US1958167A - Blocking arrangement in electric signaling systems - Google Patents

Blocking arrangement in electric signaling systems Download PDF

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Publication number
US1958167A
US1958167A US351027A US35102729A US1958167A US 1958167 A US1958167 A US 1958167A US 351027 A US351027 A US 351027A US 35102729 A US35102729 A US 35102729A US 1958167 A US1958167 A US 1958167A
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United States
Prior art keywords
circuit
line
currents
short
discharge
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Expired - Lifetime
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US351027A
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English (en)
Inventor
Laurent Torbern
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Telefonaktiebolaget LM Ericsson AB
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Telefonaktiebolaget LM Ericsson AB
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other

Definitions

  • the present invention relates to blocking arrangements in electric signaling systems including two circuits one of which is adapted to be made inoperative upon the second circuit being passed by current.
  • Such systems are used by way of example in long distance, l-wire telephone lines in which speech currents in the one transmission direction have to block disturbing currents such as echo-currents or the like in the other direction.
  • amplifying repeater sets it is also known to replace the electromagnetic relay by one of the valves in a repeater set the grid of said valve being subjected to a negative potential upon the second line being passed by current, whereby the anode circuit is blocked.
  • the blocking device is, however, comparatively slow-acting and, as regards the latter arrangement, it also produces a disturbing noise in the moment of blocking in the first line.
  • the object of the present invention is to eliminate said inconveniences and to bring about a blocking device operating practically instantly and without disturbing currents neither in the blocking circuit nor in the blocked circuit.
  • the invention consists substantially therein that one or more discharge devices such as glow lamps or the like are connected into the former circuit in such a manner as to form a short circuit upon being made operative by currents in the second circuit.
  • Figure 3 shows the circuit diagram of a detector device indicated D in Figures 1 and 2.
  • I denotes the line which is passed by the blocking currents whereas II indicates the line to be blocked.
  • the blocking device S comprising the detector device D is 4 connected into circuit.
  • the line I transmits, by way of example, speech currents an alternating potential is supplied to the terminals (11 and c2 of the detector device D which potential generates a continuous potential between the output terminals 111 and m of the detector device of such an amplitude that the two series connected discharge devices G1 and G2, by way of example glow lamps, start discharging.
  • Said glow-lamps or the like then form a direct current path over the two parallel connected lamps and short-circuit the line II between the points 011 and (12 thus making the line II inoperative.
  • Two condensers C1 and C2 are connected in series with the glowlamps so as to block direct currents passing through the lamps during operation.
  • the resistance in the short-circuit must be comparatively small in relation to the characteristic impedance of the line and this is brought about by a transforma- 5 tion to a higher value of the line characteristic counted at the point of the short-circuit.
  • Such a transformation to a higher value is brought about according to the embodiment in Figure l by means of two transformers T1 and T2 0 which have a low impedance in the windings connected to the signal circuit but a high impedance in the windings connected to the glow-lamps.
  • the shunt circuit including the glow-lamps G1 and G3 connected in parallel in relation to each other and in series with the condensers C1 and C2 respectively, brings thus about an efiicient shortcircuit between the points d1 and d2 of the curr nts in the line II.
  • the two transformers T1 and T2 effect the currents in the line II the transmission qualities of which line should be normal.
  • the transformation to a higher value of the characteristic is realized over a branch line connected to the line II.
  • the shortcircuit takes place over the two glow-lamps G1 and G2 connected in parallel in relation to each other and in series with the condensers C1 and C2 and over the choke coil L the eifective resis- 7 tance of which is equal to approximately 4 of the ohmic resistance of the winding provided the transformer is suitably designed with small magnetic leakage.
  • the purpose of the choke coil L in the embodiment according to Figure 2 which coil just as well may be included in the embodiment according to Figure 1 is to shorten the time required for completing the short-circuiting.
  • the short-circuit is namely not delayed in this case by the charging time of the condensers C1 and C2.
  • FIG 3 shows a circuit diagram of an embodiment of the detector device D.
  • the amplifying tubes F3 and F4 are supplied with a negative grid potential from the batteries V3 and V; respectively of such an amplitude that the anode current is practically equal to zero.
  • the batteries E3 and E4 have a voltage falling below the ignition voltage of the glow-lamps G3 and G4 respectively said glow-lamps being thus unable to start glowing in the inoperative condition of the blocking device and functioning as interruptions.
  • the transformer T3 superimposes alternating potentials upon the continuous voltage of the battery E3 which when reaching a certain predetermined amplitude start a discharge through the glow-lamp G3.
  • the upper coating of the condensers C3 or C4 respectively is charged positively which results in a displacement of the potential of the grids connected to said condenser coatings, in positive direction.
