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Abstract

An n-dimensional direct sequence spread spectrum modulator (10) comprises a spreading sequence generator (21) for generating a set of n/2 substantially mutually orthogonal spreading sequences. The spreading sequences each comprises combinations of the real and imaginary parts of complex sequences. A first frequency spreading arrangement (24,26) comprises a first input (24.1,26.1) for a first set of n/2 parallel input data streams (d.sub.1 (t) d.sub.2 (t)), a second input (24.2, 26.2) for the set of spreading sequences and an output (24.3, 26.3). Respective input data streams are associated with respective spreading sequences in the set of spreading sequences. A second frequency spreading arrangement (28,30) comprises a first input (28.1, 30.1) for a second set of n/2 parallel input data streams (d.sub.3 (t), d.sub.4 (t)), a second input (28.2, 30.2) for the set of spreading sequences and an output (28.3, 30.3). Respective input data streams being associated with respective spreading sequences in the set of spreading sequences. A quadrature modulator (42) comprises a first input (36.1) and a second input (38.1) and an output (40). The first input (36.1) is connected to the output of the first frequency spreading arrangement and the second input (38.1) is connected to the output of the second frequency spreading arrangement. An associated demodulator is also disclosed.

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