Apparatus for measuring the mean square value of an electrical signal from sampled signal magnitudes

Abstract

Abstract A VOLTMETER FOR MEASURING THE ROOT MEAN SQUARE OR MEAN SQUARE AMPLITUDE OF A VOLTAGE INCLUDES AN INPUT AMPLIFIER OF HIGH INPUT IMPEDANCE AND LOW OUTPUT IMPEDANCE, THE INPUT OF WHICH IS TO BE CONNECTED TO THE SIGNAL BEING MEASURED. THE INSTANTANEOUS VOLTAGE OF THE OUTPUT OF THE AMPLIFIER IS SAMPLED AT DISCRETE TIMES AND A SERIES OF SIGNALS ARE PRODUCED WHOSE HEIGHTS AND LENGTHS ARE BOTH PROPORTIONAL TO THE VOLTAGE OF THE SIGNAL BEING MEASURED. THE SIGNALS PRODUCED AFTER SAMPLING, ARE TRIANGULAR PULSES AND, MORE SPECIFICALLY, ARE TRIANGULAR PULSES OF RIGHT-ANGLED TRIANGLE CONFIGURATION. THE SERIES OF SIGNALS IS CONVERTED INTO A PULSE WAVEFORM CONSISTING OF A SERIES OF PULSES OF THE SAME POLARITY WITH EACH PULSE HAVING AN AREA PROPORTIONAL TO THE SQUARE OF THE AMPLITUDE OF THE SIGNAL FROM WHICH IT WAS FORMED. AN INTEGRATOR RECEIVES THE PULSES FORMING THE PULSE WAVEFORM AND A SIGNAL DERIVED FROM ITS OWN OUTPUT SO AS TO PROVIDE A D.C. VOLTAGE OUTPUT WHICH IS EITHER PROPORTIONAL TO THE MEANS AREA UNDERNEATH THE WAVEFORM AND, HENCE, TO THE MEAN SQUARE VALUE OF THE VOLTAGE OF THE SIGNAL BEING MEASURED, OR, BY SAMPLING THE INTEGRATOR OUTPUT SIGNAL IN A MANNER SIMILAR TO THAT USED AFTER THE INPUT AMPLIFIER, PROPORTIONAL TO THE ROOT OF THE MEAN AREA UNDERNEATH THE WAVEFORM AND TO THE ROOT MEAN SQUARE OF THE VOLTAGE OF THE SIGNAL BEING MEASURED.

Inventors

• 👤 Eric Metcalf
• 👤 Anthony John Ley

Bibliographic Details