Method and apparatus for digital audio broadcasting and reception
US5278826A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 1991 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | Apr 11, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04H2201/183
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A radio broadcasting system is provided for transmitting and receiving through free space a composite signal consisting of a frequency modulated (fm) analog signal and a multicarrier modulated digital signal which is especially adapted to be resistive to multipath degradation. The fm signal and the digital multicarrier modulated signal are fully coherent. Further according to the invention, the digital signal comprises a plurality of carriers having a maximum amplitude at least 20 dB below the unmodulated fm signal and preferably, 30 dB below the analog signal. The multicarrier modulated signal is phase locked according to the invention to the recovered analog fm pilot tone at 19 kHz 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 ve…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.