US1624672A - Communication system - Google Patents

Description

Apr1l 12, 1927. w. UNEILL- COMMUNICATION SYSTEM Filed Dec. 17, 1924 5 Sheet-She'et 1 lnrenfvn' Y Henry If. 0772/7! by Alf}! April 1927' H. w. O'NEILL COMMUNIGATION SYSTEM Filed Dec. 17, 1924 5 Sheets-Sheet 2 /nrehfor: flew/y I1. 4772/ 1927. April 12 H. w. O'NEILL cpmuNIcA'rIou SYSTEM M 3 I W. m RQ m 5 V in h 4 E 1 H H i m M Y 12 1921. 1624 672 n 7 w. ONEILL CUMMUNICATION SYSTEM Filed Dec. 17, 1924 Sheets-Sheet 4 www Mum \NM\ a e w m u M. v u U .R 3 S 3 Filed Dec. 17, 1924 5 Sha ts-Sheet 5 .3 NM \Nw 83 m lg x N Mk v a h. Q J 4. M a w x N \\M 4 (x s v 9 m QQQ Q N f Y. J, N svs g S M v 7 2w Patented Apr. 12, 1927.

UNITED if srarss HENRY ONEILL, OF ELMI-IURST, NEW YORK, ASSLGNOR TO WESTERN ELECTRIC YEICE...

COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

, COMMUNICATION SYSTEM.

Application filed December 17,1924. Serial No. ass r03.

This invention relatesto communication systems and more particularly to systems of radio-wire communlcatlon.

The object. of this invention is to provide a system whereby land lines or wire circuits may be joined to radio systems for the optional handling of either telephone or telegraph messages. v r

A feature of the invention is the employment of an improved system involving a plurality of switching equipments respectively located at separate points relative to radio transmitting and, receiving sets and arrangedin such a manner that the establishment and control of radio-wire connec-' tions may rest either with a single switchingpoint or the control may be divided between a plurality of such points, and further, that such joint control may be on either of several'difterent plans, as a parallel relation or aseries relation or a combie nation of paralleland series relations relative toth'e circuits of the switching facilities at the different points. a

. Another feature is the provision for reciprocal control of the call and supervisory signals relative to radi circuits or channels.

I Anotherfeature is the pIOVlSlOIl of an arrangement for the wire side of a connection whereby either two-wire orfour-wire working may .be'resorted to, while equipment.

automatically responsive to the handling of traffic may render receiving and sending devices of an attendants equipment effective with circuits ancillary to and differing from the main channelsof a connection.

Another feature is the provision of an arrangement whereby any switching point may serve either as a terminating station or as a repeater station relative to the handlin'g of communications over wire or radio channels or on mixed connections relative to wire and radio working or on wire-towire communications. 1 Another featureis the provision of improved meansv for supplying so-calledside tone relative to transmitter and receiver of a telephone set when these instruments may be respectively associated with electricallyv isolated circuits usually present in four-wire working.

Another feature. is the provision of an improved signaling arrangement whereby o channels and wire asingle visual signaling deviceis emploved both as a calling signal and as a clearingout signal. 7 v P Another feature isthe provision of a circuit arrangement wherein an. incoming line .is provided with a visual signal device at each of twof operators boards and means actuated when thecall is answered from one board for retiring both :signals, and

means for reoperating only the signal at the board Where the call is answered when the calling party disconnects.

Another feature is the provision of an arrangementwhereby the receiver, may be applied to either side of a four-wire circuit for communication purposes, the impedance ofthe circuit being increased when the re ceiver 1s employed for monitoring purposes Another feature is the provision, of a circult arrangement involving compensating means inthe operators; set which renders the voice currents impressed on the ampli- "fiers the operator of substantially the same intenslty as those which would be im-\ pressed from the transmitting end, that is, this resistance in effect, sets the operator back to the transmitting end and makes it unnecessary to adjust the gain device before and after the. operator calls.

improved system to prevent false signals Another feature is. the provision of an Another feature is the provision of a coin from the land lines from operating the calling signals. e

Another, feature is the] provision tea e11- cuit arrangement whereby low frequency oscillations are impressed on high frequency oscillations from either one of two points connected in. a directmirrent circuit.

Another feature is the provision oftwo alternating current relays in the signaling circuit tuned to respond to differentfrequencies, preferably within the voice range, and a signal operated only on the simultaneous response of both relays.

Another feature is the provision of a monitoring setincluding an induction coil having a high impedance prin'ia-ry winding connected across the cord being monitored,

an amplifier being connected to the secondary winding, whereby transmission is not impaired.

Another feature is the provision of an arrangement whereby the operator may modulate the carrier waves by voice currents or low frequency telegraph waves without changing the transmitting circuit, the circuits being so arranged that when the telegraph key is in the operated position, the talking transmitting circuit is In operative relation with the radio trammitter. I

Another feature is the provision of a cir-- cuit for eliminating the ringing key in the cord circuit and consists in providing a common relay associated with the signaling generator, and a relay in each line circuit, the common relay being actuated upon the operation of the generator, and the relay in the line taken for use being operated due to the conjoint actuation of the common relay and the talking key of the cord used. A related feature is the provision of a circuit arrangement for applying signaling current to the line over a path independent of the cord used and at a point beyond the terminating equipment of said line, said equipment being of a character opaque to such low frequency signaling currents.

Another feature is the provision of a circuit arrangement involving the application of a substantially zero resistance ground, to the high frequency currents used in radio transmission, to one of the strands of the cord circuits to prevent interference.

Another feature is the provision of a circuit arrangement for communicating systems using four-wire circuits, the receiver and transmitter being connected respectively to the two sides of the circuit for affording side tone without physically con necting the two sides of the four-wire circuit, consisting in providing means for directing a portion of the energy fromthe transmitter to the receiver without establishing a path whereby an appreciable amount of energy is transferred between the two sides of the four-wire circuit.

' Another feature relates to communicating ystems using four-wire circuits wherein two of the wires are used for transmitting and two for receiving, consisting in the provision of manually controlled switches for utilizing either of said pa'rs for local telephone conversations.

Other features of the invention will appear from the following description together with the appended drawings in which Fig. 1 shows the terminating equipment T, line L, equipment. OT of and in connec tion with an operators telephone set, a cord circuit C of the two wire type, Fig.

1 shows line circuits L1 and 11-2 four wire working which may be used in place of the two wire line L of Fig. 1.

Fig. 2 shows a four wire circuit C1, telephone signaling equipment, telegraph signaling equipment S1, and a system for measuring the strength of voice and telegraphic currents.

Fig. 3 shows equipment RT of a radio transmitting system with circuit facilities corresponding to a radio receiving system RR and a trunk and line equipment TL while equipments L-3, T1, OT-1, C2, S2, S3 and M-1 may be considered, respectively, as corresponding with equipments L, T, OT, C, S, 8-1 and M of Figs. 1 and 2.

