PSK modulator with reduced spectrum occupancy

Apparatus for phase modulating a carrier signal with a digital data signal comprising in combination:

• filter means for receiving and filtering a digital data signal to provide a filtered digital data signal;
• carrier signal generator means for providing a first and a second carrier signal in phase quadrature with each other;
• means for phase modulating said first carrier signal with said filtered digital data signal;
• means for modulating said second carrier signal with said filtered digital data signal only during data transitions of said filtered digital data signal so as to provide a modulated second carrier signal which complements the modulated first carrier signal;
• a signal combiner connected to receive the modulated first and second carrier signals and for providing a combined modulated signal;
• and
• amplitude limiting means connected to receive said combined modulated signal for limiting the amplitude variations thereof.

Apparatus for modulating a carrier signal with a digital data signal comprising in combination:

• carrier signal generator means for providing a first and a second carrier signal in phase quadrature with each other;
• first channel means for modulating said first carrier signal as a function of said digital data signal;
• a second channel means including combining means for modulating said second carrier signal with said digital data signal only during data transitions of said digital data signal so as to provide a modulated second carrier signal which complements the modulated first carrier signal, and for combining the modulated first and second carrier signals;
• and
• limiting means for limiting the amplitude variations in the combined modulated signals.