Novel spread spectrum codec apparatus and method

Claim 1

A spread spectrum encoding apparatus for generating a code sequence comprising an ordered sequence of values from an ordered sequence of symbols, said encoding apparatus comprising: means for receiving an input signal comprising predetermined number of symbols from said ordered sequence of symbols; memory means for storing at least a portion of a first spread spectrum basis having a multiplier μ comprising one or more channel sequences, the m th said channel sequence comprising an array of numerical values w p , where p runs from 0 to L-1, wherein each said channel sequence being of length L, the number of said stored channel sequences being less than or equal to μ, wherein ##EQU6## where (*) denotes complex conjugation, E is a constant, μ is a positive integer, and the sum is performed over all values of p for which w p (i) and w p+ μq (j) are non-zero; clock means for generating a sequence of timing signals; control means connected to said memory means and said receiving means for generating a sum array comprising an ordered array of numerical values β(k), for k=0 to (L-1), said control means comprising means for selecting a said channel sequence corresponding to each of said predetermined number of symbols, for multiplying said selected channel sequence by a numerical value depending on said corresponding received symbol, and for adding corresponding values of said multiplied channel sequences to form said ordered array β(k); means for storing a spread spectrum array comprising an ordered array of numerical values α(k) for k=0 to L-1; means connected to control means and said spread spectrum array storing means for combining said sum array with said spread spectrum array comprising means for adding β(k) to α(k), said combining means being responsive to said clock means having generated μq said timing signals, where q is a positive integer; and shifting means for outputting α(L-1) as the next value in said generated code sequence, for replacing α(k) by α(k-1) for k=1 to (L-1), and for replacing α(0) by 0, said shifting means being connected to said spread spectrum array storing means and being responsive to said clock means having generated a said timing signal.

Claim 12

A method for encoding a spread spectrum signal comprising the steps: receiving an input signal comprising an ordered sequence of symbols; storing at least a portion of a first spread spectrum basis having a multiplier μ comprising one or more channel sequences, the m th said channel sequence comprising an array of numerical values w p where p runs from 0 to L-1, wherein each said channel sequence is of length L, the number of said stored channel sequences being less than or equal to μ, wherein ##EQU8## where (*) denotes complex conjugation, E is a constant, μ is a positive integer, and the sum is performed over all values of p for which w p (i) and w p+ μq (j) are non-zero; generating a sequence of timing signals; generating a sum array comprising an ordered array of numerical values β(k), for k=0 to (L-1), said control means comprising means for selecting a said channel sequence corresponding to each of said predetermined number of symbols, for multiplying said selected channel sequence by a numerical value depending on said corresponding received symbol, and for adding corresponding values of said multiplied channel sequences to form said ordered array β(k); storing a spread spectrum array comprising an ordered array of numerical values α(k) for k=0 to L-1; combining said sum array with said spread spectrum array comprising means for adding β(k) to α(k), said combining means being responsive to said clock means having generated μq said timing signals, where q is a positive integer; and at each timing signal, outputting α(L-1) as the next value in said generated code sequence, for replacing α(k) by α(k-1) for k=1 to (L-1), and for replacing α(0) by 0.

Claim 13

A method for encoding a spread spectrum signal comprising the steps: receiving an input signal comprising an ordered sequence of symbols; storing at least a portion of a first spread spectrum basis having a multiplier μ comprising one or more channel sequences, the m th said channel sequence comprising an array of numerical values w p where p runs from 0 to L-1, wherein each said channel sequence is of length L, the number of said stored channel sequences being less than or equal to μ, wherein ##EQU8## where (*) denotes complex conjugation, E is a constant, μ is a positive integer, and the sum is performed over all values of p for which w p (i) and w p+ μq (j) are non-zero; generating a sequence of timing signals; generating a sum array comprising an ordered array of numerical values β(k), for k=0 to (L-1), said control means comprising means for selecting a said channel sequence corresponding to each of said predetermined number of symbols, for multiplying said selected channel sequence by a numerical value depending on said corresponding received symbol, and for adding corresponding values of said multiplied channel sequences to form said ordered array β(k); storing a spread spectrum array comprising an ordered array of numerical values α(k) for k=0 to L-1; combining said sum array with said spread spectrum array comprising means for adding β(k) to α(k), said combining means being responsive to said clock means having generated μq said timing signals, where q is a positive integer; and at each timing signal, outputting α(L-1) as the next value in said generated code sequence, for replacing α(k) by α(k-1) for k=1 to (L-1), and for replacing α(0) by 0.