Fig. 4 shows the radio equipment for a ship; while Fig. 5 shows the equipment for a second radio station with'the equipments of either Fi s. 1, 2 and 3 or other stations having equipment similar to the system of Fig. 1. In describing this system the equipments of Fig. 1 and Fig. 2 and that portion of equipment of the radio system to the left of line D (Fig. may be considered present at a radio wire station at which radio transmitting equipment HT is present while the equipment at the right side of line D may be considered as located at a radio wire receiving station- The line circuit L (Fig. 1) may be considered as extending to a distant toll or long distance telephone switchboard and through which connections may be estab lished with other land lines. This two wire circuit terminates in a repeating coil 1 of .the hybrid type having a secondary winding 2 joined to a jack 3 while thebridge points of the coil 1 are connected to an autotransformer l, which in turn is connected to a jack 5. The purpose of the auto transformer is to increase the impedance of the circuit from the bridge points of coil 1 to correspond with the impedance of the secondary or output winding 2. The artificial line 6 serves as a balancing network for the line L. The relay 10 is controlled from a cord circuit as will be presently described, and serves for disconnecting the hybrid coil and for a plying signaling current outward over the line circuit. During such operations, this relay also connects a resistance or network 111, corresponding to the network 6 to maintain a balanced condition at the hybrid coil, whereby the tra: sfor of energy between the radio transmitting system and the radio receiving system is prevented when the line is disconnected from the hybrid coil, during a ringing period. t 7

Called signals from the line L are received asfollows. Ringing current incoming from the line L flows through the relay for 15, which being energized, pulls up its armatrue to thereby open the circuit including the normally energized relay 16. The armature of relay 16 therefore falls off] and completes acircuit including grounded battery, the'windi'ng of relay 17 resistance 19 and relay 201 (Fig. 2) which is connected toground. The relay 17 being energized, actuates the two armatures associated with it.

The left hand armature opens thecircuit of 1 arately shown, keys 210-211 may be considered as units forming a single key, while units 215-216, 220221, 225 226 and 230-231 may be considered as similarly constituting single keys. The units 2102l1 serve as a so-called splitting key for disco'ne necting the left-hand end of the cord circuit, while units 215-216 form a key to disconnectthe right hand end or radio side of the cord circuit. Units 220-221 permit the operators telephone set to be connected for talking on .a circuit which may be used to establish a'connection between the line and radio equipment. Units 225226 form a key for monitoring and units 230--231 form a key whereby the operators transmitter and receiver may be reversed or transposed relative to the two sides of the four wire cord circuit. 7

At the splitting key unit 210, the trans,- former 217 may be connected to a radio rcceivingsyste'm. During the period of a connection this key may be operated for the purpose of including a'device M2 which corresponds with the current indicating systern M wherebyfwhen the radio side of a connection is disconnected, incoming voice orfsignaling current will be indicated in the system M-2. The resistance units or networks 212 and 213 will be connected to the respective sides of the four wire circuits connected to the line L when the key 210-211 is operated to disconnect the circuits in that direction. The purpose of these resistances is to maintain'a balanced condition relative to the terminating equipment T of the line 'L during suchperiods. The jacks 222 and 223 are provided to permitthe speech meter M to be connected by theplug 224 with either side of the four wire connection. Key units 2021 (Fig. 1 are also mechanically connected to form a single key which is used'to control the connection of the 1 transmission loss networks '25 and 26 with respect to the circuits at a point intermediate between an operators telephone receiver 23' .andthe transmitters'22 or 31 and the re-' from a transmissionstandpoint,

circuit 'L. Therefore, following the establishnient of aconnection with a distant radio station or ship, galn' controls227 and 228' of i.)

the cord circuit C1 may be set by the operator to determine a speech energi level which will be satisfactory when the connec tion is extended through or linked to the toll operator at the assumed distant point.

In establishing a connection betvveenline and the radio link, plug& 7- and 8' are -nserted in acks 3 and 5 of the toll line L while plugs 20Tand-208 are inserted in, jacks 303 and 305 of the equipment of Fig. 3. Incoming radiowaves incident upon the antenna 301 will be supplied to the radio receiving equipment ER in which theywill'be detected to reproduce speech currcnt.s The detected speech currents will traverse the main conductors of the trunk the main-members of jack 303 and plug 207, maincondujctors 203 and 204 of the cord circuit, main members of jack 7 and. plug 3 and the terminating equipment T of thetoll line L.

Speech currents from theline L will traverse the main contact members of jack 5 and plug 8, main conductors 205 .and 206 of the cord circuit, main contact members of plug 208 and jack 305, thence to the radio transmitting equipment RT. A. speech modulated radio frequency wave will be supplied to and radiated from the transmitting antenna302f 5 I During the'period of the connection just described, it may be desirable for the operator at the radio receiving station to be. able to talk, monitor, signal," etc. This'may be accomplished by associating a four-wire cord circuit C-2, including equipment simia lar to that of cord circuit C 1, With the radio transmitting and receiving apparatuses. The cord circuit C-2.may be connected either in parallel, in series, or in" series multiple with the cord circuit C1.

For a parallel connection of the receiving operators set OT-l, with the cord circuit C1; the plugs 307 and 309 of the cord circuit C--2 are inserted in the corresponding jacks 306 and 310.

,To provide for four wire working on the land line side of a cord connection, the plugs 7 and 8 of the cord circuit C1 should be inserted in jacks 13 and 14, Fig. 1, respectively, of the lines L 1 and L'2 which form a four wir-ecircuit. Equipment corre: sponding with signal receiving equipment, constituted by relays 15, 16 and 17 and Sig: nal 18 of the line L, is provided at RE on equipment similar to the signaling relay 10 and associated apparatus of line L.

The arrangement of a connection, where by the switching equipment at the first or transmitt'ng station maybe in series or tandem with the switching equipment at the second or receiving station, is accomplished by inserting the plugs 207 and 208 of cord circuit C-l in jacks 313 and 315 of trunk circuits 314 and 318, respectively. At the second station plugs four-wire cord circuit C-2 are inserted in jacks 316 and 317 of the trunk circuits 314 and 318, while the opposite plugs 307 and 309 are inserted in the jacks 310 and 306, respectively, of the trunk circuits 304 and 308 associated with the radio receiving and transmitting systems. 'Under such an assumed connection, the matter of setting the gain control devices rests with either station. At the station to which such operations may be assigned, a key 229 (Fig. 2) may be operated for connecting the gain control devices 22? and 228 in circuit with the two sides of the four wire cord circuit.

For a connection, which may be referred to as a series multiple combination, the plug 207 is inserted in jack 313 of the trunk 314 while plug 208 is inserted in jack 305 of trunk 308. At the other station, plug 320 of the cord circuit C2 is inserted into jack 316 of the trunk 314 and plug 307 is inserted into jack 310 of trunk 304. When this connection is made, incoming voice currents from line L will traverse the lower side of the cord circuit C1 and the connection of the trunk 308 to the radio transmitting antenna 302, while voice currents arriving over the receiving antenna 301 will traverse the upper conductors of the four-wire cord circuit C2, trunk 314, thence over the upper side of the cord circuit C1 to the line L. Thus speech currents resulting from detecting the incoming radio waves will be trans mitted in tandem through the cord circuits C2 and C1 to the toll line L, while currents from this line to the radio transmitting equipment will traverse only the circuits of the cord C1. The radio transmitting equipment however, will be accessible to the lower half or side of the cord circuit 02 at the second station, if desired, by inserting plug 309 into jack 306. of the trunk 308 connected to the radio transmitter.

In a converse manner, eq i-iipmcnt may be placed in series with one side of the cord circuits C1 and G2 at the respective stations, while the radio receiving circuits will be connected directly through the upper side of the cord circuit 01 to the li-neL. Bridged supervision on the incoming radio channel will be carried out during such periods at the second station by inserting plug 307 into jack 310 of the trunk 304.

