US1977965A - Communication system - Google Patents

Description

Oct. 23, 1934. D. JOURNEAUX COMMUNICATION SYSTEM Filed Sept. 10, 1952 mm 1 R W mm a xk D 04 Patented Oct. 23, 1934 PATENT orFicE 1,977,965 COMMUNICATION SYSTEM Didier Journeaux, Wauwatosa, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application September 10, 1932, Serial No. 632,577

9 Claims.

, This invention relates to communication systems and more particularly to systems in which the voice or signal level is raised by the use of amplifying means. a

In communication systems in which a telephone line extends adjacent a power line, disturbing currents may be induced in the telephone line from the power line by electrostatic v or by electromagnetic induction. The disturbing 10 action of such currents may be overcome by amplifying the voice currents at the transmitting station to an intensity greater than that of the disturbing currents, such voice currents then being reduced to normal level at the receiving station by suitable means which also reduce the disturbing currents to a value'suchthat their action no longer interferes with'the proper understanding of speech. Generally, the amplifier will be energized from the power line so that, when -such line becomes deenergized for any reason such as the occurrence of a disturbance therein, the amplifier will become inoperative. Under such conditions, the telephone line will no longer be influenced by the power line, so that it becomes possible to establish direct connection between the telephone and the power lines without interposition of the then inoperative amplifier thereby permitting normal operation of the communication system. Such result is particularly important when the communication line is used for controlling the operation of apparatus connected with the power line or for transmitting verbal orders between stations controlling such line. The telephone is automatically reconnected by means of a switch responsive to the voltage conditions in the power line.

It is, therefore, one object of the present invention to provide a communication system in which signals or voice currents are amplifiedto 40 a value higher than that of disturbing currents induced therein.

Another object of the present invention is to provide a communication system in which signals or voice currents are amplified at the sending station and reduced at the receiving station.

Another object of the'present invention is to provide a communication system in which signals or voice currents are amplified by means of amplifiers energized from a supply line inducing 5 interfering currents in the communication line.

Another object .of the present inventionis to (Cl. 179-78) l interfering currents in the communication line.

Another object of the present invention is to provide a communication system comprising a communication line in which signals or voice currents are automatically amplified upon energization of a supply line inducing disturbing currents in the communication line.

Objects and advantages other than those above set forth will be apparent from the description when read in connection with the drawing, which diagrammatically illustrates one embodiment of the present invention in which a plurality of telephone stations are connected by a line and receive current for power purposes from a come mon supply line.

Referring more particularly to the drawing by characters of reference, reference numeral idesignates a telephone line providing communication between a plurality of telephone stations of which only two are illustrated and aredesignated by A and B. Numeral 2 designates an alternating current power line from which power may be obtained at each telephone station through transformers 3. When line 2 is energized, it is assumed that such line induces disturbing currents in line 1 due to the particular construction and to the close proximity of the two lines which results in mutual electrostatic or electromagnetic induction therebetween. Induction of such currents in line 1 may occur along the entire length of line 2 or only along certain portions thereof, the remaining portions being either remote from line 1 or being so constructed as to avoid mutual induction therewith. The currents induced in line 1 by line 2 are assumed to be of such magnitude as to render speech transmitted over line 1 difficult to understand or even entirely unintelligible.

Each station such as A, B comprises a telephone, generally represented by 4 used in connection with an amplifier 6 with which it may be connected by means of aswitch 7. Each telephone 4 may be of any type known in the art, but the component parts thereof must be so connected as to make such telephone operable in conjunction with the remaining elements of the present system. Each telephone comprises a hand operated magneto 8 for the purpose of calling any of the other stations. Magneto 8 is connected with one conductor of the line through a switch 11 actuated by the switch hook 12 which is actuated by the earpiece or receiver and is generally in open circuit. When the crank of the magneto is turned, it closes the circuit of the magnet as is well known in the art, to connect such magneto across the two conductors of the line. A polarized bell 9 is connected across the line through switch 11 for converting ringing currents into audible signals. A transmitter or mouthpiece 13 is connected in series with a battery 14 and the primary winding 16 of a transformer or induction coil having a secondary winding 17, the circuit being closed through contacts of switch 11. The purpose of transformer 16, 1'7 is to amplify the voice currents to normal transmission level and to avoid transmission of the direct current supplied by battery 14 over the line. A receiver or earpiece 18 may be connected in series with winding 1'7 or may be connected in series with secondary winding 19 of a second transformer having its primary winding 21 connected across a portion of a resistance 22. Resistance 22 is connected across the line through switches 11 and '7 and is used as a potentiometer for supplying receiver 18.

