Quadrature Amplitude Modulation! Theoretically, this circuit modulates 2 bit data into 4-QAM. Digital data is fed in parallel into op amps that control the amplitude of two sinusoids, 90 degrees out of phase. A digital 1 represents full positive amplitude, while a 0 represents negative amplitude. This results in quadrature phase shift keying (QPSK) that functionally serves as 4-QAM. I could go into more detail, as well as missing features like a pilot tone that allows the receiver to sync phases with the transmission and decode which bits are currently being sent.
Comments and suggestions are greatly appreciated!!
