GB566026A - Improvements in radio direction-finding systems - Google Patents

Abstract

566,026. Wireless direction-finding systems. JEFFERSON, H. March 20, 1942, No. 3756. [Class 40 (v)] A wireless direction-finding system of the kind in which an aerial A of variable directivity feeds a receiver R, the output of which modulates the intensity of the beam in a cathode-ray tube, is provided with two timebase circuits TB1, TB2 associated respectively with the X and Y deflecting members of the tube, and means for varying the tuning of the input circuit over a wide range in synchronism with the operation of one time-base circuit and for varying the directivity of the aerial system in synchronism with the operation of the other. The time-base circuits produce line-scanning of the beam, which is increased in brightness as the frequency to which the receiver is tuned passes through that of an incoming signal, so that a trace such as that shown in Fig. 3 is produced, in which S<1>, S" represent two transmitting stations operating at different frequencies. The bearings of these stations are indicated by the points b<1>, b<11>, at which the cathode-ray is extinguished as the aerial reception pattern passes through a null position. The input circuit may include a wide-band radio-frequency amplifier, a frequency changer, and a local oscillator, the frequency of which is variable over a corresponding band, for example, by a reactance valve driven from the time-base circuit or by a variable reactance driven by a motor which synchronously controls the time-base circuit. The aerial system may comprise a rotating loop, as shown, an Adcock system with a goniometer, or a spaced aerial system with phasing means, as described in Specification 237,906, [Class 40 (v)]. The timebase circuit may comprise a multivibrator variable frequency system, a reactance valve variable frequency circuit, or a motor-driven variable condenser or inductance.