Receiver for a spread spectrum communication system having a time-multiplexed convolver
First Claim
1. A time-multiplexed convolver for convolving an input signal having a predetermined chip rate with a time reversed-time multiplexed reference signal comprising:
- a piezoelectric substrate;
a first interdigital transducer for launching a first surface acoustic wave in said piezoelectric substrate along a first path in response to the input signal;
a second interdigital transducer displaced from said first interdigital transducer for launching a second surface acoustic wave along said first path towards said first interdigital transducer in response to the time reversed-time multiplexed reference signal, said first path between said first and second interdigital transducers defining an interaction region for said first and second surface acoustic waves; and
a first segmented summing bus disposed on said piezoelectric substrate between said first and second interdigital transducers for generating time-multiplexed samples from the convolution of said first and second surface acoustic waves, said first segmented summing bus having a connector bus outside said interaction region and a plurality of equally spaced fingers extending from said connector bus into said interaction region.
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Abstract
A convolver having at least a first interdigital transducer for generating a first surface acoustic wave in response to an input signal and a second interdigital transducer for generating a second surface acoustic wave counter to the first surface acoustic wave in response to a time reversed-time multiplexed reference signal. A segmented summing bus having a plurality of fingers extending into the interaction region of the first and second surface acoustic waves generates a plurality of samples indicative of the convolution of the first and second surface acoustic waves. The convolver also includes a pair of acoustic horns, one disposed between the segmented summing bus and each of the interdigital transducers and a ground bus having a plurality of filler segments extending intermediate the fingers of the segmented summing bus.
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Citations
38 Claims
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1. A time-multiplexed convolver for convolving an input signal having a predetermined chip rate with a time reversed-time multiplexed reference signal comprising:
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a piezoelectric substrate; a first interdigital transducer for launching a first surface acoustic wave in said piezoelectric substrate along a first path in response to the input signal; a second interdigital transducer displaced from said first interdigital transducer for launching a second surface acoustic wave along said first path towards said first interdigital transducer in response to the time reversed-time multiplexed reference signal, said first path between said first and second interdigital transducers defining an interaction region for said first and second surface acoustic waves; and a first segmented summing bus disposed on said piezoelectric substrate between said first and second interdigital transducers for generating time-multiplexed samples from the convolution of said first and second surface acoustic waves, said first segmented summing bus having a connector bus outside said interaction region and a plurality of equally spaced fingers extending from said connector bus into said interaction region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A convolver for convolving an input signal with a time reversed-time multiplexed reference signal comprising:
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a piezoelectric substrate; a first interdigital transducer for launching a first surface acoustic wave along a first path on the surface of said substrate in response to said input signal; a second interdigital transducer for launching a second surface acoustic wave along said first path on the surface of said substrate in response to said time reversed-time multiplexed reference signal, said first path defining an interaction region of said first and second surface acoustic waves; a segmented summing bus disposed intermediate said first and second interdigital transducers, said segmented summing bus having a plurality of equally spaced fingers extending into said interaction region; a ground bus having a plurality of filler segments extending into said interaction region between said equally spaced fingers; and a pair of acoustic horns, one disposed intermediate said segmented summing bus and each of said first and second interdigital transducers. - View Dependent Claims (19, 20)
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21. A spread spectrum receiver for demodulating a M-ary orthogonal keying data modulated signal having a predetermined chipping rate comprising an input amplifier for converting the received M-ary orthogonal keying data modulated signal to an input signal, convolver means for convolving said input signal with time reversed reference signals to generate discrete samples, and means for extracting the data from said samples characterized by:
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reference signal generator means for generating time reversed-time multiplexed reference signals; a time-multiplexed convolver for convolving said input signal and said time reversed-time multiplexed reference signals to generate M time multiplexed samples where M is equal to the number of orthogonal keying functions of said received M-ary orthogonal keying data modulated signal; demultiplexer means for separating said time multiplexed samples into M discrete samples; and means for comparing said M discrete samples to extract said data. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A spread spectrum communication system comprising:
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transmitter means for transmitting a pseudo random noise, phase modulated signal having a predetermined chip rate and modulated with data desired to be sent; receiver input means for generating a convolver input signal at a predetermined intermediate frequency in response to receiving said pseudo random noise, phase modulated signal; reference signal generator means for generating time reversed-time multiplexed reference signals having said same pseudo random noise phase modulated signal in a time reversed sequence; time-multiplexed convolver means for convolving said convolver input signal with said time reversed-time multiplexed reference signal to generate time multiplexed output samples; demultiplexer means for separating said time multiplexed output samples to generate discrete samples, each discrete sample corresponding to one of said binary phase modulations; and means for comparing the amplitudes of said discrete samples to recover said data. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38)
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Specification