GB760824A - Improvements in or relating to pulse synchronising systems in pulse-actuated electronic apparatus - Google Patents

Abstract

760,824. Pulse. generator synchronizing systems. NATIONAL RESEARCH DEVELOPMENT CORPORATION. March 28, 1955 [Jan. 13, 1954], No. 1051/54. Class 40(6) A pulse, synchronizing system for pulse actuated electronic apparatus employs a standing wave as a synchronizing signal which is transmitted to pulse generators of the apparatus to control and synchronize the timing of the pulses generated by the generators. By this means the phase delay which would normally occur when pulses of very short duration are transmitted down a delay line for synchronizing purposes is avoided since the standing wave is arranged to have only small differences in amplitude along the transmission path and has the same phase at all points of the path. The transmission line comprises a cable to which a sinusoidal voltage is applied the cable being divided into sections of less than one half wave-length at the sinusoidal frequency the sections being terminated in impedances such that a standing wave of constant phase throughout the cable lengths is obtained. It is shown that if each section of the cable has an electrical length of approximately #/3 radians a variation in voltage of only some 13 per cent will occur along the length of the cable. A number of such cable sections may be connected together in series the unconnected ends of end sections of cable being terminated in impedances such that the ,ends are of the same voltage thus these ends may be connected together so that the cable provides a ring main for feeding the standing waves to the various items of electronic equipment in the apparatus. At the various items of equipment means are provided for generating a synchronizing pulse at some identifiable point of the sinusoidal wave-form, for example when the voltage changes from negative to positive. Figs. 3 and 4 show that if the end sections of the transmission line are terminated in inductive reactances of value #3 jz0 where z0 is the characteristic indepedance of the line and if the intermediate sections of the cable have a terminating impedance of one half this value then the required variation in voltage along the cable which should not exceed 13 per cent is obtained and the standing wave will have the same phase at all points along the cable. The terminating impedances of the ends of sections of the cable are calculated to be equivalent to the cable lengths which are omitted but which would carry that part of the standing wave. Alternatively, equivalent filter networks could be used.