Apparatus for measuring the difference in phase between two signals of the same frequency, one having noise associated therewith

Abstract

Abstract APPARATUS FOR MEASURING THE DIFFERENCE IN PHASE, FROM 0* TO 180*, BETWEEN A NOISE-FREE SIMUSOIDAL REFERENCE SIGNAL OF A PREDETERMINED FREQUENCY AND AN UNKNOWN SINUSOIDAL SIGNAL OF THE SAME FREQUENCY BUT HAVING NOISE ASSOCIATED THEREWITH. THE UNKNOWN AND REFERENCE SIGNALS ARE APPLIED TO RESPECTIVE LIMITERS AND CONVERTED TO SQUAREWAVE PULSE TRAINS WHICH TRIGGER, RESPECTIVELY, A SAMPLEPULSE GENERATOR AND A RAMP GENERATOR. SAMPLING PULSES ARE PRODUCED BY THE PULSE GENERATOR AND USED TO SAMPLE A TRAIN OF RAMP VOLTAGE SIGNALS APPLIED TO A SAMPLE-ANDHOLD CIRCUIT BY THE RAMP GENERATOR. THE SAMPLED SIGNAL PORTIONS ARE CONVERTED IN THE SAMPLE-AND-HOLD CIRCUIT TO A CONTINUOUS VOLTAGE SIGNAL OF VARYING AMPLITUDE REPRESENTATIVE OF THE PHASE DISPLACEMENT BETWEEN THE UNKNOWN AND REFERENCE SIGNALS. THE NOISE CONTENT OF THE CONTINUOUS VOLTAGE SIGNAL IS REDUCED BY A LOW-PASS FILTER TO PROVIDE AN ANALOG SIGNAL REPRESENTATIVE OF THE PHASE DISPLACEMENT BETWEEN THE REFERENCE AND UNKNOWN SIGNALS. TO PROVIDE A DIGITAL REPRESENTATION, THE ANALOG SIGNAL IS APPLIED TO AN ANALOG COMPARATOR TOGETHER WITH THE TRAIN OF RAMP VOLTAGE SIGNALS. THE COMPARATOR COMPARES THE SIGNALS AND PRODUCES A SQUARE-WAVE PULSE TRAIN REPRESENTING THE PHASE DISPLACEMENT BETWEEN THE UNKNOWN SIGNAL AND THE REFERENCE SIGNAL, WHICH PULSE TRAIN IS USED TO GATE CLOCK SIGNALS T A DIGITAL COUNTER WHICH PROVIDES A DIGITAL INDICATION OF THE AMOUNT OF PHASE DISPLACEMENT.

Inventors

• 👤 James F Teixeira

Bibliographic Details