The use of tone modulation over complex carrier channels

The need for tone modulation of power line carrier channels is shown to arise from the necessity of conserving spectrum space. Different types of modulation are analyzed to show what frequencies actually are transmitted. The characteristics of carrier channels are discussed and the results of uneven attenuation and phase displacement over the transmission bandwidth are pointed out. Methods of improving carrier channel characteristics are included, as well as recommendations for selection of tone equipment to avoid the adverse effects of channel distortion.