Patent GB-937169-A (GB)
Title: A device for measuring distortion of telegraph pulses
IPC: H04L12/26
Filed: 1960-04-06
Abstract: 937,169. Telegraphy. TESLA, NARODNI PODNIK. April 6, 1960 [April 7, 1959], No. 12204/60. Class 40 (3). In an arrangement for measuring the distortion of telegraph impulses, comprising a generator of measuring impulses, an electronic gate for the passage of the measuring impulses into two counters namely a decadic counter for units and a decadic counter for tens, coincidence circuits for the indications of units and tens, a zero-setting circuit for the two decadic counters, two functional switches and a trigger circuit, the two coincidence circuits for the indications of units and tens are connected to the decadic counters and operated by the trigger circuit in such manner that the coincidence circuits indicate the positions or settings of the decadic counters at the moment at which the impulse to be measured decays or approaches its end. With the switch A in the upper position for the measurement of the distortion of positive pulses received over the line L, and the switch B in the left-hand position, the differentiated leading edge of a received pulse triggers a circuit F to produce a positive pulse at f1 opening a gate H to pulses from a generator G operating at a frequency to provide 100 impulses during the normal period of a signal element. With the switch B in its left-hand position, a negative pulse on f1 at the end of an incoming positive impulse closes the gate H. The pulses are fed to a units counter N 1  controlling a tens counter N 2 . At the end of a signal element a pulse circuit F is triggered to pass a pulse over f1 which closes the gate H to pulses from G and a pulse over f2 to operate a circuit Z producing a pulse over output terminal z 1  which displays on banks K 1 , K 2  of glowdischarge tubes the units and tens settings of the counters N 1 , N 2  and therefore the percentage length of the received element. At the end of a short interval the circuit Z returns to its normal state and a pulse z 2  restores the counters N 1 , N 2  to their zero conditions. The distortion of negative pulses may be determined by moving the switch A to its lower position. If the pulse frequency of the generator G is not related precisely with the signal element frequency, the switch B is moved to the position shown and the gate H permanently opened so that the differentiated pulse at the end of a positive element passes a pulse over outlet z 1  to indicate the distortion on K 1 , K 2 . If the value of the indicated distortion varies continuously upwardly or downwardly the frequency of the generator G can be adjusted to show on K 1 , K an approximately constant indication for th distortion. Detailed circuit arrangement, Fig. 2.-With the switch A in the upper position to measure the distortion of positive signal pulses, a positive pulse at the beginning of the signal element renders the left-hand (1.h.) section of the double triode E 1  conducting so that the r.h. side is cut off and a positive voltage from resistor R 6  makes valve E 2  conducting so that a positive voltage is applied to the screened grid of valve E 3  to allow pulses from the generator G to be amplified and pass to the dekatron De 1  which initially has a discharge on its cathode " 0." After ten pulses applied to De 1  the discharge is stepped to the cathode " 0 " and the valve E 4  is rendered conducting to pass a pulse to the dekatron De 2  to step the discharge from cathode " 0 " initially to cathode " 1." The pulses from generator G step the dekatrons De 1 , De 2  until at the end of the positive signal element a positive pulse is applied from the transformer Tr 1  to the r.h. side of the triode E 1  which through resistor R 6  and valve Eg cuts off the valve E 3  so that the pulses from the generator G cannot reach the dekatrons De 1 , De 2 . Also, the 1.h. side of the valve E 1  is made non-conducting so that a positive pulse from resistor R5 makes the 1.h. section of a double triode E 5  conducting and valve E 6  conductive to illuminate for each of the groups D 1  . . . D 10  and D 11  . . . D 20  the glow discharge lamp associated with the respective glowing cathode of the two dekatrons De 1 , De 2 . After a short interval determined by the element combination C 1  and R 10 , the valve E 5  reverts to its normal condition with its r.h. side conducting so that a positive pulse renders a valve E 7  conducting to apply negative pulses through rectifiers U 1 , U 2  to set the dekatrons De 1 , De 2  to their normal or initial condition with the glow on cathodes " 0." With the contact members B 1 , B 2  of the switch B moved to the positions opposite to those shown, a positive potential is continuously applied over member B 1  to valve E 2  so that valve E 3  permanently passes the pulses from the generator G. The opened contact member B 2  prevents the application of resetting pulses to the dekatrons De 1 , De 2 .