US2153040A - Signal transmission system - Google Patents
Signal transmission system Download PDFInfo
- Publication number
- US2153040A US2153040A US182442A US18244237A US2153040A US 2153040 A US2153040 A US 2153040A US 182442 A US182442 A US 182442A US 18244237 A US18244237 A US 18244237A US 2153040 A US2153040 A US 2153040A
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- US
- United States
- Prior art keywords
- circuit
- relay
- switching
- switching circuit
- path
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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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
- This invention relates to two-way signal transmission systems and particularly to signalcontrolled switching circuits for directionally controlling transmission in such systems while preventing singing and suppressing echoes.
- Such switching apparatus usually comprises means for diverting from the one-way path transmitting signals, a portion of the signaling energy, means for amplifying and detecting that energy, and then utilizing the detected energy to operate relays or other switching apparatus to apply short circuits to the circuits to be controlled, or to properly control the switching of loss pads or the operation characteristics of transmission apparatus in the controlled circuits.
- each switching circuit in response to appliedsignals, cause complete or partial disabling of the other switching circuit by applying the proper bias to the screen grid of a detector tube in the latter circuit.
- These two circuits may be, for example, part of a two-way telephone repeater, or a fourwire telephone circuit, in which case they would be connected at their terminals to two-way line sections by the usual hybrid coils and associated balancing networks, or other suitable means, so that the one-Way circuits are connected in transmitting relation with the line sections but in conjugate relation with each other.
- a switching circuit 3 comprising the one-way amplifying device 4, the detector 5, and a chain of switching relays including the polarized relay 6 and the polarized relay i, controlled by operation of the detector 5.
- the switching circuit 8 connected across the circuit WA in front of the amplifying device 2 is the input of the switching circuit 8 comprising the one-way amplifying device 9, the detector I and a chain of switching relays including the polarized relay I I and the polarized relay I2 controlled by operation of the detector III.
- the detector in switching circuit 3 comprises a single electron discharge tube of the pentode type having a cathode I3, which may be of the heater type supplied with heating current in any suitable manner, the anode I4, and spaced between the cathode and anode a control grid I5, a screen grid I6 and a suppressor grid I! which is connected directly to the cathode.
- the control grid-cathode circuit of tube 5 is coupled to the output of the amplifying device 4 through resistance I8, and the tube 5 is normally biased to cut-off by a negative potential applied to the control grid I5 from the grid battery I9 through the resistance I8.
- Plate current is supplied to the anode I4 of detector tube 5 from plate battery 2!] through the biasing winding 2
- the detector III of the switching circuit 8 connected to the one-way circuit WA comprises a single electron discharge device of the pentode type having a cathode 24, an anode 25, and spaced between the cathode and anode a control grid25, a screen grid2'l and a suppressor grid 28.
- the control grid-cathode circuit of tube I0 is coupled to the output of the amplifying device 9 through resistance 29, and the tube I 0 is normally biased to cut-off by the negative potential on control grid 26 applied by the grid biasing battery 30 through resistance 29.
- Plate current is supplied to the anode 25 of detector tube I from plate battery 3
- the screen grid l6 of the east detector tube 5 is normally positively biased by plate battery 20 through winding 35 of polarized relay I2 and resistance 36 in series.
- the screen grid 21 of the west detector tube I0 is normally positively biased by plate battery 3
- the armature of the polarized relay 6 is normally held on its contact 39 by current flowing from the plate battery 3
- the armature of polarized relay 1 is held on its contact 43 by current flowing from the battery 44 through the biasing winding 45 to ground so that the resistance 46 is shunted across the circuit EA in the output of amplifying device I, through the armature of relay 1.
- the value of resistance 46 may be chosen, for example, so that it provides a normal loss of about 5 decibels in the circuit EA.
- the armature of polarized relay II is normally held on its contact 41 by current from the plate battery 20 flowing through the biasing winding 2
- the armature of polarized relay I2 is normally held on its contact 5
- the value of resistance 54 may also be chosen so that it provides a normal loss of about 5 decibels in the circuit WA.
- the speech currents diverted into the circuit 3 will be amplified by amplifier 4 therein, and the amplified waves impressed upon the control grid-cathode circuit, of detector tube 5 across resistance l8.
- the impressed speech voltages will overcome the normal negative bias on the control grid of detector tube 5, so that current will begin to flow in its anode-cathode circuit.
- the alternating current component of this current will be shunted through condenser 23 and the direct current component will flow in series through the biasing winding 2
- the amount of current flowing through the winding 22 will be sunlcient to cause operation of that relay to shift its armature from contact 39 to contact 55.
- a previous desensitization of switching circuit 8 occurs when direct current first flows in the anode-cathode circuit of detector tube 5 in switching circuit 3 in response to wests speech currents from the circuit EA, since the biasing winding 2
- This additional loss is particularly desirable to prevent false operation in systems requiringthe use of very sensitive amplifier-detector switching circuits, such as, for example, the voice-operated loss control and anti-singing circuits (Volcas) used with two-way repeaters in multi-repeatere-d two-wire telephone circuits or in multi-way or conference interconnecting telephone circuits, as disclosed in Fracassi Patent 2,083,645, issued June 15, 1937.
- Volcas voice-operated loss control and anti-singing circuits
- the disabling of the detector tube instead of the amplifier tube in the switching circuit is advantageous in that the former does not result in the transmission of surges of current obtained in the latter case which would tend to act to produce false operation of the associated switching relays.
