Spread spectrum communication system
First Claim
1. A communication system using intelligence and synchronization signals, each signal being in the form of a repetitive pattern that has a certain duration and that is defined by a certain code to include a plurality of components at different frequencies, a transmitter including a plurality of sequence generator means each operable with one of said codes for developing each of said intelligence and synchronization signals, carrier signal means for developing a plurality of carrier signals at different carrier frequencies, plurality of mixer means each being responsive to one of said carrier signals and to said intelligence and synchronization signals to develop signal components in frequency range that is high in relation to said different frequencies of said components, and signal transmitting means for transmitting signals developed by said plurality of mixer means in a plurality of frequency ranges respectively corresponding to said different carrier frequencies, and a receiver for receiving signals transmitted from said transmitter, a plurality of filter means responsive to received signals to develop output signals in said plurality of frequency ranges, a plurality of detector means responsive to said output signals from said filter means to develop signals corresponding to those applied to said plurality of mixer means of said transmitter means, a plurality of product detector means responsive to output signals from said plurality of mixer means, a plurality of sequence generator means coupled to said plurality of product detector means and operable with codes corresponding to those of said sequence generator means of said transmitter to effect reproduction of said synchronization and intelligence signals by said plurality of product detector means, and means responsive to said synchronization signals for operating said sequence generator means of said receiver in synchronization with said sequence generator means of said transmitter.
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Accused Products
Abstract
In one embodiment of a spread spectrum communication system, an unmodulated synchronization wavetrain and one or more modulated intelligence wavetrains are generated in timed relation and are concurrently propagated but separately detected in a receiver. In another embodiment, wavetrains are modulated by opposite phases of an intelligence signal and so detected in a receiver as to produce a synchronization control signal and an intelligence signal by summing and comparing two received signals. Under microprocessor control, the phase of operation of the sequence generators of the receiver is adjusted to obtain phase and frequency information for effecting phase control for synchronization and also to controllably swallow cycles and accurately adjust the effective frequency of the clock signal. Each sequence generator includes a memory which stores data to control one counter and to define the durations and order of variations of a sequence, the memory being indexed by a second counter at the end of each sequence. The wavetrains may be transmitted on at least one carrier and preferably on a plurality of carriers of different frequencies to transmit energy in a generally uniformly distributed or otherwise desirable manner in a higher frequency range which may be as wide or as narrow a range as may be advantageous.
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Citations
14 Claims
- 1. A communication system using intelligence and synchronization signals, each signal being in the form of a repetitive pattern that has a certain duration and that is defined by a certain code to include a plurality of components at different frequencies, a transmitter including a plurality of sequence generator means each operable with one of said codes for developing each of said intelligence and synchronization signals, carrier signal means for developing a plurality of carrier signals at different carrier frequencies, plurality of mixer means each being responsive to one of said carrier signals and to said intelligence and synchronization signals to develop signal components in frequency range that is high in relation to said different frequencies of said components, and signal transmitting means for transmitting signals developed by said plurality of mixer means in a plurality of frequency ranges respectively corresponding to said different carrier frequencies, and a receiver for receiving signals transmitted from said transmitter, a plurality of filter means responsive to received signals to develop output signals in said plurality of frequency ranges, a plurality of detector means responsive to said output signals from said filter means to develop signals corresponding to those applied to said plurality of mixer means of said transmitter means, a plurality of product detector means responsive to output signals from said plurality of mixer means, a plurality of sequence generator means coupled to said plurality of product detector means and operable with codes corresponding to those of said sequence generator means of said transmitter to effect reproduction of said synchronization and intelligence signals by said plurality of product detector means, and means responsive to said synchronization signals for operating said sequence generator means of said receiver in synchronization with said sequence generator means of said transmitter.
- 9. A communication system including a transmitter and a receiver for transmitting and receiving signals in a frequency range in which certain center frequencies with fixed frequency differences therebetween are assigned to licensed stations operating in said frequency range, said transmitter comprising means for developing a spread spectrum signal that produces minimal interference with transmission and reception of energy through modulation of carrier signals at said center frequencies that are assigned to licensed stations, said spread spectrum signal having primary energy components developed at predetermined fixed primary frequencies that are distributed across at least a substantial portion of said frequency range, each of said predetermined fixed primary frequencies being approximately midway between two of said certain center frequencies, and said receiver comprising means for minimizing response to signals developed through modulation of carrier signals at said center frequencies while developing an integrated response to energy developed at said predetermined fixed frequencies.
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12. A communication system comprising means for transmitting and receiving a plurality of intelligence signals using a plurality of different frequency ranges, each intelligence signal being in the form of a repetitive pattern that has a certain duration and that is defined by a certain intelligence signal code, means utilizing each of said different frequency ranges for transmitting and receiving a complete synchronizing signal that is in the form of a repetitive pattern that has a certain duration and that is defined by a certain synchronizing signal code, said intelligence signals being transmitted in synchronized relation to one another and in timed synchronized relation to said synchronization signal, and synchronizing means responsive to summing of receptions of said synchronizing signal in all of said frequency ranges for effecting the reception of all of said intelligence signals in timed synchronized relation to said synchronizing signal, said certain synchronizing code being distinctively different from said certain intelligence signal code of each of said intelligence signals, and said certain synchronizing code being used in transmitting and receiving said synchronizing signal in each and every one of said frequency ranges to facilitate reliable receiving of said synchronizing signal and to thereby facilitate reliable reception of each of said intelligence signals.
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14. A method of communication through transmitting and receiving of signals in a frequency range in which certain center frequencies with fixed frequency differences therebetween are assigned to licensed stations operating in said frequency range, said transmitting of said signals being performed through developing of a spread spectrum signal that produces minimal interference with transmission and reception of energy at said center frequencies that are assigned to licensed stations, said spread spectrum signal having primary energy components developed at predetermined fixed primary frequencies that are distributed across at least a substantial portion of said frequency range, each of said predetermined fixed primary frequencies being approximately midway between two of said certain center frequencies, and said receiving of said signals being performed with minimal response to signals developed at said center frequencies while developing an integrated response to energy developed at said predetermined fixed frequencies.
Specification