GB569474A - Improvements in or relating to arrangements for generating and observing electric pulses - Google Patents

Abstract

569,474. Valve generating circuits. STANDARD TELEPHONES & CABLES, Ltd., LEVY, M. M., and ELLIOTT, T. W. Jan. 29, 1943, No. 1536. [Class 40 (v)] [Also in Group XXXVI] In an oscillograph for observing repeated pulses or other voltage variations, which are of short duration compared with the interval between them, the time base is provided by a sinsusoidal wave and only the substantially straight portion of the wave is effective, the oscillograph being blocked during the remainder of the cycle. In this way, the pulse may occupy a large fraction of the screen width. As shown in Fig. 1, the sinusoidal time-base voltage is generated at O and is passed through a phase-adjuster PS1 and amplifier A2 to the horizontal deflecting-plates H1, H2 of the oscillograph CRT. The pulses to be observed are applied between the vertical deflecting- plates VI, V2. The sine-wave from O is also passed through a second phase-adjuster PS2 to a pulse generator PG and amplifier A1. The pulse generated at PG is of the form B, Fig. 2, and is fed to an artificial line or delay network DN short-circuited or open-circuited at the far end y to provide a delayed reflected pulse at the near end. The combination produces positive and negative pulses C1, C2 each of which has a width equal to twice the delay of the network. These pulses are applied to a grid G in the tube CRT, to block the beam except during the pulse Cl. By adjustment of the phase-shifters, this period of effective operation of the tube CRT may be arranged to coincide with the substantially straight portion P of the time-base wave A and with the arrival on V2 of the pulses to be observed. The frequency of the oscillator 0 is synchronized with that of the' incoming pulses by hand or by known automatic means. Pulses D1, D2 for use in locating obstacles &c. may be derived from a tapping T on the line DN, the pulse width being equal to twice the delay time between the point T and the far end y of the line. The negative pulse D2 may be suppressed in the amplifier A3, and the shape of the positive pulse D1 may be observed by connecting the terminals 1, 2. Recurrent irregularities F in a voltage wave may be observed in a similar manner.