Referring to the equipment of the operthe transmitting 320 and 321 of the ators telephone set (OT, Fig. 1) the telephone transmitter 22, which may be ofthe so-called switchboard type, will be energized by inserting plug 24 of the telephone receiver 23 into jack 12. This energizing circuit extends from grounded battery, through the winding of retardation coil 9, normal contacts of jack 27, transmitter 22, forward contacts of jack 1.2 lower normal contacts of relay 28, primary winding of induction coil 29, conductor 30, thence to ground through the normal contacts of relay 235 (Fig. 2). l

When it is desired to use a breast transmitter 31, in place of the switchboard transmitter 22, plug 32 of the transmitter 31 may be inserted in jack 27. The separated contacts of jack 2? will then disconnect transmitter 22 and the energizing circuit for 31 may be traced from grounded battery, through retardation coil 9, lower main members of jack 27 and plug 32, transmitter 31, upper main members of this plug and jack, thence to ground through the circuit already traced by way of the lower normal contacts of relay 28.

The circuit for the operators receiver 23 may be traced from the lower terminal of the winding 34 of transformer 33', upper normal contacts 0d of relay 28, lower main members of jack 12 and plug 24, receiver 23, upper main members of plug 24 and jack 12, upper normal contacts cab of relay 28 to p the upper terminal of winding 34.

A monitoring system, which when employed will inappreciably effect thetransmission relativeto the operators receiver 23, may be obtained by inserting plug 35 into jack 36, plug 37 into jack 38, and plug 39 into jack 41. Current from grounded battery will traverse a circuit over the lower main members of jack 3 6 and plug 35 to filament 43 of a three element vacuum tube amplifier 42- to ground over the sleeve. members of plug 35 and jack 3.6. Grounded battery also applies current through the upper members of 'aclr 36, plug 35 and primary winding of transformer 45 to the plate element 44 of the tube 42. The telephone receiver 40 is connected by way of plug 39 and jack 41 to the secondary or output winding of transformer 45. The main members of jack 38 are connected in parallel to the leads of jack 12 which. connect to receiver 23. Therefore, voice currents over the plug 37 will traverse a circuit through the primary winding of transformer 46, the secondary winding of this transformer is included in the input circuit of tube 42, which in cludes a grid element 51. When desired, the operators receiver 23. may .be disconnected from jack 12 and connected to jack 41 and used with the transmitter 31 in th regular handling of telephone connections, in place of the monitoring receiver 40. Under these conditions, it is immaterial whether 24 is in jack 12, transmitter 31, as already traced, is independent of the lower contacts, of jack 12. These contacts merely serve to complete the circuit for the transmitter 22. v

To connect the'operators receiver 23 and transmitter 31, with the respective sides'at the cord circuit C1, the key formed ,of units 220221 is operated. For the receiver, a circuit may be traced from the main conductor 203 of the cord, the upper normal contacts fig of key 210, the upper forward contacts 97" of key 220, the upper normal con tacts git; of key 230, conductor 236, the upper plug normal contacts fc of key 20, winding as of transformer 33, lower normal contacts (Z [if keyv 20, conductor 237, lower normalcontacts. 6 of key 230., the lower alternate contacts (Z0. of key 220, the lower normal contacts do of key210 to the oppositemain conductor 204 of the cord circuit. For the transmitter'31, the circuit istraced from the .inain, conductor 205, the upper normal contacts cf of key 211, the upper forward contacts kg of key 221, the, upper normal contacts ale of key 231, conductor 238, the upper normal contacts of relay 49, upper nor-- mal contacts dc, of key 21, secondary Wllldf. 'ingof the induction coil 29-, the lower nor- :mal contacts to of key 21 and lower normal contacts of relay 4:9, conductor 239, the lower normal contacts of key 231, the lower alternate contacts 0d of key221 and the lower normal contacts a?) vofkey 211 to. the

main conductor 206. With the circuits just traced, thereceiver 23 will be connectedun bridge on the upper side of the, four-wire cord circuit, while the transmitter 31 will be similarly connected to the lower side of the four wire cord circuit. 1

In case the splitting key'210211 is op erated at this time, the operators set will be connected to plugs 207 and 208 andm'ay be used for communication-over the radio circuits. If the splitting key is in its position to operate units 215216, the radio side will 'be disconnected and the. operators set will;

sertion of plug, 7 into jack 3 will separate be connected for usewith the line L. Operation of the key formed of un1ts2O 21 opens obvious connections which normally short circuit the series resistance units, while the forward contacts of the shunt resistance units are connected together to form a bridge path for the loss networks, which is of the ter may now be traced from conductor 203,

upper normal contacts ]L(/ of-key210, the

upper forward contacts gf of key 220, upper since the circuit for the alternate contacts fe of key 231, coiuluctor 238,. and as already/traced through the secthrough the winding 48 of the'transforme'r 33 returning overconductor 237, the lower alternate contacts ecZ of k'ey 230, the lower alternate contactsed of key 221, and the lower normal contacts Z766 of key 211 to the opposite main conductor 206.

' .The control described above,increases the flexibility of the connecting circuit, since it permits the transmitter and receiver of an operators set to be interchanged with respect to the sides of..the cord circuit C1,

whereby a'single operators setmaybe properly connected to talk, monitor or signal in either directiomwhether the communication takes place from line to radio or from radio to line. This is a distinct advantage, especially when repeaters are used between the cord circuit and the distant radio system, or

betweenthe cord circuit'and the four-wire terminating equipment of the two-wire line 14" orthe circuits of the four-wire line formed ofcircuits L1 and L2. When using a connecting circuit of this type it will be obvious that the repeaters render the respective sides of the four-wire'circuit opaque to currents in one direction;

such aconnecting circuit, the reversing key order to talk in the opposite. direction, it will be necessary to throw the reversing key to the opposite position. 'z

pon receiving a call signal fromthe line L, as indicated by the lighting of lamp 18 due to the locked position of relay; 17, in-

the normal contacts of this jack-t0 disconnect ground and thereby effect the release member of the plug 7'with the sleeve mem- In talking from the operators set in one direction over ber of the jack, therebypermitting the release ofrelay '17., Following complete insertion of plug 7- into jack 3, a circuit, in.

substitution of the first path, is completed over the sleeve conductor of plug 7, the lower normal contacts of key 220 to ground through therwindingof relay 201 (Fig; 2'). I

vThis providesthat during'the period of a connection, an incomingcall signal 7 locks up relay to supply the relay 17 over the sleeve conductor of the connection and the lower normal contacts of key 220, so as to maintain the signal lamp 18 lighted. lVhen the talking key 220-221 is operated in responding to such a signal, separation of the lower normal contacts of the unit 220 will open the locking circuit of the relay 17, thereby extinguishing signal 18.

To insure that the signal 18 will not be displayed due to inductive or surge effects in the conductors of line L, a slow release relay 16 is inserted between the alternating current relay and the signal control re- My 17 Relay 16 is normally energized over an obvious circuit which circuit is opened upon the operation of relay 15. Signaling current incoming over line L must hold relay 15 energized for a sufficient period to allow the contacts of relay 16 to assume the fully released position, in order to remove a shortcir'cuit about the winding of relay 17 For signaling outward over the line circuit L, the plug 8 is inserted in jack 5 and the talking key 220'221 operated. Key 240 istlren operated to apply signaling current from a source 241 to operate relay 242 which has a high impedance to signaling currents. Relay 242 causes the energization of relay 243 over an obvious circuit closure of the contacts of relay 243, connects ground to a circuit which extends through the lower alternate contacts at of unit 221, the upper sleeve member of plug 8, shell of jack 5, and the winding of relay 10 to grounded battery. The upper armature of relay 10 connects ground to the upper main conductor of line L, while the lower armatureconnec'ts the lower main conductor of the line to conductor now connected over the lower alternate contacts ab of key 240 through the source 241 and the upper alternate contacts cf of the key 240 to ground, whereby current is supplied to line L from the source 241.