Switch '7 comprises a plurality of contacts actuated by a cam 23 which may be operated by hand or by means of a solenoid 24 energized from transformer 3 through switch 37 and through a hand switch 26. The position of switch 7 may thus be controlled by hand or may be controlled in response to the voltage conditions in line 2. Amplifier 6 may be of any construction known in the art and is shown as comprising a single amplifying tube 27 connected with the telephone through a condenser 28 to prevent the fiow of direct current from tube 2'7 to the line. The amplifier is energized from a supply transformer 29 supplying a rectifying tube 31 connected through suitable filters 32 to apply a substantially uniform direct current to a voltage divider 33. The positive terminal of voltage divider 33 is connected with the plate of tube 27 through a choke coil 30. The input circuit of the amplifier is connected with the grid of tube 2'7 andwith the negative terminal of voltage divider 33, the output circuit being connected with condenser 28 and with the negative terminal of voltage divider 33 which constitutes a common point for both input and output circuits. Transformer 29 is energized from line 2 through transformer 3 and is connected therewith through the contacts 34 of a relay 36, such relay being energized only when line 2 is energized and contacts 37 are closed.

The system is shown so connected that the amplifiers are energized and connected with the telephones, the telephone receivers being off their hooks to permit the transmission of speech, such connections being shown to illustrate the functioning of the system. It will easily be understood that, when the system is not in operation, the receivers 18 are hung on hooks 12 so that switches 11 are reversed and switches 3'? are open, thereby deenergizing relays 36 which open their contacts 34 and deenergize amplifiers 6. The system being in the deenergized condition described, assuming that it is desired to call station B from station A, the operator of station A will operate magneto 8 which connects itself across line 1 through switch 11 to send ringing currents through the line. Such currents will thus circulate in station A from line 1 through magneto 8, switch 11, and back to the line, over the line to the other stations of the system where they will circulate through bells 9 and switches 11. Current also circulates in station A through hell 9 which is connected directly across magneto 8. It will be assumed that the ringing currents sent over the line were spaced at such intervals as to constitute a code indicating that communication is desired with the operator of station B only. Upon completion of the code signal, the operators in both station A and B lift their receivers 18 oiT switch hooks 12 thereby closing switches 3'7. Switches 37 being closed, solenoids 24 and relays 36 will be energized thereby bringing switches '7 into the position shown in the drawing and energizing amplifiers 6 to amplify the voice currents. Assuming first that speech is transmitted from station A to station B, lifting of receiver 18 from switch hook 12 reverses switch 11, thereby closing the circuit of transmitter 13. A current will then flow from battery l l through switch 11, winding 16 and transmitter 13, such current being modulated due to the impulses of speech waves in transmitter 13. By electromagnetic induction, currents are induced in winding 1'7 and will circulate in station A from the negative terminal of voltage divider 33, through switch '7, winding 17, switch 7 to the grid of tube 27. The voltage impressed thereby on grid of tube 2'7 is amplified, and the amplified speech currents will circulate in station A from line 1, through switch 11, switch 7,

condenser 28, tube 27, voltage divider 33 back to line 1. Such currents are then transmitted over line 1 to the other stations, but do not fiow to a material extent through stations other than A and B, in which only bell 9 is connected to the line, such bell presenting a high impedance to speech currents. Such voice currents, therefore, largely flow through station B, through a circuit from line 1, through resistance 22, switch 7, switch 11, back to line 1.

