The use of the Hilbert transform to double the information rate in spread-spectrum communications

A new technique which provides increased capacity in a direct-sequence spread-spectrum system is described. The technique makes use of the Hilbert transform of the spreading sequence to provide an extra degree of orthogonality. The crosstalk between the various signals is shown to be negligible, and the performance of the system when operating in the presence of a tone interfering signal is derived. Methods of achieving synchronization are discussed and experimental results showing all key waveforms are presented.