Where a continually operating source of alternating current, as the source 241, may not be available, the key 240 may remain in its normal position, and the hand generator 244 operated. One side of this generator is normally grounded through the upper normal contacts de of key 240, while the opposite side of the generator is connected over the lower normal contacts 0?) of this key to the conductor 50. Under these conditions the relay 242, connected from the conductor 50 to ground, will respond to current from the hand generator and effect the operation of relay 242, which in turn causes relay 243 to operate; whereby ground potential will be applied over the sleeve of the connection to energize relay 10, while energy from the hand generator over conductor 50 will be effective over the lower armature of ringing current to line L. The operation of the current indicating system M may be described as follows. Let it now be assumed that, during the period of the connection or while in preparation for a connection, the plug 207 of the cord C1 is connected to the trunk 304 of the radio receiving equipment RR. Insertion of the plug 224 into jack 222 establishes :a circuit which may be traced from main conductor 203 over the normal contacts hg of key 210,

upper main members of the jack 222 and plug 224, the primary winding of transformer 286, thence over the lower members of plug 224 and jack 222 and the lower normal contact-s do of key 210 to the opposite main conductor 204. The sleeve members of rents will be respectively rectified in this tube to set up uni-directional currents through the meter 285. battery 284 is to neutralize residual current effects commonly referred to as Edison effect currents, and retain the needle of the instrument 285 normally at zero or at any other predetermined point or position on its associated scale. Therefore, with this stabilizing arrangement response of the needle will be due only to such alternating currents as may arrive from the connected circuit. By transferring the plug 224 to the jack 223 similar readings of voice or other signaling currents may be made relative to the opposite side of the four-wire circuits. The current measuring system M is described more in .detail in my Patent No. 1,404,311 dated January 24, 1922.

During the period of a connection, the operator may monitor by operating the monitoring key formed of units 225-226. A circuit for this purpose may be traced from the main conductor 203, upper normal contacts hg of key 210, upper forward con tacts f@ of key "225, upper normal contacts gh of key 230, conductor 236, normal upper contacts fe of key former 33, lower normal contacts do of key 20, conductor 237, lower normal contacts 0; of key 230, lower normal contacts (Z6 of key 220, lower normal contacts 07) of key 230, conductor 52, lower normal contacts of relay 53, winding 54 of transformer 33, upper normal contacts of relay 53, conductor 55, upper normal contacts M of key 230, lower forward contacts do of key 225, lower normal contacts do of key 210 to the opposite The purposeof the 20, winding 48 of transtelephone set which will now be in a posi-.

tion to monitor on the upper side; ofgthe four-wire cord circuit, which may be. assumed as connected to the trunk circuit 304 for the reception of voice currents transmit-1 ted from the radioequipment to the line L.

When desired, receiver may be employed for monitoring operations over the circuits .already traced through amplifier 42 tothe output windings 34 and56' of the transformer 33. Y w

During the monitoring period the transmitterof the operators set will, be rendered inoperative; Forthis purpose a circuit may be traced from ground through the upper forwardcontactsef of the key 226 to grounded batterythrough the windingof relay 49. In responding,,this relay opens the circuit of. the secondary winding ofthe induction coil 29 of the operators transmitter.

F or monitoring on the opposite side of the four-wire cord circuit, the key units 22 5226 are continued in theopcrated or monitoring position, while key units 23023l are also operated. The circuit may now be traced from the mainconductor 205 through the upper normal contacts 6; of relay 211, the forward upper; contacts do. of key 226, the upper alternate contacts z'h of key 230, conductor 236, normal contacts fe of key 20, winding 48 oftransformer 33, lower normal contacts do of key20, conductor 237, lower alternate contacts erlof key 230, lowernormal contactsefi. ofkey 221, lower alternate contacts ab of key 230, conductor 52, lower normal contacts ofrelay 53,'winding 54 of transformer 33, upper normal contacts of relay 53, conductor 55, upper alternate contacts [cl ,ofkey230, lower forward contacts 6a of-key 226, lower normal contactsab of key 211-to the opposite main conductor 206 ofthecord circuit. WVith the-circuits connected as described above, the operators telephone receiver will be coupled by the transformer 33 for monitoring on the opposite, i. e. lower, side. of the cord circuit; while the circuit of the operators transmitter, although associated with the upper sidev of this cord circuit, will continue to stand open at the separated contacts of relay 49, which-continues operated over the circuit already described.

TVhererepeater equipments are not pres ent intermediate the cord circuit and the line L, transmission currents from the line L, as Well as from the radio receiving equipment, will become efiective in the operators recei'verwhenit is connected to the conduc- 'tors 203 and 204- of the cord circuitfor monitoring purposes. These conductors,'

while forming the pathproper for-the currents to the wire side of the connection, may also be common to thevoice currents from the line L, the proper or-through path for which, however, is by way of the lower conductors 205 and 206 of the cord circuit to the radio, transmitting equipment.v At

the hybrid coil the voice currents may divide, a portion flOWlIlglntO the upper side.

of the four-wire circuit which includes conductors 203 and 204 of the cord circuit.

In case repeater equipments are present between the cord and the line L, the upperside of the four wire cord circuit will not.

be common to voice currents incoming from i the line L, due to the repeaters being opaque to currents in that direction. Therefore, in order to monitor su'ch currents, it'is neces sary to operate the reversing key v230 -231 to transfer the operators'receiver to thelower side, formed by the conductors 205 and 206 of the cord circuit. In a converse manner, thevpresence of the repeaters serves to completely isolate these conductors with respect to transmission currents arriving. from the radio receiving equipment, which currents in the main may be excluded by a suficiently accurate condition of balance be tween the real line L and the artificial line 6. lVhen the operators telephone set is. in position for talking over the cord circuit C1, key units 22022l' being in their operated positions :as already described, it is desirable that currents corresponding with the socalled side tone effects be present in the operators receiver by currents produced by the operators transmitter. These efiects are produced in the pres-ent system by means of transformer 33 as will now be described.

In the talking position of the circuits, winding 34 of the transformer will be connected to receiver 23, while winding 48. will be connectedin bridge on the conductors 203 and 204' of the cord circuit. -A circuit may now be traced in half tapped relation from grounded battery, through retardation coil 9, condenser'58, upper'alternate contacts of relay 53, wind ng 54 of transformer 33 and the lower alternate contacts of the relay to ground. I

During the talking period, relay '53 is'energized by current from. grounded battery through the winding of'this relay over lead 59, upper alternate contacts of unit 220 to ground through relay 201, as previously traced. Relay 201 is of the marginaltype and does not respond at this time.

v With the CllCLlltSiAZlCBtl above, it will be seen that condenser 58 and winding 54 of transformer 33, form a series path connected in parallel with condenser 60. This condenser is connected in: shunt acrossthe pri mary circuit of the operators telephone set. and constitutes a path traversed by such voice currents as may be set up when the transmitter is in use. Therefore, by employing a suitable capacity value for con denser 58,a predetermined amount of the voice currents, to serve as side tone may be set up in transformer 33 and will be supplied to the receiver 23 over the circuits already traced. Side tone effects are recognized requirements for proper transmission, as a speaker may thereby gauge the amplitude or energy of the voice.

On the four-wire circuit, where a relatively perfect balance obtains at the terminating equipment T of the line L with respect to the artificial line 6, no currents from conductors 205 and 206 will reach conductors 203 and 204-. of the cord circuit. In like manner, in case plugs 7 and 8 of the cord circuit are employed with the four-wire, circuit formed of lines L1 and L2, voice currents from the operators transmitter, when connected to conductors 205 and 206, will not reach the upper side of thecord circuit formed by conductors 203 and 204. Therefore. the necessity for providing the side tone feature will be evident.

