Ringing, tone, and cadence requirements for nonswitched loads in digital central offices

The author describes the residual load signals most often encountered and shows an example of a state-of-the-art residual ringing, tone, and cadence power plant based on digital and PWM (pulse-width modulation) techniques which operates in a space and cost-efficient manner. This plant is expandable to meet the need for increased output capacity, which is frequently not discovered until after the unit is placed in service. After describing residual ringing, tones, and cadences, the author gives the design objectives and, finally, presents the complete system