Method and apparatus for quadrature multi-pulse modulation of data for spectrally efficient communication

The combination of a modulator and a demodulator comprising:

• a modulator, said modulator modulating, during a series of signaling intervals, at least three data signals, each including a digital value for each signaling interval, the modulator comprising developing means for developing, for each data signal, a pulse of a predetermined shape, and combining means for combining the pulses and the data signals for form a single combined signal including, in each signaling interval, signal components bases on the pulses and on a digital value from each data signal, at least two of the signal components overlapping in time and in frequency;
• a demodulator comprising a receiving means for receiving the modulated signal, and demodulating means coupled to the receiving means for demodulating the modulated signal and determining a digital value for each of at least one of the signals using a weighted integration of the corresponding one of said pulses;
• and
• modulating means for modulating the combined signal onto a carrier frequency to thereby form a modulated signal,
• wherein the carrier frequency comprises first and second carrier components which are substantially orthogonal to one another, and wherein the modulating means modulates respective first and second portions of the combined signal onto each of the first and second carrier frequencies, and
• wherein the developing means develops a pulse of a predetermined shape for each of at least six data signals, and wherein the combining means forms each of the first and second portions of the combined signal based on at least three of the pulses and on the digital values of the at least three of the data signals.