Pseudo Noise Coded Communication Systems
First Claim
1. An apparatus for pseudo noise (PN) code phase acquisition comprising:
- an oscillator;
an analog to digital converter adapted to receive a baseband signal having a PN code phase, said analog to digital converter being adapted to sample said baseband signal at a rate controlled by said oscillator and to output a vector of sequential samples, each sequential sample having a length of 2N−
1, wherein the vector of sequential samples is permuted from the analog to digital converter to generate a permuted vector;
a fast Walsh transform engine adapted to perform a fast Walsh transform on the permuted vector and to output an output vector from the vector of sequential samples generated by the analog to digital converter; and
a peak detector adapted to detect the largest correlation with a target PN maximal length sequence having a length of 2N−
1 within the vector of sequential samples and determine a dominant peak in said output vector, wherein the dominant peak is unpermuted to map into the PN code phase.
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Abstract
Systems, apparatus and methods for acquiring code phase and multipath channel models in communication device. A fast Walsh transform engine is used to acquire a pseudo noise code phase and the pseudo noise code bit rate of a radiofrequency signal that has been broadcast. Multipath filter coefficients from the pseudo noise code phase and the pseudo noise code bit rate are recovered. A pseudo noise generator is initialized with the pseudo noise code phase acquired during the fast Walsh transform step. The pseudo noise code phase and pseudo noise code bit rate are tracked by a phase locked loop so that communication with the radiofrequency signal is maintained. Then, the received noise code phase and pseudo noise code bit rate are despread so that any data in the radiofrequency signal is recovered.
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Citations
11 Claims
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1. An apparatus for pseudo noise (PN) code phase acquisition comprising:
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an oscillator; an analog to digital converter adapted to receive a baseband signal having a PN code phase, said analog to digital converter being adapted to sample said baseband signal at a rate controlled by said oscillator and to output a vector of sequential samples, each sequential sample having a length of 2N−
1, wherein the vector of sequential samples is permuted from the analog to digital converter to generate a permuted vector;a fast Walsh transform engine adapted to perform a fast Walsh transform on the permuted vector and to output an output vector from the vector of sequential samples generated by the analog to digital converter; and a peak detector adapted to detect the largest correlation with a target PN maximal length sequence having a length of 2N−
1 within the vector of sequential samples and determine a dominant peak in said output vector, wherein the dominant peak is unpermuted to map into the PN code phase. - View Dependent Claims (2, 3, 4, 5)
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6. A method for acquiring a sub-PN-bit phase of a M-sequence PN coded pulsed signal a pseudo noise (PN) code phase encoded in a beacon signal transmitted from a remote radiofrequency transceiver, comprising:
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generating a vector of sequential samples from the beacon signal after it has been digitized; permuting the vector of sequential samples; generating a permuted vector; performing a fast Walsh transform on said permuted vector, wherein each sequential sample of the permuted vector has a length of 2N−
1;detecting a dominant peak of the fast Walsh transform within the vector of sequential samples by detecting the largest correlation with a target PN maximal length sequence having a length of 2N−
1;umpermuting the detected dominant peak; and mapping the detected dominant peak into the PN code phase, the dominant peak corresponding to the beacon signal indicative of the signal to be acquired. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification