US2623998A - Device for obtaining from a pulse another pulse of accurately predetermined duration - Google Patents

Description

2,623,998 M A PULSE} ANOTHER PULSE 112/!) GJLZ or Filed Feb. 20, 1950 G. G. EMANUELSSON E FOR OBTAINING FRO GF ACCURATELY PREDETERMINED DURATION DEVIC Dec. 30, 1952 Patented Dec. 30, 1952 a DEVICE FOR OBTAINING FROM A PUL SE ANOTHER PULSE OF ACCURATELY PRE- DETERMINED DURATION v Gunnar Gideon Emanuelsson, Stockholm, Sweden, assignor to Telelronaktiebolaget L' M Ericsson, Stockholm, Sweden, 2. Swedish com- Application February 20, 1950, Serial No. 145,161 4 In Sweden March 3, 1949 2 Claims. (Cl. 250-27) The present invention relates to a device for obtaining a pulse of accurately predetermined duration, which within some ranges of technics, for instance signal transmission with time modulated pulses in several transmitting channels, is an indispensable condition for obtaining a good transmission.

In order to solve the problem of obtaining a pulse of accurately predetermined duration, devices have earlier been proposed working with rectiflers or electron tubes as principal constituents. The principle for these devices is to amplify a narrow strip from a fed-in pulse, the base of which is of longer duration than the base or the rectangular pulse which is finally desired to have, said strip being parallel to the time axis and chosen at a suitable distance from the same. The flanks of the strip are comparatively steep, whereby a pulse having a nearly rectangular shape is obtained. This may for instance be done with a device containing an electron tube, the voltages and connection elements of which have been chosen so, that the tube is barred at grid bias voltages smaller than the voltage representing the lower limit of the above-mentioned strip and overloaded for grid voltages greater than the voltage representing th upper limit of the strip.

It is also known to let the original pulse produce two pulses, which have almost opposite sign, and to let each of said pulses influence a tube, these tubes lying in series in a circuit. On the output side of this circuit a pulse is obtained, the duration of which is a function of the deviation from opposite sign existing between the two pulses.

The present invention relates to a device, where a pulse with comparatively steep flanks and of a duration exceeding a certain value, may pass two difierent paths, of which one contains a time delaying device, to two electrodes in an electron tube device, whereby a pulse is obtained on the output side of the device, the duration of which pulse is a function of the difference of transittime, which the two pulse paths give rise to. On condition that the amplitude and the duration of the original pulse exceed certain minimum values neither the normally occurring fluctuations of the voltages connected to stages immediately before the device nor those of the tubes of the device will influence the duration of the received pulse.

The invention will be described more closely with reference to the accompanying drawing, in which Fig. 1 shows a circuit diagram to a device according to the invention, and Figs. 2, 3 and 4 show the voltage as a function oftime on grid, cathode and anode in a three-electrode valve working in said device.

In Fig. 1, l and 2 indicate the input terminals of the device, 3 is a blocking condenser for direct current, 4 is a delay network built up by coils and condensers, 5 a switching condenser and 6 a cathode resistance to the electron tube 1. 8 is a working resistance, 9 and Ill a voltage divider for obtaining a suitable grid voltage, II is a grid voltage battery, [2 an anode battery and I3 and i l at last are output terminals of the device.

The function of the device is as follows: when a pulse arrives at terminals l and 2, there are two possible paths, partly via the switching condenser 5 to the grid in the electron tube 1, partly via the delay network 4 to the cathode in the same electron tube. If the input pulse is rectangular, the voltage 6g of the grid will be a function of the time t as Fig. 2 indicates. The pulse is supposed to arrive at terminals l and 2 at the time 231; the voltage of the grid will then rise to 9g]. and remains at this value until the time its, when the input pulse ceases.

Accordingly, when the grid grows positive, the tube is current carrying, whereby the anode voltage drops thanks to resistance 8. The anode voltage as a function of time appears from Fig. 4; before the pulse arrives at terminals I and 2 the anode voltage is equal to the voltage 62.0 of the anode battery. At the time h the anode voltage drops to 62.]. due to the voltage drop arisen across the anode resistance 3. At the same time as the anode voltage is falling, the cathode voltage will rise because of the voltage drop across the cathode resistance 6. Fig. 3 shows the cathode voltage as a function of time. At the time 121 the cathode voltage rises to ekl and remains constant until the time tz when the pulse via the delay network d reaches the cathode. The cathode voltage rises to 6k2 which cause that the current through the tube will be equal to 0, i. e. the anode voltage regains the value 83.0. When the pulse via the delay network ceases at the time it, the cathode will obtain the same voltage as before the time 261, and the whole process is finished. A pulse is thus obtained across the output terminals [3 and [4, the duration of said pulse being dependent on the difierence of transit-time tz-tr, which the two paths via the delay network a and the condenser 5 give rise to.

I claim:

1. An electrical impulse converting system for obtaining from an original pulse an accurately predetermined pulse of short duration compristerminal being connected to a point in the 'cathode-anode circuit of the electron tube having a potential of a different value from the potential of the cathode of the electron tube.

2. An electrical impulse converting system'e'om prising an electrical delay ne'tworkhav'ing a fixed impedance and input and output terminals, an

electron tube having a cathode, grid, and an anode, one output terminal of the electrical delay network being connected to the cathode of the electron tube, a branch circuit including a blocking capacitor between one input terminal of the electrical delay network and the grid of'the electron tube, a voltage divider circuit including a resistor connected between the grid ofthe electron tube and the other output terminal of the eleotrical delay network, and a grid battery and a resistor connected between the said latter output terminal of the electrical delay network and the grid of the electron tube, an output circuit including a resistor connected in series with the anode of the electron tube, output terminals connected on the opposite sides of said latter resistor, and an anode battery connected between the latter output terminal of the electrical delay network and one of the latter output terminals.

GIDEON EMANUELSSON.

file of this patent:

UNITED STATES PATENTS Number Name 1 Date 20 2,252,599 Lewis Aug. 12, 1941 2,266,154 Blumlein 'Dec.*16j, 1941 2,437,313 Bed'ford fMar e, I948 2,564,824 White Aug. '21 1951

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