Patent ID: 6061387
Filing Date: 2000-05-09
Classification: H03M,H04B,H04H,H04J,H04L,Y02D

Abstract:
A method of communicating audio signals using Turbo Coding in a digital audio broadcast (DAB) system, the method comprising the steps of:encoding each audio signal according to the Turbo Code punctured to a code rate of 1/2 for transmission on a first path to a first satellite in a substantially geosynchronous orbit;combining a first pilot signal and a predetermined number of encoded audio signals using an orthogonal CDMA (OCDMA) modulator, said OCDMA modulator consisting essentially of a first set of orthogonal Walsh sequences to form a first turbo encoded broadcast signal;transmitting said first turbo encoded broadcast signal on said first path having said first pilot signal transmitted at a higher power than the encoded broadcast signal;encoding each interleaved audio signal according to the Turbo Code punctured to a rate of 1/2 for transmission on a second path to a second satellite;combining a second pilot signal and the interleaved encoded audio signals using another OCDMA modulator, said another OCDMA modulator consisting essentially of a second set of orthogonal Walsh sequences;transmitting said second turbo encoded broadcast signal on said second path having said second pilot signal transmitted at a higher power than the encoded broadcast signals;at a receiver:receiving said first and second turbo encoded broadcast signals;demodulating a selected audio channel from said first and second turbo encoded broadcast signals using orthogonal Walsh sequences using separate RAKE receivers so as to optimally combine audio signals for the selected audio channel from said first and second turbo encoded signals received from said first and second paths.