The above circuit also receives disturbing currents induced in line 1 from line 2. The voltage across a portion or" resistance 22 is impressed on winding 21 and a voltage is induced in winding 19 so that a current flows through winding 19 to receiver 18 over switch '7. The voice currents transmitted over line 1, having been amplified, must now be reduced to normal level by means of resistance 22 and transformer 19, 21 which reduce the interfering currents induced in line 1 by line 2 to a level such that they no longer interfere with the proper understanding of speech. A portion of the speech current is also received through a circuit of station A similar to the circuit of station B, so that the operator of station A hears his own voice at normal level and the interfering noises are reduced to a very low or to an imperceptible level. It will be under stood that if station B calls station A the process of operation will be similar but in a reverse direction because the two stations are identical in construction.

Assuming that line 2 becomes deenergized upon occurrence of a disturbance therein or for any otherreason, amplifiers 6 will become deenergized and will be incapable of transmitting speech currents from their input circuits to their output circuits. Solenoids 24 are also deenergized, thereby reversing switches '7 which connect the talking circuits of telephones 4 directly to line 1, but do not interfere with the connections of the ringing circuits. Under such condi tions, assuming that it is again desired to call station B from station A, ringing currents are sent over the line by the same process and over the same circuits previously described. Upon removal of receivers 18 from switch hooks 12, transmitter 13 in station A is again energized from battery 14 and a current modulated at voice frequency flows through winding 16. Voice currents at normal transmission level are then induced in winding 17 and flow in station A from line 1 over switch 11, switch 7, winding 17, two contacts of switch 7, receiver 18, back to line 1. Such currents are transmitted over the line to station B wherein they circulate in a circuit similar to that described for stationA. The. voice currents are thereby made". audible inreceivers 13 in both stations. It will ,beunderstood that the transmission of speech will be efiectedin an identical manner from station B back to station A. i x

It may happen that, due to some inherent defect or due to accidental causes, one of the amplifiers becomes inoperative, whereupon the station including such amplifier will still be capable of receiving speech, but not of transmitting speech. To permit two-way. communication even under such conditions, the amplifier in both stations may then be disconnected by reversing cams 23 manually or by deenergizing solenoids 24 by means of switches 26, thereby reversing switches '7 and connecting telephones 4 directly to the line. between the two stations is then possible to the extent permitted by the disturbing action of currents induced from the line 2. 1 r

It may also happen. that only a portion of line 2, connected withv station E for instance, induces disturbing currents in line 1 so-that,'in the event of such portionbeing deenergized, only the amplifier in station A will remain operative, but disturbing currents will no longer be induced in line 1. The operators in both stations A and B may then open switches 26 thus obtaining direct connection between the telephones and the line and transmission of speech without use of amplifiers.

A similar condition prevails if the amplifier in one station, such as stationA, is energized from a source of supply independent of line 2. Upon deenergization of line 2, the operator in station A must then open switch 26 to reverse switch '7 and connect telephone 4 directly to the line, the telephone in station B having been connected directly to the line because of deenergization of solenoid 24 upon the deenergization of line 2.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a communication system, a plurality of stations each having transmitting and receiving apparatus, an electric line connecting said stations, a source of electric current, means arranged in each of said stations for connection with the apparatus in said stations and with said source for amplifying the communication currents originating within said stations, and means for automatically connecting and disconnecting the first said means from the transmitting apparatus within said stations responsive to the voltage conditions of said source.

2. In a communication system, a plurality of stations each having transmitting and receiving apparatus, an electric line connecting said stations, a source of electric current, means arranged in each of said stations for connection with the apparatus in said stations and with said source for amplifying the communication currents'origi- Two-way communication nating within said stations, a switch connected with'each of said means, a switch controlling the receiving apparatus in each of said stations, said switches cooperating to manually control the connection of the transmitting apparatus of each of saidstationslwithsaid amplifying means associated therewith, and solenoids severally controlling the connection of each of said means with the transmitting apparatus of. each of said stations in response to the conditions of said source.

