Signal processing circuit for spread spectrum communications
First Claim
1. A digital correlator comprising:
- non-inverting-or-inverting amplifier for receiving a signal obtained by a direct sequence type spread spectrum communication, for converting the received signal into a baseband signal and for inverting or not inverting a polarity of the received signal according to a polarity of a spreading code signal;
an analog-to-digital converter for performing an analog-to-digital conversion on an output of the non-inverting-or-inverting amplifier;
an integrator for integrating a digital signal obtained as a result of the analog-to-digital conversion performed by the analog-to-digital converter; and
a squaring device for calculating a square of an output of the integrator and for outputting data representing a correlation according to the calculated square of the output of the integrator.
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Abstract
A digital correlator used in a receiving component of a spread spectrum communication system of a direct sequence modulation type is disclosed. A polarity of an input baseband signal is controlled by being inverted or not inverted according to a polarity of a spreading code signal by an amplifier, and the input baseband signal controlled is converted by an analog-to-digital converter into a digital signal. The digital signal is integrated for a prescribed period in an integrator, and a square of an integrated digital signal is calculated in a squaring device to obtain a squared value indicating a degree of a correlation between the input baseband signal and the spreading code signal. In cases where the input baseband signal and the spreading code signal correlate with each other, the squared value gradually increases with the passage of time. In contrast, in cases where the input baseband signal and the spreading code signal do not correlate with each other, the squared value is maintained to a low value. Therefore, the digital correlator can be manufactured by a simplified configuration.
34 Citations
10 Claims
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1. A digital correlator comprising:
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non-inverting-or-inverting amplifier for receiving a signal obtained by a direct sequence type spread spectrum communication, for converting the received signal into a baseband signal and for inverting or not inverting a polarity of the received signal according to a polarity of a spreading code signal; an analog-to-digital converter for performing an analog-to-digital conversion on an output of the non-inverting-or-inverting amplifier; an integrator for integrating a digital signal obtained as a result of the analog-to-digital conversion performed by the analog-to-digital converter; and a squaring device for calculating a square of an output of the integrator and for outputting data representing a correlation according to the calculated square of the output of the integrator.
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2. A digital correlator comprising:
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an analog-to-digital converter for receiving a signal obtained by a direct sequence type spread spectrum communication, for converting the received signal into a baseband signal and for performing an analog-to-digital conversion on the baseband signal; a signal processing circuit for changing a polarity of a digital signal obtained as a result of the analog-to-digital conversion performed by the analog-to-digital converter according to a polarity of a spreading code signal; an integrator for integrating an output of the signal processing circuit; and a squaring device for calculating a square of an output of the integrator and for outputting data representing a correlation according to the calculated square of the output of the integrator.
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3. A digital correlator comprising:
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a first analog-to-digital converter for receiving an input signal obtained by a direct sequence type spread spectrum communication, for converting the input signal into a first baseband signal and for performing an analog-to-digital conversion for the first baseband signal to obtain a first converted signal; an inverting amplifier having a gain of 1 for receiving the input signal obtained by the direct sequence type spread spectrum communication and for changing a polarity of the input signal; a second analog-to-digital converter for converting the input signal of which the polarity is changed by the inverting amplifier into a second baseband signal and for performing an analog-to-digital conversion for the second baseband signal to obtain a second converted signal; selecting means for selecting the first converted signal obtained by the first analog-to-digital converter or the second converted signal obtained by the second analog-to-digital converter while changing the selection of the first or second converted signal according to a polarity of a spreading code signal and obtaining a correlation signal by serially connecting the first and second converted signals selected; an integrator for integrating the correlation signal obtained by the selecting means to obtain an integrated correlation signal; and
a squaring device for calculating a square of the integrated correlation signal obtained by the integrator and for outputting the square of the integrated correlation signal as a correlation between the input signal and the spreading code signal.
