schaltungsanordnung to verzoegerungsfreien education free of waehlbaren number of ausgangsimpulsen per unit of time from a small number of successive incoming eingangsimpulsen per unit of time

摘要

1,132,104. Modifying pulse trains; pulse radar. MARCONI CO. Ltd. 30 Dec., 1965, No. 7085/65. Headings H3T and H4D. A circuit receives two pulse trains of different frequency and removes pulses from the higher frequency train so that the number in unit time is the same as that in the lower frequency train; the pulses are removed by a gate controlled alternately by the two trains. Such an arrangement is useful in stepping down the repetition rate of a primary radar to the maximum permissible for an associated secondary radar. In Fig. 2 input pulses (at the higher rate) are applied to a gating circuit G1, G2 (normally open) and through a delay line D to a bi-stable circuit C1, C2 which is thereby changed over to cut off the gating transistor G1. A relaxation oscillator comprising a unijunction transistor T1 operates as the lower frequency input and until this has changed the bi-stable circuit back to its original state no pulses can pass through the gate. The delay period may be arranged to shut the gate at the end of the input pulse or just after the leading edge thereof. In another form (Fig. 4, not shown) the input pulses and those from the unijunction are applied directly to the opposite sides of a bistable circuit (CG1, CG2), the delay line and gate being omitted. An input pulse cannot produce an output from the bi-stable circuit unless this has been changed over by a pulse from the unijunction since the last input pulse was received. The output pulses from the bi-stable circuit are differentiated (at DC) and used to trigger a pulse generator (PG) to produce the desired output. In this case, if the input pulse frequency is an integral multiple of the unijunction relaxation frequency, the latter can be synchronized with the input through a common resistor (T3).