Device for scanning is not synchronized with energy by means of support, impulsfoermiger signals in synchronism with a clock generator

摘要

961,760. Electric selective signalling. PHILIPS ELECTRICAL INDUSTRIES Ltd. Oct. 30, 1962 [Nov. 2, 1961], No. 41013/62. Heading G4H. The duration of a pulse is encoded as a sequence of clock pulse, by a device not requiring the arrival of the pulse to be synchronised with the clock pulse generator, by applying to to two identical threshold devices 1, 3 (e.g. Schmitt triggers) the outputs of which control identical AND-gates 2, 4 to which are applied clock-pulses P 1 , the outputs of gates 2, 4 each being applied to an AND- gate 5 nad to an OR-gate 6, the outputs of which feed the first stages of shift registers 8, 9 respectively; the information stored in the first stage of register 8 being shifted to the second stage between adjacent clock pulses P 1 ; and means being provided for clearing to "ZERO", during the period between adjacent clock pulses,the "ONE" stored in the second register 9 during the previous period provided AND-gate 5 has stored a "ONE" in register 9 during either the same (first-said) period or one of the two preceding periods, but otherwise to transmit said "ONE" in register 9 to actuate an alarm device 12. Registers 8, 9 have three and two stages respectively and shifting is accomplished by clock pulses P 2 , P 3 respectively, of the same frequency as pulses P 1 but lagging in phase, P 3 later than P 2 later than P 1 . The shifting of a "ONE" in register 8 clears the second stage of register 9 to "ZERO". The alarm 12 is actuated if a "ONE" is present in the second stage of register 9 when a pulse P 3 occurs, i.e. if there were no "ONES" in register 8 on occurrence of the previous P 2 pulse. The system enables malfunctioning to be indicated without the alarm being actuated when the threshold levels of devices 1, 3 are (only) slightly different and a P 1 pulse arrives at gates 2, 4 when the input pulse signal level lies between the threshold levels. The sequence of pulses representing the input duration is fed to an unspecified unit 7.