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4. A digital correlator comprising:
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an analog-to-digital converter for receiving a signal obtained by a direct sequence type spread spectrum communication, for converting the received signal into a baseband signal and for performing an analog-to-digital conversion on the baseband signal; a first integrator for integrating an output of the analog-to-digital signal when a polarity of a spreading code signal is positive; a second integrator for integrating the output of the analog-to-digital signal when the polarity of the spreading code signal is negative; an adder for calculating a difference between outputs of the first and second integrators; a squaring device for calculating a square of an output of the adder and for outputting data representing a correlation according to the calculated square of the output of the adder.
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5. A digital correlator comprising:
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an analog-to-digital converter for receiving a signal obtained by a direct sequence type spread spectrum communication, for converting the received signal into a baseband signal and for performing an analog-to-digital conversion on the baseband signal; an integrator for integrating outputs of the analog-to-digital converter by addition or subtracting the outputs of the analog-to-digital converter according to a polarity of a spreading code signal; and a squaring device for calculating a square of an output of the integrator and for outputting data representing a correlation according to the calculated square of the output of the integrator.
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6. A digital correlation detecting circuit comprising:
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in-phase component extracting means for extracting an in-phase component from an input signal; first non-inverting-or-inverting amplifier for converting the in-phase component of the input signal extracted by the in-phase component extracting means into an in-phase baseband signal and for inverting or not inverting a polarity of the in-phase baseband signal according to a polarity of an inphase component of a spreading code signal to obtain an in-phase correlation signal; a first analog-to-digital converter for performing an analog-to-digital conversion for the in-phase correlation signal obtained by the first non-inverting-or-inverting amplifier to obtain a converted in-phase correlation signal; a first integrator for integrating the converted in-phase correlation signal obtained by the first analog-to-digital converter to obtain an integrated in-phase correlation signal; a first square device for calculating a square of the integrated in-phase correlation signal obtained by the first integrator to obtain the square of the integrated in-phase correlation signal as an in-phase correlation between the in-phase component of the input signal and the in-phase component of the spreading code signal; quadrature component extracting means for extracting a quadrature component from the input signal; second non-inverting-or-inverting amplifier for converting the quadrature component of the input signal extracted by the quadrature component extracting means into a quadrature baseband signal and for inverting or not inverting a polarity of the quadrature baseband signal according to a polarity of a quadrature component of the spreading code signal to obtain a quadrature correlation signal; a second analog-to-digital converter for performing an analog-to-digital conversion for the quadrature correlation signal obtained by the second non-inverting-or-inverting amplifier to obtain a converted quadrature correlation signal;
a second integrator for integrating the converted quadrature correlation signal obtained by the second analog-to-digital converter to obtain an integrated quadrature correlation signal;a second square device for calculating a square of the integrated quadrature correlation signal obtained by the second integrator to obtain the square of the integrated quadrature correlation signal as a quadrature correlation between the quadrature component of the input signal and the quadrature component of the spreading code signal; and
an adder for adding the in-phase correlation obtained by the first square device and the quadrature correlation obtained by the second square device to obtain a correlation between the input signal and the spreading code signal.
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7. A digital correlation detecting circuit comprising:
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in-phase component extracting means for extracting an in-phase component from an input signal; a first analog-to-digital converter for converting the in-phase component of the input signal into an in-phase component of an in-phase baseband signal and for performing an analog-to-digital conversion for the in-phase baseband signal to obtain a converted in-phase baseband signal; a first signal processing circuit for changing a polarity of the converted in-phase baseband signal obtained by the first analog-to-digital converter according to a polarity of an in-phase component of a spreading code signal to obtain an in-phase correlation signal; a first integrator for integrating the in-phase correlation signal obtained by the first signal processing circuit to obtain an integrated in-phase correlation signal; and
a first square device for calculating a square of the integrated in-phase correlation signal obtained by the first integrator to obtain the square of the integrated in-phase correlation signal as an in-phase correlation between the inphase component of the input signal and the in-phase component of the spreading code signal;quadrature component extracting means for extracting a quadrature component from the input signal; a second analog-to-digital converter for converting the quadrature component of the input signal into a quadrature component of a quadrature baseband signal and for performing an analog-to-digital conversion for the quadrature baseband signal to obtain a converted quadrature baseband signal; a second signal processing circuit for changing a polarity of the converted quadrature baseband signal obtained by the second analog-to-digital converter according to a polarity of an quadrature component of the spreading code signal to obtain a quadrature correlation signal; a second integrator for integrating the quadrature correlation signal obtained by the second signal processing circuit to obtain an integrated quadrature correlation signal; and a second square device for calculating a square of the integrated quadrature correlation signal obtained by the second integrator to obtain the square of the integrated quadrature correlation signal as a quadrature correlation between the quadrature component of the input signal and the quadrature component of the spreading code signal; and an adder for adding the in-phase correlation obtained by the first square device and the quadrature correlation obtained by the second square device to obtain a correlation between the input signal and the spreading code signal.
