Notch filtering a spread spectrum signal using fourier series coefficients
First Claim
1. A method for generating, from a first pseudo-noise (PN) sequence, a spread-spectrum signal having a bandwidth, with spectrum within the bandwidth having at least one notch at a selected band of frequencies, comprising the steps of:
- generating a first plurality of Fourier series coefficients from the PN sequence;
generating a first modified set of the first plurality of Fourier series coefficients by deleting, corresponding to each selected band of frequencies, a subset of the first plurality of Fourier series coefficients;
generating, from the first modified set of Fourier series coefficients a first spreading signal; and
transmitting the spread-spectrum-processed message data as the spread-spectrum signal over a communications channel.
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Accused Products
Abstract
A transmitter and receiver for spread spectrum communications using a Fourier series coefficients module, a notch gate, a fast Fourier transform module, and memory. The Fourier series coefficient module generates magnitude and phase values of a Fourier series. The notch gate notches the Fourier series coefficients at selected bands of frequencies. The selected band of frequencies are chosen so as not to provide interference with a preexisting user such as a cellular user, microwave user, or other radio communications. The fast Fourier transform generates from the notched Fourier series coefficients a spreading signal. The spreading signal has notches in its spectrum so as not to cause interference with the preexisting users. At the transmitter, the spreading signal is used to spread-spectrum process message data to generate a spread-spectrum signal for transmitting over a communications channel. At the receiver, the spreading signal is used to despread a receive spread-spectrum signal. At the receiver, the receive spread-spectrum signal has the advantage that the preexisting users are notched out and not part of the despread signal and therefore not part of the interference in the receiver detection circuits.
48 Citations
46 Claims
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1. A method for generating, from a first pseudo-noise (PN) sequence, a spread-spectrum signal having a bandwidth, with spectrum within the bandwidth having at least one notch at a selected band of frequencies, comprising the steps of:
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generating a first plurality of Fourier series coefficients from the PN sequence; generating a first modified set of the first plurality of Fourier series coefficients by deleting, corresponding to each selected band of frequencies, a subset of the first plurality of Fourier series coefficients; generating, from the first modified set of Fourier series coefficients a first spreading signal; and transmitting the spread-spectrum-processed message data as the spread-spectrum signal over a communications channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method using a first modified set of a first plurality of Fourier series coefficients, for generating a spread-spectrum signal having a bandwidth with spectrum within the bandwidth having at least one notch at a selected band of frequencies, with the first modified set of the first plurality of Fourier series coefficients generated from a first plurality of Fourier series coefficients of a first pseudo-noise (PN) sequence by deleting, corresponding to each selected band of frequencies, a subset of the first plurality of Fourier series coefficients, the method comprising the steps of:
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generating from the first modified set of Fourier series coefficients a first spreading signal; spread-spectrum processing message data with the first spreading signal; and transmitting the spread-spectrum processed message data as the spread-spectrum signal over a communications channel. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An apparatus for transmitting, from a first pseudonoise (PN) sequence, a spread-spectrum signal having a bandwidth, with spectrum within the bandwidth having at least one notch at a selected band of frequencies, comprising:
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means for generating a first plurality of Fourier series coefficients from the PN sequence; means for generating a first modified set of the first plurality of Fourier series coefficients by deleting, corresponding to each selected band of frequencies, a subset of the first plurality of Fourier series coefficients; means for generating from the first modified set of Fourier series coefficients a first spreading signal; means for spread-spectrum processing message data with the first spreading signal; and means for transmitting the spread-spectrum-processed message data as the spread-spectrum signal over a communications channel. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A transmitter using a first modified set of a first plurality of Fourier series coefficients, for generating a spread-spectrum signal having a bandwidth with the bandwidth having at least one notch at a selected band of frequencies, with the first modified set of the first plurality of Fourier series coefficients generated from a first plurality of Fourier series coefficients of a first pseudo-noise (PN) sequence by deleting, corresponding to each selected band of frequencies, a subset of the first plurality of Fourier series coefficients, said transmitter comprising:
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a signal generator for generating from the first modified set of Fourier series coefficients a first spreading signal; a spreader coupled to said signal generator for spread-spectrum processing message data with the first spreading signal; and an antenna coupled to said spreader for transmitting the spread-spectrum processed message data as the spread-spectrum signal over a communications channel. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46)
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Specification