of the peak value detected by the peak value detection unit. - View Dependent Claims (16, 17)
-
-
18. An audio signal reproduction apparatus comprising:
-
a demodulation device comprising; an audio signal input unit to which a combined signal is input, the combined signal being a combination of an audio signal with a modulation signal, wherein the audio signal has no frequency component higher than a predetermined frequency and has been generated on the basis of a first spread code having a cycle phase-modulated in each cycle on the basis of a data code and has been distributed in a frequency range higher than the predetermined frequency; a high-pass filter configured to cut off a frequency component equal to or lower than a cutoff frequency of the combined signal to extract a component of the modulation signal; and a code determination unit configured to decode the data code combined in the audio signal on the basis of an analysis result of the extracted component of the modulation signal; a low-pass filter configured to cut off a frequency component equal to or higher than a predetermined frequency of the combined signal and extracts the audio signal; and a high-frequency band extension unit configured to complement a signal component equal to or higher than the predetermined frequency to the extracted audio signal. - View Dependent Claims (19)
-
-
20. An audio signal reproduction apparatus comprising:
-
a demodulation device comprising; an audio signal input unit that inputs an audio signal, the audio signal being obtained by combining a plurality of spread codes, which are synchronized with each other and have different code sequences; a mode determination unit configured to determine a mode from a reference mode in which a spread code separated from the input audio signal includes a reference spread code, which is not phase-modulated by a data code, and a parallel mode in which the spread code excludes the reference spread code; a first demodulation unit configured to operate in the parallel mode; and a second demodulation unit configured to operate in the reference mode, wherein the first demodulation unit detects respective correlation values of the audio signal with respect to the plurality of spread codes, and demodulates the data code on the basis of the peak of each of the correlation values, and wherein the second demodulation unit includes; a first correlation detection unit configured to detect a first correlation value, which is a correlation value of the audio signal with respect to a spread code phase-modulated by the data code; a second correlation detection unit configured to detect a second correlation value, which is a correlation value of the audio signal with respect to the reference spread code; an addition unit configured to add the first correlation value and the second correlation value to output a combined correlation value; a peak detection unit configured to detect a peak value of the combined correlation value in each cycle of the spread code phase-modulated by the data code; and a code determination unit configured to decode the data code combined in the audio signal on the basis of the magnitude of the peak value detected by the peak value detection unit; a low-pass filter configured to cut off a frequency component equal to or higher than a predetermined frequency of the combined signal and extracts the audio signal; and a high-frequency band extension unit configured to complement a signal component equal to or higher than the predetermined frequency to the extracted audio signal.
-
Specification