- the transmission circuit EA will remain operative, the transmission circuit WA will remain blocked to suppress echoes and prevent singing, and the switching circuit 8 will remain disabled to prevent false operation by subsequently received speech currents from the east subscriber, as long as the west subscriber continues to talk.
- the west subscriber ceases talking or pauses for a sufiicient interval of time so that the amount of speech energy impressed on the control grid-cathode circuit of detector falls below the cut-off value of that tube, detector tube 5 will immediately be rendered inoperative.
- the breaking of contact 55 of polarized relay 6 breaks the connection of battery 3
- This fiow of current through winding 37 will hold the polarized relay 1 operated for a desired hangover time interval after the polarized relay 6 has released, so as to prevent the unblocking of the circuit WA and the switching circuit 8 until all echoes due to wests speech currents have been dissipated in the circuit EA.
- the circuit can be arranged so that the detector tube 10 is returned to practically full sensitivity at the same time that polarized relay 1 releases. At the end of this time interval all of the relay and other circuits will have returned to the normal condition indicated in the drawing, and the switching circuits are in condition to be exclusively controlled by the west subscribers or the east subscribers speech currents, depending on which are first to arrive at the switching point.
- each of the one-way transmission circuits may be normally operative and adapted to be disabled under control of the switching circuit associated with the other one-way transmission circuit;"one transmission circuit may be normally operative and the other normally blocked and the former adapted to be blocked by operation of the switching circuit associated with the latter circuit, and the latter rendered operative under control of the switching circuit associated therewith; the blocking and unblocking of the one-way transmission circuits may be obtained by varying the bias on the grid of an amplifier tube in each circuit under control of the associated switching circuit; the switching circuit may be modified so that the disabling of each under control of the other switching circuit is obtained solely by varying the bias on the screen grid of the detector tube in the circuit as indicated, the short-circuiting of the input of the switching circuit being eliminated. It should also be understood that the specified values for the losses inserted in the transmission paths are given by way of example only, and that they may be quite diiferent
- a switching circuit connected to each path, including an electron discharge detector tube having a cathode, an anode, a control grid and a screen grid, and circuits therefor, said switching circuit being responsive to signal transmission in the path to which it is connected to insert attenuation in the other path, and to bias the screen grid of the detector tube in the switching circuit connected to said other path, so as to disable that tube and thus prevent subsequent false operation of said other switching circuit by transmission in said other path.
- a four-wire circuit comprising two oppositely directed oneway paths for the signals transmitted in opposite directions, a switching circuit including an electron discharge detector tube having a cathode, an anode, a control grid and a screen grid connected to each one-way path and responsive to signal transmission therein to switch loss out of that path and loss into the other path, and means also responsive to signal transmission in the first path to control the bias on the screen grid of the detector tube in the other switching circuit connected to said other one-way path, so as to prevent subsequent false operation of said other switching circuit in response to subsequent signal transmission in said other circuit.
- a four-wire circuit comprising .oppositely directed one-way amplifying paths for other path to suppress signal echoes, and to switch loss into the input of the other switching circuit connected to said other path, to reduce its sensitivity, and means to provide increased protection against ,false operation of said other switching circuit' by applied signals from said other path after the f rst switching circuit has started to operate, comprising means under control of the signals appliedto said first switching circuit to apply, a blocking bias to the electron discharge detector tube in said other switching circuit, through its screen grid.
- a control circuit including an electron discharge detector tube having a screen grid, connected to each path so as to be responsive to signal transmission in that path, a chain of relays responsive to the output current of the detector tube, when operated, to switch loss into the other signal transmission path to suppress signal echoes and to switch loss into the input of the other control circuit, and means responsive to the operationof the first relay in the chain in the first control circuit by the detected current to so con trol the bias on the screen grid of the detector tube in said other control circuit as to block that tube, and thus to prevent false operation of said other control circuit by transmission in said other path during the time interval required to produce complete operation of said first control circuit.
- a control circuit including anelectron discharge device having a cathode, an anode, a control grid and a screen grid, connected to each one-way path so as to be responsive to signal transmission in that path, in the absence of prior signal transmission in the other one-Way path, to switch loss into said other path to suppress signal echoes, and to switch loss into the input of the other control circuit to reduce its sensitivity, means to provide increased protection against false operation of said other control circuit by applied signals from said other path after the first control circuit has started to operate, comprising means under control of the signals applied to said first control circuit to apply a blocking bias to the electron discharge device in said other control circuit, through its screen grid, means for maintaining the loss in said other path and in the input of said other control circuit for a desired hangover time interval after cessation in the supply of controlling signals to said first control circuit, and means to return the electron discharge device in said other
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Amplifiers (AREA)
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US182442A US2153040A (en) | 1937-12-30 | 1937-12-30 | Signal transmission system |
| FR848213D FR848213A (fr) | 1937-12-30 | 1938-12-30 | Perfectionnements aux systèmes de télécommunications |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US182442A US2153040A (en) | 1937-12-30 | 1937-12-30 | Signal transmission system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2153040A true US2153040A (en) | 1939-04-04 |
Family
ID=22668507
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US182442A Expired - Lifetime US2153040A (en) | 1937-12-30 | 1937-12-30 | Signal transmission system |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US2153040A (fr) |
| FR (1) | FR848213A (fr) |
-
1937
- 1937-12-30 US US182442A patent/US2153040A/en not_active Expired - Lifetime
-
1938
- 1938-12-30 FR FR848213D patent/FR848213A/fr not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR848213A (fr) | 1939-10-25 |
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