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8. A digital correlation detecting circuit comprising:
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in-phase component extracting means for extracting an in-phase component from an input signal; a first analog-to-digital converter for receiving the in-phase component of the input signal obtained by the in-phase component extracting means, for converting the in-phase component of the input signal into a first in-phase baseband signal and for performing an analog-to-digital conversion for the first in-phase baseband signal to obtain a first converted in-phase baseband signal; an in-phase inverting amplifier having a gain of 1 for receiving the in-phase component of the input signal obtained by the in-phase component extracting means and for changing a polarity of the in-phase component of the input signal;
a second analog-to-digital converter for converting the inphase component of the input signal of which the polarity is changed by the in-phase inverting amplifier into a second inphase baseband signal and for performing an analog-to-digital conversion for the second in-phase baseband signal to obtain a second converted in-phase baseband signal;in-phase selecting means for selecting the first converted in-phase baseband signal obtained by the first analog-to-digital converter or the second converted in-phase baseband signal obtained by the second analog-to-digital converter while changing the selection of the first or second converted in-phase baseband signal according to a polarity of an inphase component of a spreading code signal and obtaining an in-phase correlation signal by serially connecting the first and second converted in-phase baseband signals selected;
an in-phase integrator for integrating the in-phase correlation signal obtained by the in-phase selecting means to obtain an integrated in-phase correlation signal;an in-phase squaring device for calculating a square of the integrated in-phase correlation signal obtained by the inphase integrator and for outputting the square of the integrated in-phase correlation signal as an in-phase correlation between the in-phase component of the input signal and the in-phase component of the spreading code signal; quadrature component extracting means for extracting an quadrature component from the input signal; a third analog-to-digital converter for receiving the quadrature component of the input signal obtained by the quadrature component extracting means, for converting the quadrature component of the input signal into a first quadrature baseband signal and for performing an analog-to-digital conversion for the first quadrature baseband signal to obtain a first converted quadrature baseband signal; a quadrature inverting amplifier having a gain of 1 for receiving the quadrature component of the input signal obtained by the quadrature component extracting means and for changing a polarity of the quadrature component of the input signal; a fourth analog-to-digital converter for converting the quadrature component of the input signal of which the polarity is changed by the quadrature inverting amplifier into a second quadrature baseband signal and for performing an analog-to-digital conversion for the second quadrature baseband signal to obtain a second converted quadrature baseband signal;
quadrature selecting means for selecting the first converted quadrature baseband signal obtained by the third analog-to-digital converter or the second converted quadrature baseband signal obtained by the fourth analog-to-digital converter while changing the selection of the first or second converted quadrature baseband signal according to a polarity of a quadrature component of the spreading code signal and obtaining a quadrature correlation signal by serially connecting the first and second converted quadrature baseband signals selected;a quadrature integrator for integrating the quadrature correlation signal obtained by the quadrature selecting means to obtain an integrated quadrature correlation signal; a quadrature squaring device for calculating a square of the integrated quadrature correlation signal obtained by the quadrature integrator and for outputting the square of the integrated quadrature correlation signal as a quadrature correlation between the quadrature component of the input signal and the quadrature component of the spreading code signal; and an adder for adding the in-phase correlation obtained by the in-phase squaring device and the quadrature correlation obtained by the quadrature squaring device to obtain a correlation between the input signal and the spreading code signal.
