GB607098A - Pulse discriminator - Google Patents

Abstract

607,098. Pulse discriminating circuits. STANDARD TELEPHONES & CABLES, Ltd. Jan. 25, 1946, No. 2542. Convention date, June 19, 1944. [Classes 40 (v) and 40 (vi)] A receiver for pulses having a given repetition frequency and a given ratio of pulse width to period comprises a ringing circuit tuned to the pulse repetition frequency or a harmonic thereof to give an output of amplitude dependent on pulse width, and means for selecting a portion of the output at a given amplitude level and applying it to open a gating circuit at the times of arrival of the wanted pulses. As shown in Fig. 2, incoming pulses are applied through a limiter 11 to a ringing circuit 21, tuned to the pulse repetition frequency, or a harmonic thereof. The output of amplitude dependent on the pulse width, is applied through a phase shifter 3 to two gate-clipper circuits 4, 5 in parallel, each comprising two clipper valves in cascade. Gate clipper 4 is adjusted to pass a section of the wave taken between levels (1), (2), Fig. 3 (c), below the amplitude of the wave 14c produced by the wanted pulses. The section of the wave between levels (3), (4), above the amplitude of the wave 14, taken by gate clipper 5, is inverted in phase by amplifier 31, and mixed at 7 with the output of gate clipper 4. The output of mixer 7, containing pulses corresponding to waves of amplitude between levels (1) and (3), Fig. 3 (c), is fed through low-pass filter 8 to one grid of gating valve 34, thus enabling the wanted pulses in the input fed to the other grid to pass to the demodulator 10.