Apparatus for synchronizing linear PN sequences
First Claim
1. Apparatus for synchronizing the linear PN sequences contained in the heavy noise background of a receiver data-carrying spread spectrum signal, comprising(a) demodulator means (106, 109) for separating from the received signal the noisy wideband PN spread spectrum component, and for generating a chip rate clock signal;
- (b) resident PN generator means (110) responsive to said chip rate clock signal for producing a replica of the PN sequence with arbitrary phase;
(c) running matrix inverse means (112) for obtaining the inverse (R-1) of the matrix (R) that is formed by n successive observations of the register of the resident generator;
(d) matrix vector product means (118) for multiplying the running inverse by a column vector of noisy chips, thereby to obtain a plurality of estimates of the phase vector;
(e) means (122) for smoothing and averaging the phase vector estimates, thereby to produce the smoothed phase vector (cj);
(f) dot product means (114) responsive to said smoothed phase vector and to the contents of the resident shift register for producing the properly phased PN sequence; and
(g) despreading means (108) for combining the noisy chips with the properly phased PN sequence, whereby the narrowband digital data carried by the spread spectrum signal may be recovered.
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Abstract
A system and method are disclosed for synchronizning the linear PN sequences contained in a received spread spectrum signal, characterized by the provision of a resident PN generator that is responsive to the chip rate clock for producing a replica of the PN sequence with arbitrary phase, a running matrix inverse of the matrix (R) formed by n successive observations of the register of the resident generator, and a matrix vector product device for multiplying the running inverse by a column vector of noisy chips, thereby to obtain a plurality of estimates of the phase vector. These estimates are smoothed and averaged to produce the smoothed phase vector (cj) that is applied to one input of a dot product device that operates in conjunction with the contents of the shift register of the resident generator to produce the properly phased PN sequence, which sequence is then supplied to despreading means for combining the noisy chips with the properly phased PN sequence. The system may be used for range computation, if desired.
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Citations
13 Claims
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1. Apparatus for synchronizing the linear PN sequences contained in the heavy noise background of a receiver data-carrying spread spectrum signal, comprising
(a) demodulator means (106, 109) for separating from the received signal the noisy wideband PN spread spectrum component, and for generating a chip rate clock signal; -
(b) resident PN generator means (110) responsive to said chip rate clock signal for producing a replica of the PN sequence with arbitrary phase; (c) running matrix inverse means (112) for obtaining the inverse (R-1) of the matrix (R) that is formed by n successive observations of the register of the resident generator; (d) matrix vector product means (118) for multiplying the running inverse by a column vector of noisy chips, thereby to obtain a plurality of estimates of the phase vector; (e) means (122) for smoothing and averaging the phase vector estimates, thereby to produce the smoothed phase vector (cj); (f) dot product means (114) responsive to said smoothed phase vector and to the contents of the resident shift register for producing the properly phased PN sequence; and (g) despreading means (108) for combining the noisy chips with the properly phased PN sequence, whereby the narrowband digital data carried by the spread spectrum signal may be recovered. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. The method for synchronizing the linear PN sequences contained in the heavy noise background of a received data-carrying spread spectrum signal, comprising the steps of
(a) demodulating the received signal to separate therefrom the noisy widebank PN spread spectrum component and to generate a chip rate clock signal; -
(b) producing by resident PN generator means in response to the chip rate signal a replica of the PN sequence with arbitrary phase; (c) obtaining the running matrix inverse (Ro-1) of the matrix (R) that is formed by n successive observations of the shift register of the resident PN generator means; (d) multiplying the running inverse by a column vector of noisy chips, thereby to obtain a plurality of estimates of the phase vector; (e) smoothing and averaging the phase vector estimates to produce the smoothed phase vector (cj); (f) producing from the smoothed phase vector and the contents of the resident generator shift register a properly phased PN sequence; and (g) combining the noisy chips with the properly phased PN sequence, thereby to permit recovery of the narrowband digital data carried by the spread spectrum signal. - View Dependent Claims (12, 13)
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Specification