AM compatible digital audio broadcasting signal transmision using digitally modulated orthogonal noise-like sequences

An apparatus for modulating noise-like waveforms into a multidimensional constellation comprising:

• a) means for generating a plurality of basis waveforms, said waveforms comprising multiple mutually orthogonal, continuous valued noise-like spreading sequences;
• b) means for formatting data to be transmitted;
• c) means for mapping amplitude modulation coefficients from said formatted data;
• d) means for modulating said basis waveforms with said amplitude modulation coefficients;
• e) means for adding said coefficient modulated waveforms to produce summed sets;
• f) means for modulating said summed sets in-phase or in-quadrature, or in-phase and in-quadrature, with the desired carrier signal;
• and
• g) means for combining said in-phase and/or in-quadrature modulated waveforms to produce a resultant digitally modulated signal.

A method of modulation in an AM channel wherein at least one set of basis waveforms is modulated by a first method of modulation and at least one set of basis waveforms is modulated by a second method of modulation, said first method of modulation comprising the steps of:

• a) generating a plurality of basis waveforms, said basis waveforms comprising shaped, orthogonalized noise-like spreading sequences;
• b) formatting data to be transmitted;
• c) mapping first and second sets of amplitude modulation coefficients from said formatted data;
• d) modulating a first set of said plurality of waveforms by said first set of amplitude modulation coefficients;
• e) modulating a second set of said plurality of waveforms by said second set of amplitude modulation coefficients;
• f) adding said first coefficient modulated set of waveforms together to produce a first summed set;
• g) adding said second coefficient modulated set of waveforms together to produce a second summed set;
• h) modulating said first summed set of waveforms in-quadrature with the desired carrier signal;
• and
• i) modulating said second summed set of waveforms in-phase with the desired carrier signal, wherein said in-phase modulated waveforms comprise a first resultant digitally modulated signal;
• and wherein said second method of modulation comprises the steps of:
• a) generating the plurality of basis waveforms, said basis waveforms comprising shaped, orthogonalized noise-like spreading sequences;
• b) formatting the data to be transmitted;
• c) mapping a third set of amplitude modulation coefficients from said formatted data;
• d) modulating a third set of said plurality of waveforms by said third set of amplitude modulation coefficients;
• e) adding said third coefficient modulated set of waveforms together to produce a third summed set;
• f) modulating said third summed set of waveforms in-quadrature with the desired carrier to produce a second resultant digitally modulated signal;
• and
• h) combining said in-quadrature modulated waveforms of said first and second modulation methods to produce a third resultant digitally modulated signal.