Cord circuit C 1) may also be employed with the toll line L. Plug 72 may be inserted in jack 61 and a connection established by plug 73 either to a trunk circuit 325, a line circuit 326 or a tandem circuit 327. The cord circuit C which is of the twowire type may also be employed in establishing the connections between the circuits 325 and 327 or between other two-wire circuits not shown but present in the system.

In describing the two-wire circuits, it will be understood, as already mentioned, that the cord circuit equipment C3 (Fig. 3) may be a duplicate of the cord circuit C. Assuming that a call has originated over the trunk circuit 325 by the insertion of plug 73 of the cord circuit G into jack 330 of trunk 325, a circuit may be traced from grounded battery, lower right hand winding of repeating coil 62, lower normal contacts a?) of ringing key 63, center or ring members of plug 73 and ack 330, relay 331 and thence to ground through the upper normal contacts of jack 332. at the opposite end of the trunk circuit.

The response of relay 331 completes a circuit from grounded battery over resistance 333, signal 334, contacts of relay 331 to ground through the lower normal contacts of jack Plug 73 in jack 330 effects separation of the normal contacts of the jack and by closure of the lower contacts, current from grounded battery traverses a resistance 339, signal 338 and thence over the local or sleeve members of jack 330 and plug 73 to ground. At this time signal 338 serves as a guard or supervisory signal.

In response to this call, a plug 335 of the cord circuit C3 may be inserted into jack 332. This effects separation of the normal contacts of jack 332 and closure ofthe lower alternate'contacts, thereby connecting a resistance unit 336 in parallel with and shunting signal 334. Ground over the sleeve members of the jack 332 and plug 335 being provided by the cord circuit, in substitution of the ground at the lower normal contacts of jack 332.

Since the cord circuit C3 is a duplicate of the cord circuit C, current will be supplied from grounded battery of cord C-3 over the center or ring conductors of the plug 335 and jack 332 to the winding of relay 337, the upper or tip members of jack 330 and plug 73 through the upper righthand winding of repeating coil 62 to ground. The corresponding grounded battery, present in the cord C, will cause current to traverse relay 331 to ground through the repeating coil of the cord 03 to maintain relay 331 energized. Resistance 340 will now be connected by the forward contacts of jack 330 and contacts of relay 337 to ground over the sleeve members of the connection to the cord C, thereby extinguishing signal In establishing the operators telephone set with the two-wire cord circuit C, key 65 will be operated. The upper contacts cf of this key provide a ground connection for the circuit through relay 28 to grounded battery, thereby effecting response of the relay 28. A circuit is established which may be traced as follows from the upper main conductor 66 of the cord C by way of the second upper forward contacts 0d of key 65, left hand winding of repeating coil 68, condenser 69 and lower forward contacts (lb of key 65 to the opposite conductor 67 of the cord.

-When the relay 28 operates, a circuit is established which may be traced as follows. From ground over the primary winding of repeating coil 68, lower alternate contacts of relay 28, transmitter 31 and retardation coil 9 to grounded battery, while another circuit extends in half tap relation from the upper terminal of the secondary winding of induction coil 68 by way of the upper alternate contacts of relay 28, receiver 23 and next upper alternate contacts of relay 28 to an intermediate half tap oint on the secondary winding of induction coil 68. The separated contactsv of relay 28'disconnect the transformer 33 and also induction coil 29 employed for four-wire working, as already described. For the circuits just traced, the forward contacts of relay 28 connect transmitter 22 and receiver 23 to operate by way of induction coil 68 in twowire relation to the circuits of the cord circuit C.

'lhe gnal at either end of the trunk circuit may be flashed by the removal and fit) till

re-insertion of the plug at the opposite end of the trunk, while "removal of a plug Will cause the signals at each end of; the circuit to be energized. To render this clear, remoral of plug 73 from thejack 330 effects the release of relay 33L, thereby disconnecting the shunting resistance 336 to permit the illun'iination oi signal 33 l by current -from grounded battery througl'i; resistance 333, signal 334, sleeve ine'n'ibers of jack 332 and plug to ground on the cord circuit C3. In case the plug 73 isnow re-inserted in jack 330, re-operatiionoi relay 331 will re-apply resistance unit 336 in parallel with the circuit just traced tor the signal 334, thereby of relay 381 removes the shunt path around causing this signal to be extinguished.

' From the description ust given, it will be apparent that a single relay having a single forward contact,as the relay 331,1n

association with jack and cord circuit C 3 will serve either asa line or supervisory signal control relay in the handling of telephone traffic over the trunk circuit 325. in a reciprocal manner, a corresponding relay 337 may serve as a line or supervisory signal control relay for calls originating at jack330. i i Assume now that a call has originated at a station such as 378 on tandem circuit 327. In initiating thecall, removal of the receiver from its switchhook at station 378 completes a circuit which may be traced 'i rom grounded battery 725 over resistance unit 379, first lower normal contacts of jack 380, relay 381, first lower normal contacts of jack. 38:2, thence through the instrument station 378, through relay 383, upper nor-. nial contacts of jack 382, marginal relay 38a, upper normal contacts of jack 380. and resistance unit 385 to ground.

transmittim station lu 73 of cord circuit C will be inserted into jack 380. The lower group of contacts otjaclr 380 effect disconnect on of grounded battery through the winding of relay 201 (Fig. 2) and establish a shunt on signal 386 as already described for the call over trunk circuit 325. Separationot .the first lower normal contacts of jack 380 opens the circuit over which current is supplied through resistance units 379 and 385, current and ground being. new

substituted by way of repeatingcoil 62 0f' Due to the presence oi resistances 379 and 385 in the the cord circuit to the main conductors of station 378, the marginal relay 384 will resp ond. The contacts ,of'this relay establish a shunt path around relay 383 which will now release and disconnect signal 387. hen the receiver is restored to its switchhook at station 378, cessation of current through the main conductors of the line will etl'ect releaseot" relays 384: and 381; Release 23, to effect display ofthe signal which at this time is a disconnect indication. Assuming now that the call received from station 378 is to be answered at the switch board of the radio receiving station, lamps 386 and 387 will be lightedfas explained above and the call willbe answered by inserting plug 335 01": the cord circuit C3 into jack 382. The upper and first upper normal contacts of this jack now disconnect the cir-V cuit fromthe distant jack 380, thereby etfecting the release of relay 381 to extinguish signal 386 atcthe latter point, while battery over the ring conductorfot' the cord circuit C3 will traverse the circuit, through the instrumentat station 378, returning throughrelay 383 over the tip members of the'connection to ground on the repeating coil of cord C3. Circuitchanges, due to the presence of plug 335 in jack 382 and the operated position ot'relay 383, serve to shunt the lamp 387. On disconnection at station 378, relay 383 will be released, thereby effecting removal'ot the shunt path and permitting signal 387 to be displayed. 7

Let it now be assumed that an operator at'OT .(Fig. 1) desires to call station 388 of line 326. Plug 73 will be inserted'into jack 389 thereby disconnecting roundrand battery from the main conductors of this line due, to, separation of the normal cont acts of the jack. A signal 390 will be lighted at this time by current from the grounded battery through theassociated resistance unit, signal 390 and sleeve .mem-

bers of the plug and jackto ground on the cord circuitC. Operation of ringing key 63 and hand generator 2%, serve to apply ringing current over conductor 50,lower alternate contacts of 'key 63, ring members at station 388, flow of direct current through the repeating coil. of the cord circuit will effect the response of relay 391 to eiiect shunting of signal. 390. Under flashing or disconnect operations as station 388, relay 391 will be alternately energized and deenergized to respectively display or extinguish the signal 390 in a manner similar to that already described for flashing and disconnect operations in the trunk circuit 385.

