GB406903A

GB406903A - Methods and apparatus for measuring distances

Info

Publication number: GB406903A
Application number: GB1778533A
Authority: GB
Original assignee: Submarine Signal Co
Current assignee: Submarine Signal Co
Priority date: 1933-06-22
Filing date: 1933-06-22
Publication date: 1934-03-08

Abstract

406,903. Indicating proximity of earth or other bodies. SUBMARINE SIGNAL CO. (LONDON), Ltd., 9, Victoria Street, London.-(Submarine Signal Co. ; 160, State Street, Boston, U.S.A.) June 22, 1933, No. 17785. [Class 37.] An aeroplane carries a cathode-ray oscillograph for timing the echo of a wireless signal reflected from the earth. The oscillograph plates 59, 61 may be charged in quadrature from a 1000-metre oscillator which is stabilized by the crystal 53, so that the cathode beam traces a circular path at one revolution per cycle of the oscillator. The signal is emitted by a 5-metre transmitter 54 once per cycle at instants when the paralyzing bias of battery 55 is overcome, at the peak of the low-frequency oscillation, by e.m.f. applied through the coupling 51. The echo is picked up by a receiving loop 63 and acts through the control grid 64 to produce a serration in the oscillograph trace. The echo-receiver is protected against the outgoing signal by a reversed coupling 22. In a modification (Fig. 4, not shown), the signal may be of wave-length 1000 metres and derived from the oscillator which energizes the oscillograph plates. It is continuously transmitted, and the cathode beam is suppressed except when its negative bias is overcome by the peak of the reflected. wave. The position of the cathode spot on a circular scale therefore indicates the phase difference between the emitted and received waves. In a further modification (Fig. 7, not shown), the lowerfrequency oscillation which controls the rotation of the oscillograph beam is also used to overmodulate the high-frequency transmitter, so that only a brief impulse is transmitted once per lower-frequency cycle, at a definite phase of the lower-frequency oscillation. The control electrode 64 may be replaced by an exterior coil. The fluorescent screen mav be covered by a mask having a circular slit, so that the trace of the cathode beam is visible only at the instant when the reply signal is received.