Power line carrier communication systems usually use quadrature modulation to effectively cancel out-band signals and in-band interfering signals to implement single-side-band (SSB) modulation and use M-QAM to implement high speed data transmission. The analysis and design can be simplified by considering quadrature modulation as the complex signal. The definition of the complex signal

real modulation and complex modulation

the complex low-pass signal representation of real bandpass signal

SSB complex modulation and demodulation

and the application of digital SSB Weaver complex modulation in the digitized carrier communication are described.