Spectrum spread communication system
First Claim
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1. A transmitter for spectrum spread communication system comprising:
- a PN code generator for generating a PN code;
a frequency synthesizer for changing over and outputting a plurality of different frequency signals in response to said PN code supplied from said PN code generator;
a mixing means for carrying out multiplication between a base band data input signal and said PN code supplied from said PN code generator;
means for modulating a signal supplied form an AC signal source using a signal supplied from said mixing means to convert it into a high frequency signal; and
means for subjecting an output signal of said modulating means to frequency hopping by means of an output signal of said frequency synthesizer;
wherein one cycle of said frequency hopping includes one frequency which is subject to hopping at an interval equal to one cycle of a direct spread signal generated from said modulating means and at least two frequencies one of which is subject to hopping at an interval equal to one cycle of the direct spread signal generated from said modulating means.
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Abstract
A spectrum spread communication system capable of ensuring positive synchronization and improving error rate characteristics of data. At least one frequency is subject to hopping at an interval equal to one cycle of a DS signal during one cycle of frequency hopping and a cycle of changing-over of hopping is controlled depending upon an output signal of a correlation device, resulting in accomplishing synchronization.
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Citations
5 Claims
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1. A transmitter for spectrum spread communication system comprising:
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a PN code generator for generating a PN code; a frequency synthesizer for changing over and outputting a plurality of different frequency signals in response to said PN code supplied from said PN code generator; a mixing means for carrying out multiplication between a base band data input signal and said PN code supplied from said PN code generator; means for modulating a signal supplied form an AC signal source using a signal supplied from said mixing means to convert it into a high frequency signal; and means for subjecting an output signal of said modulating means to frequency hopping by means of an output signal of said frequency synthesizer; wherein one cycle of said frequency hopping includes one frequency which is subject to hopping at an interval equal to one cycle of a direct spread signal generated from said modulating means and at least two frequencies one of which is subject to hopping at an interval equal to one cycle of the direct spread signal generated from said modulating means. - View Dependent Claims (2, 3, 4)
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5. A receiver for spectrum spread communication system comprising:
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a PN code generator for generating a PN code; a frequency synthesizer for changing over and outputting a plurality of different frequency signals in response to said PN code supplied from said PN code generator; a mixer for carrying out multiplication between a signal received by a receiver and a signal supplied from said frequency synthesizer to generate its output signal, said signal received by said receiver being a timer series serial signal including one frequency subject to hopping at an interval equal to one unit of a base band data and at least two frequencies one of which is subject to hopping at an interval equal to one unit of the base band data; a correlation device for carrying out correlation between an output signal of said mixer and said PN code to generate correlation signal; a demodulator for demodulating a signal input thereto to generate a base band output signal; and means for controlling a frequency of said PN code generator in response to said correlation signal.
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Specification