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9. A digital correlation detecting circuit comprising:
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in-phase component extracting means for extracting an in-phase component from an input signal; a first analog-to-digital converter for converting the in-phase component of the input signal into an in-Phase baseband signal and for performing an analog-to-digital conversion for the in-phase baseband signal to obtain a converted in-phase baseband signal; a first integrator for integrating the converted in-phase baseband signal obtained by the first analog-to-digital converter in cases where a polarity of an in-phase component of a spreading code signal is positive and obtaining a first in-phase correlation signal; a second integrator for integrating the converted in-phase baseband signal obtained by the first analog-to-digital converter in cases where the polarity of the in-phase component of the spreading code signal is negative and obtaining a second in-phase correlation signal; an in-phase adder for calculating an in-phase difference between the first in-phase correlation signal obtained by the first integrator and the second in-phase correlation signal obtained by the second integrator; an in-phase squaring device for calculating a square of the in-phase difference calculated by the in-phase adder to obtain the square of the in-phase difference as an in-phase correlation between the in-phase component of the input signal and the in-phase component of the spreading code signal;
quadrature component extracting means for extracting a quadrature component from the input signal;a second analog-to-digital converter for converting the quadrature component of the input signal into an quadrature baseband signal and for performing an analog-to-digital conversion for the quadrature baseband signal to obtain a converted quadrature baseband signal;
a third integrator for integrating the converted quadrature baseband signal obtained by the second analog-to-digital converter in cases where a polarity of a quadrature component of the spreading code signal is positive and obtaining a first quadrature correlation signal;a fourth integrator for integrating the converted quadrature baseband signal obtained by the second analog-to-digital converter in cases where the polarity of the quadrature component of the spreading code signal is negative and obtaining a second quadrature correlation signal; an quadrature adder for calculating an quadrature difference between the first quadrature correlation signal obtained by the third integrator and the second quadrature correlation signal obtained by the fourth integrator; an quadrature squaring device for calculating a square of the quadrature difference calculated by the quadrature adder to obtain the square of the quadrature difference as an quadrature correlation between the quadrature component of the input signal and the quadrature component of the spreading code signal; and an adder for adding the in-phase correlation obtained by the in-phase squaring device and the quadrature correlation obtained by the quadrature squaring device to obtain a correlation between the input signal and the spreading code signal.
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10. A digital correlation detecting circuit comprising:
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in-phase component extracting means for extracting an in phase component from an input signal;
a first analog-to-digital converter for converting the inphase component of the input signal into an in-phase baseband signal and for performing an analog-to-digital conversion for the in-phase baseband signal to obtain a converted in-phase baseband signal;a first integrator for integrating the converted in-phase baseband signal obtained by the first analog-to-digital converter while adding the converted in-phase baseband signal in cases where a polarity of an in-phase component of a spreading code signal is positive and subtracting the converted in-phase baseband signal in cases where the polarity of the in-phase component of the spreading code signal is negative and for obtaining an in-phase correlation signal;
a first squaring device for calculating a square of the inphase correlation signal of the first integrator to obtain the square of the in-phase correlation signal as an in-phase correlation between the in-phase component of the input signal and the in-phase component of the spreading code signal;
quadrature component extracting means for extracting an quadrature component from the input signal;
a second analog-to-digital converter for converting the quadrature component of the input signal into an quadrature baseband signal and for performing an analog-to-digital conversion for the quadrature baseband signal to obtain a converted quadrature baseband signal;
a second integrator for integrating the converted quadrature baseband signal obtained by the second analog-to-digital converter while adding the converted quadrature baseband signal in cases where a polarity of an quadrature component of the spreading code signal is positive and subtracting the converted quadrature baseband signal in cases where the polarity of the quadrature component of the spreading code signal is negative and for obtaining an quadrature correlation signal;a second squaring device for calculating a square of the quadrature correlation signal of the second integrator to obtain the square of the quadrature correlation signal as an quadrature correlation between the quadrature component of the input signal and the quadrature component of the spreading code signal; and an adder for adding the in-phase correlation obtained by the first squaring device and the quadrature correlation obtained by the second squaring device to obtain a correlation between the input signal and the spreading code signal.
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Specification