GB628615A - Improvements in and relating to the measurement of phase distortion in electrical circuits - Google Patents

Abstract

628,615. Phase difference measurements. GENERAL ELECTRIC CO., Ltd., and ESPLEY, D. C. Dec. 23, 1946, No. 37716. [Class 37] Apparatus for measuring the phase shift at different frequencies produced by a circuit. e.g. a line, comprises oscillators 11, 12, Fig. 2, producing frequencies f1, f2, of which the latter is variable, which are modulated by a lower frequency f0 and applied to the circuit 16 under test, the frequencies f1,f2 being separated at the output demodulated at 23, 19 and applied alternately over switch 22 to a pulse generator 25 which produces a pulse at a predetermined point of each cycle of the demodulated oscillations f0, the pulses being applied to a phase measuring device. If the device has a frequency attenuation characteristic as in Fig. 1, f1 is fixed at a value on the shoulder, and f2 is variable over the range B. Preferably, the output of demodulator 23 is applied as time base to a cathode-ray tube 26, and the derived pulses from 25 produce a trace, Fig. 3, on the cathode-ray tube in which the distance between the peaks 28, 29 is a measure of the phase difference.