GB598203A - Improvements in apparatus for comparing frequencies of electric oscillations - Google Patents

Abstract

598,203. Automatic control systems for oscillation generators. BRITISH BROADCASTING CORPORATION, GOURIET, G. G., and HAMMANS, R. H. Aug. 1, 1945, No. 19831. [Class 38 (iv)] [Also in Group XXXVI] For frequency and/or phase comparison of widely different frequencies, the lower frequency is changed into pulses of duration comparable with a half-cycle of the higher frequency and are applied with the higher frequency oscillations to charge a condenser in accordance with the degree of their coincidence so that the condenser charge varies cyclically at the rate at which coincidences occur. An oscillation, e.g. of 1000 kc./sec., is applied at GH to an amplifier V2 whose output includes a condenser 24, so that the anode of valve V1 is made alternately positive and negative. An oscillation, e.g. of frequency 1000 c./sec., is applied at AB to develop pulses on the grid of valve V1. The valve V1 conducts when its anode and grid are both positive, so that condenser 24 acquires a charge dependent on the degree of coincidence of the pulses at CD and the oscillations at GH. Movement of the meter 29 indicates a wander of phase or frequency. The current through the meter may be used to correct the frequency of the oscillator supplying GH by varying the bias of a reactance valve shunting the frequencydetermining circuit. Specification 596,741, [Group XXXVI], is referred to.