Method and apparatus for generating digitally modulated signals

A digital modulator comprising:

• a processor for receiving a serial data stream of digital signals to be modulated and for separating the serial data stream to into real and imaginary components;
• a rectangular to polar converter for receiving the real and imaginary components to produce a complex polar signal representing the serial data stream;
• a complex multiplier;
• an infinite impulse response filter for producing a carrier signal at a desired frequency;
• applying the complex polar signal and the carrier signal of the infinite impulse response filter to the complex multiplier to produce a modulated complex signal representative of the serial data stream of digital signals at a frequency of the carrier signal generated by the infinite impulse response filter;
• and
• means for extracting the real component of the modulated complex signal to produce a resultant digital signal representative of the serial data stream of digital signals.

A digital modulator comprising:

• a rectangular to polar converter for receiving real and imaginary components of a digital data stream to produce a complex polar signal representing the digital data stream;
• a complex multiplier;
• an infinite impulse response filter having an input representative of a frequency of a desired carrier signal, and comprising a multiplier, and a delay register in feedback to the multiplier to produce at an output a carrier frequency signal of a desired frequency;
• applying the complex polar signal and the output of the infinite impulse response filter to the complex multiplier to produce a modulated complex signal representative of the digital data stream at the desired frequency of the carrier frequency signal generated by the infinite impulse response filter, the modulated complex signal having real and imaginary parts;
• means for extracting the real part of the modulated complex signal to produce a resultant digital signal representative of the digital data stream;
• and,
• a digital to analog converter having an input for receiving the resultant digital signal, and an output for producing an analog signal representing the digital data stream modulated at the desired carrier frequency.