When desired, the jack 61 of the line L may be employed for so-called patching of this line to come primarily under the control of the switching equipment at the distant radio station, or this line may be patched directly to the circuits 325327 for service therewith. A patching cord, not shown, but well known in the art, may be associated with jack 61 of the toll line and with jack 315 of the trunk circuit 318. In turn, a second patching cord may be associ ated from jack 317 to the jack adjacent the plug 321 thereby providing that the line L may terminate at the duplicate equipment 'I1 at the radio receiving station. This prepares circuits so that the four-wire cord circuit C2 may be employed for establishing connections between the land line L and the radio transmitting and receiving equipment in the manner already described for connections established at the other switchboard. Similar combinations relative to parallel, series or tandem or combinations of parallel and series connections may be carried out relative to the two switchboards in a similar but inverse manner to the arrangements already described.

In connection with the radio transmitting system, a coil 392 may be positioned adjacent the electromagnetic equipmentof the trans mitting circuits, or of an inductive turn, as shown in the antenna lead. As shown, the coil 392 may connect to suitable amplifierrectilier equipment 393 for causing the relay 394 to respond during the periods that energy is supplied to the antenna. This results in the application of current from grounded battery over an obvious circuit through rela'ys 395 and 306 to energize the respective signals 397 and 398 at the two switching points. The display of these nals indicates to operators at the respective stations that the radio transmitting system is energized for use.

call signal, incoming over the radio side. may comprise two alternating currents of diiierent frequencies as modulations of the carrier wave. Upon detection or the incoming wave by the radio receiving equipment, an impulse of current comprising the two different frequency currents will become effective to cause two correspondingly tuned relays 399 and 399-2; to respond.

eaters Simultaneous separation of the normally closed contacts of these relays releases relay 701 which is normally energized over an obvious circuit. Relay 701 in releasing applies current from grounded battery through relay 702, relay 703, normal contacts of jack 310, relay 704 to ground through the normal contacts of jack 303. Response of relays 703 and 704 apply grounded battery through obvious paths to respectively energize signals 705 and 706.

The call. may be answered at either switching equipment and, assuming that response is made at the first switchboard, insertion of plug 207 of the cord G1 into the jack 303 effects the separation of the normal contacts of this jack to disconnect the-circuit through relays 702, 703 and 704. However, these relays were held energized, following the response of the relay 702, by current from a grounded battery connected over the alternate contacts ofthe relay 702. This battery having been thereby substituted for the battery initially connected over the contacts of relay 701. hen the plug 207 is fully seated in jack 303, a circuit will be prepared from ground through relay 201, upper normal contactsot key 220, upper sleeve members of plug 207 and jack 303, thence over the now closed alternating contacts of jack 303 to the circuit'already traced through relays 704, 703 and 702. Therefore, during the period of a connection, a subsequent call signal will effect the response of the relays 399 and 399A to cause the re-operation of the relays 702, 703 and 704 to display signals 705 and 700 as already described. 0

In responding to such asignal, operation of the talking key formed of units 220-221 disconnects the circuit to ground through relay 201 at the upper normal contacts of the key 220. effecting release oi relays 702, 703 and 704 thereby restoring the signals 705 and 706 to normal, or non-operated position.

For call signaling. over the radio link, the plug 208 is inserted in jack 305, key 215210 of cord circuit C1 is now operated, followed by the operation of a master signaling key 245. Current from sources 240 and 247 willflow over the main conductors of: the plug 208, jack 305, to the 'adio transmitting equipments TR and a carrier wave modulated by the current from the sources 240 and 247 will be supplied to and radiated frol'l'i the antenna 302.

At a distant point, such as at a station equipped as shown in Fig. 4, the called signal modulated wave will be received by an antenna 400, detected by the receiving equip ment 401, and the detected currents will be supplied to the two correspondingly tuned alternating current relays 402 and 403. Simultaneous operation of these relays opens the connection to ground of a circuit including the relay 404 which is normally energized over an obvious circuit. On release, the latter relay connect-s grounded battery to a circuit through relay 4.05, resistance 406 and thenormal contacts of jack 408 to ground. \Vh'en the relay L responds, its contacts connect a second grounded battery, in substitution of the first mentioned battery over the contacts of relay a to reta n relay 405 energized and also to supply current through signal 407 and thenormal contacts of the trek 408 to ground.

For telegraph operation. ke 271 of the equipment 'S-1 (Fig. 2) may be momentarily operated. thereby applying current from grounded battery through relays 235 and 232 to ground. In responding, separation of the upper contacts of relay 235 disconnects a normally closed path in shunt 'to the output Winding of transformer 2&8. On closure of the lower contacts of relay 235, grounded battery is applied through normal contacts of key 2&9, signal 250 and relays 235 and 22 to retain these relays energized. The contacts of relay connect the secondary Winding of the transformer 251 to energize the cathode or filament 252 of a three-element vacuum tube 253; the primary Winding of this transformer being energized from a source From an intermediate half-tap point connecting units 255 and 256 connected in series to form a bridge across the filament 252,' a circuit may be traced through B battery 257,'retardation coi'l258, theprhnary Winding of an output transformer 25!.) to the plate element 2600f the tube 253. The coudensers shown'connected from the retardation coil to points of the plate circuit serve to establish a. condition of resonance relative to a certain frequency, which in the present case may be assumed as one thousand cy-cles per second.

Upon. closure of key 261, grounded battery isconnectedthrough relay 263, retardation coil 262, key 261to ground. The re sponse of relay 263 closes a circuit which may be traced from the filament by Way of resistances 255 and 256, through the secondary Winding of transformer 25S) and contacts of relay 263 to the grid element 26;: of tube 253. The latter circuit forms a socalled feed back to produce and maintain the production of oscillations in the tube circuit. These oscillations are supplied to transformer 248 by Way of an intermediate transformer 265.

Assuming now that the plug 208 is present in jack 305 with the talking key units 220-221 in their operated positions, alternating current of one thousand cycles per second Will be supplied from ground through the right hand Winding of transformer'248, conductor 30, the primary Wind- 205 and 206.

to the antenna 302.

. ployed for talking,

31 to ground through the condenser 60. I

As already described, the operated position of key. 221 connects the secondary Winding of induction coil 29' and with "conductors Itthe refore iollows that each closure of the telegraph key'26l will result in an impulse of alternating current, which traverses the connection over theplug 208 and jack 305, to the radio transmitting equipment RT from which it will be supplied as a modulation of the carrier wave The right hand Winding of transformer 248 is of low ohmic or direct currentresis ance theretore,'it is substantially innnaterial Wlretherthis Winding is in series With the battery supplyottransmitter' 31, as already.v traced through the Winding of induction coil 29. Accordingly, during the periods "when relays .235 and are energized as indicated by'the display of signal. 250, the operator may either talk or telegraph over the radio transn'iitter; i. -e.,'during periods when the telegraph key 26l is-at rest the transmitter 31 may be em- 4.- Y 1 telegi aphm bnnilar equipment at a distant radio station may be operated for telegraph signah ling, the signals being ,received by Way of the antenna 801 and radio receiving equipment RR; Atter detection in the receiver RR the signal impulses will be transmitted ceiver 23 forreception of suchineon'iing telegraphic signals. Without other manipulation on the part of the operator. A key 76 may be operated it desired to apply ground to the transmitter circuit and there by 'shunt the transmitter 31 for the alternating telegraph signal currents. This key mayalsobe employed as a transn'litter cutoutkey at any time in the handling of telephonetrattid, I i 1 i The systen'roi direct current telegraph, employed with the present system Will now be described. A pole changer or telegraph key 707 line relay 708, and a vibrator sounder 709. controlled by the line relay and energized from an alternating current source 710 by Way'oi a transformer 7ll, may

While upon cessation of, talking the key 261 may be operated for Hill its,

form one station on. a line conductor 712; while a, similar key 266, line relay 267 and. sounder 268 1nay be present at asecond sta- "267 to respond to respectively operate the sounders 709 and 268 when signals are transmitted from the right hand to the left hand station. In a reciprocal manner, operation of the key 266 serves to transmit signals from the left hand to the right hand station. The sounder 268 is supplied with energy from the alternating current source 275 by way of a transformer 276, which also supplies energy for the sounder 277.