  • the condensers C3 and C4 will discharge with a certain sluggishness through the leak resistances R3 and R4.
  • the device functions as follows. Alternating currents enter from the line I to the terminals a1 and a2. They pass first the transformer T3 which is dimensioned so as to have its optional working within the range of voice frequencies which involves that currents of a comparatively low frequency such as disturbing currents from a power transmission line or noises or the like are shortcircuited over the primary coil of the transformer. Provided the oscillations within said range attain the required amplitude the glowlamp G3 starts glowing which results in a displacement of the potential of the grids connected to the glow-lamp in positive direction.
  • the leak resistance R3 is so dimensioned that the discharge through said resistance takes place with such a sluggishness that the grid voltage will vary with the modulating frequencies present in the incoming currents of voice frequencies but not with the voice frequencies themselves.
  • a low frequency current is obtained corresponding to said modulating frequencies.
  • the transformer T4 is di mensioned so as to operate within said range of low frequencies and transforms then the oscillations to the next valve circuit. If exceeding the predetermined amplitude the oscillations put the glow-lamp G4 into glowing and displace the potential of the grid of the tube F4 in positive direction.
  • the leak resistance R4 is so dimensioned that the discharge through said resistance takes place with a sluggishness sufficient to damp the oscillations of modulating frequency the grid thus obtaining a comparatively constant voltage.
  • a direct current voltage is obtained between the terminals 121 and 121 said voltage being maintained with a certain desired sluggishness which is determined by the sizes of the condenser C4 and the leak resistance R4.
  • said direct current voltage exceeds a certain predetermined amplitude the glow-lamps start glowing and the short-circuit of the line II is established.
  • the block ing arrangement starts operation when the speech currents search a certain predetermined amplitude, the device otherwise remaining inoperative.
  • Said predetermined value must, of course, be selected so high that the blocking device does not respond even to disturbing currents of maximum amplitude.
  • detector device With the described detector device an instantaneous blocking effect is further assured. If solving the problem to select the speech currents by means of filter devices or the like a longer I blocking time is required on account of inertia at the building-up process of the oscillations.
  • detector devices responding only to modulated voice frequencies may be arranged in several different manners.
  • An arrangement in electric signaling systems comprising in combination two transmission lines, a normally interrupted discharge device capable of independent discharge connected across one of said lines, and means under the control of the circuit of the other line for causing discharge in said discharge device upon transmission of oscillations over the line last mentioned so as to short-circuit the line first mentioned by means of said discharge device.
  • An arrangement in electric signaling systems comprising in combination two transmission lines, a normally inoperative neon tube device connected across one of said lines, and means under the control of the circuit of the other line for causing discharge in said neon tube device upon transmission of oscillations over the line last mentioned, so as to short-circuit the line first mentioned by means of said neon tube device.
  • An arrangement in electric signaling systems comprising in combination two transmission lines, a normally interrupted discharge device capable of independent discharge connected across one of said lines, and means comprising a rectifying device and arranged under the control of the circuit of the other line for causing continuous discharge in said discharge device upon transmission of oscillations over the line last mentioned so as to short-circuit the line first menside to one of said lines, two discharge devices connected in series to the output side of said rectifying device, means, comprising two condensers, for connecting said discharge devices in parallel across the other line, and means under control of the circuit of the first line for causing practically generates direct current as a result of the incoming oscillations.
  • a two-way repeater a pair of paths for repeating signals in opposite directions, means for disabling one of said paths in response to signals transmitted through the other of said paths, said means including a neon tube connected in said first signal repeating path, and means Whereby the signals in said second signal repeating path control the impedance of said tube.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US351027A 1928-03-31 1929-03-29 Blocking arrangement in electric signaling systems Expired - Lifetime US1958167A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE308816X 1928-03-31

Publications (1)

Publication Number Publication Date
US1958167A true US1958167A (en) 1934-05-08

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ID=20307588

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US351027A Expired - Lifetime US1958167A (en) 1928-03-31 1929-03-29 Blocking arrangement in electric signaling systems

Country Status (7)

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US (1) US1958167A (pt)
AT (1) AT116983B (pt)
BE (1) BE359396A (pt)
DE (2) DE495106C (pt)
FR (1) FR672141A (pt)
GB (1) GB308816A (pt)
NL (1) NL30423C (pt)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE755785C (de) * 1933-03-16 1952-03-31 Marconi Wireless Telegraph Co Anordnung zur automatischen Einschaltung eines Senders mit Hilfe von gleichgerichteten Modulationsschwingungen

Also Published As

Publication number Publication date
NL30423C (pt)
BE359396A (pt) 1929-04-30
AT116983B (de) 1930-03-25
FR672141A (fr) 1929-12-23
GB308816A (en) 1930-06-12
DE593628C (de) 1934-03-02
DE495106C (de) 1930-04-03

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