3. In a communication system, a power line arrangedladjacent the system, a plurality of stations each having communication transmitting and receiving apparatus therein, an electrically conductive line connecting said stations and subject to interference from said power line, means in each of said stations and energized from said ofsaid switches and responsive to energization of said power line to control connection of the first said means therewith.

la-In a communication system, a power line arranged adjacent the system, a plurality of stations each'having. communication transmitting and reoeivingapparatus therein, an electrically conductive line connecting said stations and subject to interference" from said power line, means in each of said stations and energized from said power line for amplifying the communication currents originating within said stations, and means responsive to the voltage of said power line to connect the transmitting apparatus with said connecting line directly when said power line is deenergized and through said amplifying means when said power line is energized.

5. In a communication system, a power line arranged adjacent the system, a plurality of stations each having transmitting and receiving apparatus therein, an electrically conductive line connecting said stations and subject to interference from said power line, means in each of said stations and energized from said power line for amplifying the communication currents originating within said stations, means to connect the transmitting apparatus with said connecting line directly when the power line is deenergized and through said amplifying means when said power line is energized, means for connecting said amplifying means with the power line when the power line is energized, and means responsive to the voltage of said power line to control operation of the last two said means.

6. In a communication system, a power line extending adjacent the system, a plurality of stations each having transmitting and receiving apparatus therein, an electrically conductive line connecting said stations and subject to interference from said power line, means in each of said stations and energized from said power line for amplifying the communication currents originating within said stations, means responsive to the voltage of said power line to connect the transmitting apparatus in said stations with said connecting line directly when said power line is deenergized and through said amplifying means when said power line is energized, means for connecting said amplifying means with said power line when said power line is energized, and a switch controlling the receiving apparatus whereby the last two said means are controlled.

7. In a communication system, a power line extending adjacent the system, a plurality of stations each having transmitting and receiving apparatus therein, an electrically conductive line connecting said stations and subject to interference from said power line, means in each of said stations and energized from said power line for amplifying the communication currents originating within said stations, means for reducing the intensity of the amplified communication currents to the normal level of audibility, and means responsive to the voltage of said power line to connect the transmitting and the receiving apparatus directly with said station connecting line when the power line is deenergized and to connect the transmitting apparatus with said station connecting line through said amplifying means and to connect the receiving apparatus with said station connecting line through thesecend said means when said power line is energized.

8. In a communication system, a power line extending adjacent the system, a plurality of stations each having transmitting and receiving apparatus therein, an electrically conductive line connecting said stations and subject to interference therefrom, means in each of said stations and energized from said power line for amplifying the communication currents originating within said stations, means for reducing theintensity of the amplified communication currents to the normal level of audibility,- means-responsive to the voltage of said power line to connect the transmitting and the receiving apparatusidirectly with said station connecting line when said power line is deenergized and to connect the transmitting apparatus with said station connecting line through said amplifying means and to connect the receiving apparatus with said station connecting line throughvthe second said means when said power lineis energized, and means for connecting said amplifying means with said power line when said power line is energized.

9. In a communication system, a power line extending adjacent the system, a plurality of stations each having transmitting and receiving apparatus therein, an electrically conductive line connecting said stations and subject to interference from said power line, means in each of said stations and energized from said power line for amplifying the communication currents originating'within said stations, means for reducing the intensity of the amplified communication currents to the normal level of audibility, means responsive to the voltage of said power line to connect the transmitting and the receiving apparatus in said stations directly with said station connecting line when said power line is deene'rgized and to connect the transmitting apparatus with said station connecting line through said amplifying means and to connect the receiving apparatus with said station connecting line through the second said means when said power line is energized, and a switch controlling the receiving apparatus in said stations whereby the last two said means are controlled.

DIDIER J OURNEAUX.

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