GB804734A - Means for phase discrimination of an alternating current signal - Google Patents

Abstract

804,734. Phase-sensitive circuits. NORDENKETAY CORPORATION. June 29, 1955 [Nov. 30, 1954], No. 18734/55. Class 38 (4). [Also in Group XL (c)] A phase discriminator for determining the in-phase or quadrature phase state or component of an A.C. signal A cos wt. +B sin wt. relative to a reference A.C. wave of equal frequency and predetermined phase comprises time controlled impedances 3, 7 controlled by the reference wave and an energy storage device, e.g. capacitor 5, between the impedances 3, 7. The latter may be alternately operated short circuits to earth made by a switch 8 (Fig. 2), synchronously operated from the reference source 12 by way of a phasing network 13 so that only half-cycles of the input component A cos wt. pass to the capacitor 5. This, across a resistor 6 produces an output signal as shown in Fig. 6c, due to the average D.C. output being zero, so that only the portion Y proportional to A is passed to the output 2 when subsequently the input is short circuited and the output shunt is open circuited. To determine the phase quadrature component B if any of the input wave the switch 8 is driven in phase quadrature. In each case the component in phase quadrature with the component desired to be accepted produces zero output from the capacitor 5 or storage device. The system may include an amplifier A. In modifications two pairs of triodes or diodes connected in parallel opposition constitute the input and output short-circuiting switch 8.