Circuit for modulating a sinusoidal waveform signal using digital pulse shaping

A circuit for generating a carrier whose frequency is determined by a value manifested by a digital data signal, comprising:

• a random access memory (RAM);
• a main controller coupled to said random access memory for generating a first data word representative of a base frequency and a second data word representative of an offset frequency, said main controller controlling a transfer of said first and second data words from said main controller to said random access memory;
• said main controller generating a manual load signal and a chip select signal;
• an oscillator control circuit coupled to said random access memory and said main controller, said oscillator control circuit receiving said chip select signal, said manual load signal and said digital data signal;
• numerically controlled oscillator means coupled to said oscillator control circuit;
• said oscillator control circuit, responsive to said chip select signal, passing said digital data signal through said oscillator control circuit to said numerically controlled oscillator means;
• said oscillator control circuit having direct access to said RAM and said numerically controlled oscillator means to allow said manual load signal to initiate a direct memory access transfer of said first and second data words from said oscillator control circuit to said numerically controlled oscillator means;
• said numerically controlled oscillator means, responsive to said digital data signal and said first and second data words, selectively generating either a first sinusoidal waveform signal having a first frequency or a second sinusoidal waveform signal having a second frequency different from said first frequency in accordance with the value of said digital data signal.