Method and apparatus for digital audio broadcasting and reception
US5315583A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 1991 |
| Grant date | May 24, 1994 |
| Priority date | — |
| Expiry date | Apr 11, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2001/0093
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A radio broadcasting system for a composite signal consisting of a frequency modulated (fm) analog signal and a multicarrier modulated digital signal is provided which is resistive to multipath degradation. The fm signal and the digital multicarrier modulated signal are fully coherent. The digital signal uses a plurality of carriers having a maximum amplitude at least 20 dB below the unmodulated fm signal. The multicarrier modulated signal is phase locked to a recovered analog fm pilot tone in the composite baseband spectrum of the fm signal which is at least 20 dB above the multicarrier modulated signal, which enables rapid and reliable acquisition of signal for coherent detection. In a specific embodiment the multicarrier modulated signal is a synthesized vector-modulated signal which is a quadrature phase shift keyed (QPSK) modulated set of synthesized carriers each occupying 9.5 kHz of spectrum replicated twenty-one times within a 199.5 kHz bandwidth with no more than two bits per vector. An efficient channel coding consisting of high efficiency block coding, such as BCH 255, 239 code, is employed in connection with time interleaving of bits to mitigate the effects of frequency…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.