WVhen desired the Morse line 712 may be connected to control the system for transmitting telegraph signals over the radio channel. This may be effected by operation of key 269. Assuming the latter key is in its operated position and sending under way from key 707, each closure of the contacts of the line relay 267 establishes a circuit from ground by way of key 269, retardation coil 262 and the winding of relay 263 to grounded battery, causing the latter relay to respond and control the feed-back circuit of the oscillator 253 in the same mannor as that already described for controlling it from the telegraph key 261. Further, assuming that plug 208 is present in. jack 305, direct current signals from the Morse line 712 will be translated into alternating current impulses at 1000 cycles per second which will be supplied by way of the transformer .248, induction coil 29, talking key 221 and the connection previously described to the radio transmitting apparatus and antenna 302.

The arrangement whereby busy test operations may be carried out by means of the cord circuit C may be described by assuming that the talking key 65 of this cord is in its operated position. Relay 28 will now ope ate due to grounded battery through the relay to ground through the upper forward contacts of the key 65 as already described in transferring the operators receiver and transmitter 31, respectively, from the transformer 33 and induction coil 29, to con trol through the induction coil 68.

Assume now that the upper or tip me1nber of plug 72 is applied to the sleeve of the jack 33-0 in performing a busy test operation. Current from grounded battery, through the resistance 339 and signal 338 to the shell or sleeve member of the ack 330, will traverse the tip strand of the cord circuit as connected by way of the upper normal contacts of the ringing key 71 to ground through the upper left hand winding of repeating coil 62. This current effects a change of poten' tial level hetwccnthe main conductors (it; and 67 of the cord circuit, which becomes effective through the condenser (39 and the secondary winding of the repeating coil 68 to cause a click in the telephone receiver 23. In the present instance this click may be taken as an indication that the line 825 is idle.

In the event that a cord, similar to the cord circuit C, is connected to a jack associated. with. the jack 330 on the line 325,

ground potential from the sleeve conductor of such. cord circuit to the shell of the jack, will prevent How of current from grounded battery, as described when the tip of the plug 7 2 is inserted into jack 330. In such a case, absence of a click in the telephone re-. cci'ver is an indication that the line 325 is busy.

l Vhere it may be desirable, the order of the busy test indications may be reversed, that is, for an idlecondition of a circuit no click will be present, while for a busy line, a click will be heard in the operators telephone receiver when the tip of a plug is touched to the shell of a jack on a line or trunk which is busy. This may be done by reversing battery and ground for the sleeve or local circuit of a cord and jack. For example, on the trunk 825 the resistance 339 may be connected to ground instead of to a battery, while the sleeve strand of the cord C may be connected to battery instead of to ground. Again the winding of the auxiliary signal relay 201 may be connected to battery instead of being grounded, as shown.

The equipment for a ship or similar station (F 4) may comprise an antenna 4.00 connected to a receiving equipment 401 and also to a transmitting equipment 411. In establishing connection of a telephone set to the radio transmitting and receiving apap aratuses a cord 4-12 is used to connect jacks 413 and 414, and similarly a cord 415 is used to connect conductors 408 and 416. Over the main jacks of the respective cords and the main contacts of the jacks, with which they are associated, the output and input windings of transformers 417 and 418 will be respectively connected to the radio transmitting and radio receiving equipments. To connect an operators telephone equipment GT2, comprising a transmitter 419 and re ceiver 420, with the radio equipment a talk ing key, formed of units 421 and 422, is operated.

For the transmitter a circuit may now be traced from the upper terminal of the right hand or primary winding of the transformer 41?, lower normal contacts be of a key 423, upper normal contacts gh of this key, lower normal contacts 72d of key 424, conductor 46h, upper normal contacts jh of key 425, lower. forward contacts at of the key 4-21, the secondary winding of induction coil 426, upper forward contacts 0/ of key 421, upper normal contacts 7'Jy' of the key 4 5, conductor 465,11pper normal contacts eg of the key 424, the upper normal contacts M of the key 423, the lower normal contacls ft: of this key to the lower terminal of. the primary winding of transformer 417.

For the receiver a circuit may be traced from the upper terminal of the secondary winding of the transformer 418 over the upper normal contacts kg of key 427, lower lllll normal contacts 06 of this key, upper normal contacts fe of key 428, lowernormal contacts fa of key 425, upper forward contacts er] of key 422, winding 429 of transformer 430, lower forwardcontacts ha of key lower normal contacts of key 425, lower normal contacts do of key 428, lower normal cont-acts cf of key 427,'the upper normal contacts 770 of this key to the lower terminal of the secondary winding of the transformer 418. y

Voice currents from the transmitter 419 will be suppllied through the repeating coil 426, over the circuits traced above, to the radio transmitting equipment 411 and voice modulated carrier waves will be supplied to the antenna 400. Voice or signaling modulated carrier Waves incident upon the an-.

tenna 400 will be supplied to and translated in the radio receiving equipment 401 to produce voice or signal currents which will be supplied over the circuits traced above, including the transformer 430, to the receiver 420.

Communication, by means of the ship equipment described above, may be effected with anothership having a similar equipment, or communication with a land station similar to the station shown on Fig. 3, or

with stations including equipment similar to that shown in Fig. 5, to be hereinafter described.

A. connection for a communication over the radio channel may be made to different telephone stations aboard ship. To llltlS-r trate how this may be done, an extension of the connection to station TS will be traced. 431 when operated complete a circuit which may be traced as follows. From the upper terminal1 of the secondary winding of mduction coil 432' at the station TS over the upper, forward contacts ml of key 410, upper normal contacts of key 433, upper normal contacts 6g of the key 424, thence over the circuit already traced through the contacts ihj and fe of'key 423 to the lower terminal of the primary winding of the transformer 417. .The-connection from the lower termi-' nal of the secondary winding of the induction. coil 432 extends over the lower forward contacts 12a of key 410, lower normal contacts of key lower normal. contact-s (Z?) through the key 424 thence to contacts lag and ob ofthe key 423 already traced to the upper terminal ofthe primary winding of the transformer 417.

From the right hand terminal of the telephone receiver 434 a path extends, over the upper forward contacts. of key 431, upper forward contacts of the key 435, upper normal contacts, cf of the key 428, thence through contacts 710 and h of the key 427 already traced to the upper terminal of the secondary winding of the transformer 418.

