Ibiquity Digital Corporation

Ibiguity Digital Corporation

E Glynn Walden

Brian William Kroeger

George Nicholas Eberl

Paul James Peyla

Jeffrey Scott Baird

Denise Maureen Cammarata

Richard Edward Martinson

A method for AM in-band-on-channel (IBOC) digital audio broadcasting (DAB) uses a center channel signal in a central frequency band of an AM radio channel, the center channel signal is modulated by first and second versions of the program material to be transmitted. Sub-carriers in a upper and lower sidebands of the AM radio channel are modulated with addition digitally encoded portions of the program material. The upper sideband lies within a frequency band extending from about &plus;5 k Hz to about &plus;10 kHz from a center frequency of the radio channel and the lower sideband lying within a frequency band extending from about &minus;5 k Hz to about &minus;10 kHz from the center frequency of the radio channel. The center channel signal the upper and lower sideband sub-carriers are transmitted to receivers. In a hybrid IBOC DAB version, the center channel signal includes a carrier which is analog modulated by the first version of the program material and additional sub-carriers modulated by the second version of the program material, wherein the additional sub-carriers are transmitted at a power spectral density level that is less than the power spectral density of the analog modulated carrier. In an all-digital version, the center channel signal includes two groups of sub-carriers modulated with the program material.

Method and apparatus for AM digital broadcasting

This invention provides a method of broadcasting including the steps of providing a broadcast signal in a central frequency band of an FM radio channel; providing a first plurality of sub-carriers in an upper sideband of the FM radio channel; providing a second plurality of sub-carriers in a lower sideband of the FM radio channel; modulating a first group of the first plurality of sub-carriers with a complementary punctured convolution coded encoded version of program material; modulating a first group of the second plurality of sub-carriers with the complementary punctured convolution coded version of the program material; and transmitting the broadcast signal, the first group of the first plurality of sub-carriers and the first group of the second plurality of sub-carriers. In an all-digital version of the invention, the central frequency band may include a plurality of sub-carriers transmitted at a lower power level than that of the sub-carriers in the upper and lower sidebands. These additional sub-carriers can be used to transmit additional data. Transmitters and receivers which utilized the method are also included.

FM in-band-on-channel digital audio broadcasting method and system

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Marlton, NJ, United States of America

E Glynn Walden