Spread spectrum communication system
First Claim
1. A spread spectrum communication system, comprising:
- inputting means for inputting an on-off keying signal;
first PN code generating means for generating a first PN code;
spread spectrum modulating means, responsive to said on-off keying signal, for producing a spread spectrum signal in which a carrier signal is modulated by said on-off keying signal and said first PN code;
means for transmitting said spread spectrum signal;
receiving means for receiving said spread spectrum signal transmitted from said transmitting means;
reproducing means for reproducing, based on said spread spectrum signal received by said receiving means, said carrier signal having been modulated by said spread spectrum modulating means, said reproducing means including second PN code generating means for generating a second PN code having a phase which is gradually changed with respect to a phase of said first PN code, and spread spectrum demodulating means for spread spectrum demodulating a received spread spectrum signal by said second PN code from said second PN code generating means; and
means for detecting a reproduced carrier signal and for outputting said on-off keying signal.
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Abstract
A spread spectrum communictdion system includes a transmitter and a receiver, and an on-off keying signal is inputted to the transmitter. A carrier signal is modulated by the on-off keying signal, and a spread spectrum signal is produced by multiplying a modulated signal by a first PN code which is repetition of 3-bit data. The spread spectrum signal is transmitted through a transmission antenna. In the receiver, a second PN code which is repetition of 4-bit data larger than the first PN code by 1 bit is generated. Therefore, a phase of the second PN code becomes coincident with a phase of the first PN code every 12 bits. Then, a spread spectrum demodulation is performed by multiplying a received spread spectrum signal by the second PN code to reproduce the carrier signal being modulated by the on-off keying signal. The on-off keying signal is restored by envelope-detecting a reproduced carrier signal.
51 Citations
17 Claims
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1. A spread spectrum communication system, comprising:
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inputting means for inputting an on-off keying signal; first PN code generating means for generating a first PN code; spread spectrum modulating means, responsive to said on-off keying signal, for producing a spread spectrum signal in which a carrier signal is modulated by said on-off keying signal and said first PN code; means for transmitting said spread spectrum signal; receiving means for receiving said spread spectrum signal transmitted from said transmitting means; reproducing means for reproducing, based on said spread spectrum signal received by said receiving means, said carrier signal having been modulated by said spread spectrum modulating means, said reproducing means including second PN code generating means for generating a second PN code having a phase which is gradually changed with respect to a phase of said first PN code, and spread spectrum demodulating means for spread spectrum demodulating a received spread spectrum signal by said second PN code from said second PN code generating means; and means for detecting a reproduced carrier signal and for outputting said on-off keying signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A remote control system, comprising:
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a key; converting means for converting a key signal from said key into an on-off keying signal; first PN code generating means for generating a first PN code; spread spectrum modulating means, responsive to said on-off keying signal, for producing a spread spectrum signal in which a carrier signal is modulated by said on-off keying signal and said first PN code; means for transmitting said spread spectrum signal; receiving means for receiving said spread spectrum signal as transmitted from said transmitting means; reproducing means, based on said spread spectrum signal received by said receiving means, for reproducing a carrier signal demodulated by said spread spectrum modulating means, said reproducing means including second PN code generating means for generating a second PN code having a phase which is gradually changed with respect to a phase of said first PN code, and spread spectrum demodulating means for spread spectrum demodulating a received spread spectrum signal by said second PN code from said second PN code generating means; and means for detecting a reproduced carrier signal and for outputting said on-off keying signal.
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15. A remote sensing system, comprising:
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a sensor for inputting an on-off keying signal; first PN code generating means for generating a first PN code; spread spectrum modulating means, responsive to said on-off keying signal, for producing a spread spectrum signal in which a carrier signal is modulated by said on-off keying signal and said first PN code; means for transmitting said spread spectrum signal; receiving means for receiving said spread spectrum signal as transmitted from said transmitting means; reproducing means, based on said spread spectrum signal received by said receiving means, for reproducing a carrier signal demodulated by said spread spectrum modulating means, said reproducing means including second PN code generating means for generating a second PN code having a phase which is gradually changed with respect to a phase of said first PN code, and spread spectrum demodulating means for spread spectrum demodulating a received spread spectrum signal by said second PN code from said second PN code generating means; and means for detecting a reproduced carrier signal and for outputting said on-off keying signal.
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16. A spread spectrum communication system, comprising:
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inputting means for inputting an on-off keying signal; first PN code generating means for generating a first PN code; spread spectrum modulating means, responsive to said on-off keying signal and said first PN code, for producing a spread spectrum signal in which a carrier signal is modulated by said on-off keying signal and said first PN code, said spread spectrum modulating means including an oscillator which is enabled or disabled by said on-off keying signal and has a variable capacitance element, and a change of the capacitance of said variable capacitance element being defined by said first PN code; means for transmitting said spread spectrum signal; receiving means for receiving said spread spectrum signal transmitted from said transmitting means; reproducing means for reproducing, based on said spread spectrum signal received by said receiving means, said carrier signal having been modulated by said spread spectrum modulating means; and means for detecting a reproduced carrier signal and for outputting said on-off keying signal.
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17. A spread spectrum communication system, comprising:
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inputting means for inputting an on-off keying signal; first PN code generating means for generating a first PN spread spectrum modulating means, responsive to said on-off keying signal and said first PN code, for producing a spread spectrum signal in which a carrier signal is modulated by said on-off keying signal and said first PN code; means for transmitting said spread spectrum signal; receiving means for receiving said spread spectrum signal transmitted from said transmitting means; reproducing means for reproducing, based on said spread spectrum signal received by said receiving means, said carrier signal having been modulated by said spread spectrum modulating means, said reproducing means including an oscillator for generating said carrier signal, and said oscillator being operated in response to the presence of a spread spectrum signal received by said receiving means; and means for detecting a reproduced carrier signal and for outputting said on-off keying signal.
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Specification