Patent GB-609528-A (GB)
Title: Improvements in or relating to oscilloscope apparatus and wave generators suitable for use in radio location and other systems
IPC: H03K4/06
Filed: 1946-03-11
Abstract: 609,528. Saw-tooth or pulse generating circuits; radiolocation. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. March 11, 1946, No. 7588. Convention date, June 27, 1942. [Classes 40 (vi) and 40 (vii)] In cathode-ray oscilloscope apparatus for use in radiolocation or like systems where it is required to compare a signal with an index or. timing mark, a triangular waveshape sweep voltage is generated to obviate switching, by charging and discharging a condenser at a substantially uniform rate and displaying the signal and index marks on the forward and fly-back traces respectively of the oscilloscope either the charging or discharging circuit (or both) for the condenser including a constant current circuit. In Fig. 9, a triangular sweep voltage is. applied from a generator 100 to the horizontal deflecting plates of an oscilloscope CRO, echo pulses as shown at 10 in Fig. 2 and marking pulses 11 in Fig. 2 being applied to the vertical deflecting plates from a receiver VR and a timing unit TMC. The condenser C1 may be charged through a series connected inductor L1 and shunt connected capacitor C2, Fig. 3, and discharged through a similar constant current network L2, C3, the initiation of the discharge being controlled by a gas-discharge triode to which synchronizing pulses may be applied, the resonant frequencies of the networks L1, C2, L2, C3 being near the pulse repetition frequency. The charging network may be replaced by a pentode valve, Fig. 4 (not shown), adjusted to operate as a constant current device, the condenser to be charged being connected in the cathode circuit of the valve. In a further modification, Fig. 5 (not shown), the constant current discharging device comprises a temperature limited diode or another pentode valve, Fig. 5A (not shown). In a further modification, the discharge controlling constant current pentode, Figs. 6 and 6A (not shown), is included in the cathode to earth path of the gas-discharge valve, the charging path being via a temperature limited diode or a pentode valve. In Fig. 7, valves T1, T2 are connected in a single-stroke multi-vibrator circuit which is triggered by negative synchronizing pulses applied to condenser N, the period of operation of the miilti-vibrator being controllable by resistor R7. The resulting positive pulse at point A renders the valve T3 conducting and condenser C1 is charged, resistors R1, R9 and R6<111> being adjusted so that the condenser is charged at a constant rate. The negative pulse at point B is differentiated by network C13, R13 and the positive pulse therefrom triggers the single-stroke multi-vibrator circuit comprised by valve T4, resistor R11 being adjusted so that the pentode section of valve T4 operates as a constant current device through which condenser C1 is discharged; after a period of time determined by resistor R14, the valve T4 will reverse and be ready for the next pulse which initiates the discharging of condenser C1. A waveform such as shown in Fig. 2A may thus be generated. In a further modification, Fig. 8 (not shown), the discharging circuit multi-vibrator is comprised by two separate valves and the charging pentode obtains its H.T. supply direct instead of via one of the multi-vibrator valves.