Servo system signal generation

Claim 1

THE SERVO SYSTEM SIGNAL GENERATION METHOD PRIMARILY FOR USE IN THE CONTROL OF ALTERNATING CURRENT RESISTANCE HEATING OPERATIONS OF THE TYPE IN WHICH A SUCCESSION OF VARIABLE DURATION CURRENT PULSES OF ALTERNATING SIGNS ARE CONDUCTED THROUGH A WORKPIECE POSITION, WHICH METHOD COMPRISES THE STEPS OF GENERATING A FIRST SIGNAL PROPORTIONAL TO THE VOLTAGE DEVELOPED ACROSS THE RESISTANCE OF THE WORKPIECE POSITION BY THE CURRENT PULSES, GENERATING A SECOND SIGNAL COMPRISING ALTERNATE RECTIFIED AND UNRECTIFIED HALF CYCLES OF THE FIRST SIGNAL BY SYNCHRONOUSLY RECTIFYING THE FIRST SIGNAL, AND GENERATING A THIRD SIGNAL BY INTEGRATING THE SECOND SIGNAL WITH RESPECT TO TIME WHEREBY THE THIRD SIGNAL IS INDICATIVE OF THE RESISTIVE VOLTAGE COMPONENT AND SUBSTANTIALLY INDEPENDENT OF THE INDUCTIVE VOLTAGE COMPONENT OF THE FIRST SIGNAL.