A key formed of groups 410 and- From the lefthand terminal of receiver 434 I a pathextends over the lower forward contacts of key 431, lower normal contacts of key 4.35, lower normal contacts do of the key 428 thence through contacts cf and of key 42? to'the lower terminal of the. secondary winding of the transformer 418. When the receiver 434 is removed from the switchhook at thestation TS, the transmitter 436 will be connected to such speech currents to the radio transmitter 411, from i which a speech modulated carrier wave is supplied to the antenna 400, the receiver 434 will be connected to receive speech currents tov the radio receiver, which is connected to the antenna400.

l Vhen the receiver is replaced on the switchhook at the station TS, during a period of a communication, a circuit will be completed as follows. From grounded battery through a signal device or lamp 437, the upper. normalcontacts fe of key 438, upper alternate contacts fg of key 410, normal contacts439 under control of the switch-hook thence to ground through an audible signal device 440. Signal .437 indicates to the operator that disconnect has taken place at the station TS and therefore, thekey 410 -431 may be restored to'normal.

Assuming that the circuit is in normal condition and a call is initiated at the station TS. Removal of the receiver 434 from the switchhook establishes a circuit from ground through a signal 440, contacts 441 of the switchhook mechanism, the upper normal contacts cf of key 410, the upper through signal-437 to grounded battery. Display of the signal 437 serves as a, linesignal for this call, while the signal 440 may be continuously energized until responseto the call has been made by the operation of "normal contacts 6; of key 438, thence' key 410431. When the circuits are in v normal condition already traced and receiver 434 is replaced, the path for the lamp 437 will be transferred by the upper contactsof the key 410 for control through the contacts 439 of the switchhook mechanism, This again gives the disconnect signal and key 41043l is returned to normal position. The equipment at the station T81 is a duplicate of the equipment at the station TS and is under the control of akey formed of units 442 and 443. The instrument atthis station may be connected for service through the radio equipments.

Equipments represented by 444 and 445 may be used to insure secrecy of the communication over radio channels. Assuming that a station equipped as shown in Fig. 4 is in communication with another ship or station similarly equipped, the devices 444 will operate to mutilate in apredetermined manner the voice or signaling currents. outgoing over the sending radiochannel At ated.

the distant vessel an equipment, corresponding with that at 445 will operate to restore the signals or speech currents to their normal condition of intelligibility before they are supplied to the receiving devices.

The key formed of units 423 427 is used to connect or disconnect the equipments 444 and 445, for secrecy communications, be tween the telephone set and the radio terminal apparatus. Assuming now that these keys are in their operated positions, a circuit will be provided from the upper terminal of the secondary winding of the trans former 417 over the lower alternate contacts M of key 423 through the apparatus 444, upper alternate contacts 17c of key 423, the upper normal contacts ge of the key 424, thence to the conductor 465 which may lead to the operators transmitter 420 or to the transmitter of the stations TS or TSl, over the circuits already traced. The lower terminal of this winding of the transformer 417 is connected through the lower alternate,

contacts ed of key 423, equipment 444, upper alternate contacts z'h of the key 423, thence through the lower normal contacts lid of key 424 to conductor 466 which may be connected to either the transmitter 420 or the station TS, T51.

For the equipment 445 a path extends from the upper terminal of the secondary winding of transformer418 over the upper alternate contacts M of key 427, equipment 445, lower alternate contacts (Z6 of key 427, lower normal contacts 0d of key 428 to the conductor 460, while the lower terminal of this transformer winding is connected over the upper alternate contacts M of key 427, the equipment 445, ab of key 427, thence through the upper normal contacts f6 of key 428 to the opposite conductor 461, whereby either the opera tors receiver 420 or the receivers of the stations TS, TSl may be connected thereto according to the positions in which the various switches already described may have been placed.

A key 447 under control of the operator serves for establishing communication with the station TS2at which may be located the devices 444, 445 of the secrecy system as well power and other equipments for the radio system. In initiating a call from the station TS2 removal of the receiver from the switchhook at that point applies ground over contacts of the switchhook mechanism, the normal contacts do of key 447, thence through signal 448 to grounded battery. In response to this signal, the key 447 is operlt hen this is done the circuit of the signal device 448 will be switched to the now separated contacts 449 of the switchhook mechanism where the circuit will stand open. A circuit may now be traced from the upper terminal of the secondary winding lower alternate contacts ary winding of an induction coil 452, the

lower group of forward contacts at of key 447, resistance unit 453, the lower terminal of the secondary winding of the coil 426. A second circuit may be traced fromthe up per terminal of the winding 429 of transformer 430, resistance 454, the lower contacts be of the key 447, thence through the induction coil 452, receiver 451, the upper contacts gh of key 447, resistance unit 455, to the lower terminal of the winding 429 of the transforn'ier 430. With the circuits just traced the transmitter 419 and receiver 420 of the operators equipment will be connected for communication with the equipment at the station TS2. When the receiver is restored to its switchhook at the latter point, ground is applied through the contacts 449.to supply current to the signal lamp 448 which is lighted, thereby indicating a disconnect condition; whereupon the key 447 will be restored to its normal position.

A key 456 at the operators position and a signal 457 at station TS2 serve as a means for calling from the first to the latter point.

In case it is desired to reverse the relation of the operators transmitter and receiver with respect to the outgoing and incoming radio channels, a key 425 may be operated. In its operated position and assuming that the key formed of units 421-422 is in its operated position, a circuit for the transmitter may be traced as follows. From the upper terminal of the secondary winding of the induction coil 426, upper forward contacts cf of the key 421, upper alternate contacts cl of the key 425, upper normal contacts cf of the key 428, thence through normalcontacts b0 and gh of the key 427 as already traced to the upper terminal of the right hand winding of transformer 418. From the lower terminal of the secondary winding of the coil 426 the connection extends over the lower forward contacts 5a of the key 421, the upper alternate contacts M of the key 425, lower normal contacts do of the key 428, thence through normal contacts of and of key 427 to the lower terminal of the winding of the transformer 418. From the upper terminal of the winding 429 of the transformer 430, a path extends through the upper forward contacts ad of key 422, lower alternate contacts cd of key 425, upper normal contacts cg of key 424, thence through normal contacts 707' and fa of the key 423 to the lower terminal of the right hand winding of the transformer 417. The lower terminal of the winding 429 of the transformer 430 is connected over the lower forward contacts bar of key 422, lower alternate contacts ba of key 425, lower normal contacts db of key 424, thence through noriao stands hereinafter.

mal contacts hg and-c?) of key 423 to the upper terminal of the winding of thetranstormer417 v In this position of the circuits it will be clear that the; transmitter 419 connected to the lower channel through the transformer 418 while the receiver 420 stands connected to the upper channel through the. transformer 417.

For monitoring on the connection ust described, a key formed of units 458459 is moved to its operated position. A path from conductor 461 of the speech circuit connected to theincoming radio channel may be traced over the lower normal contacts fee of key425, upper alternate'contacts @(Z of key 459, winding 462 ofthe transformer 430, lower normal contacts of the key 422, winding 429 of the transformer 430, lower forward contacts ha of key 459, lower normal contacts to of key 425, to the opposite conductor 460 of the speech circuit associated with the incoming radiochannel. The windings 429 and 462 of the transformer 430 are connected in series across the incoming radio channel to form a bridge to which the receiver 420 is coupled for monitoring. The increased impedance due to addition of the winding 462 at this time results ina conditionot substantially zero loss as regardsthe incoming transmission. I lVhen monitorii'ig on the circuit just described the key 458 serves to disconnect a sidetone circuit, in a manner to be described PAgain, operationof the reversing key 425 serves to transfer-the circuits of the receiver 420 from the conductors 460 and 461 of the'incon'iin'g side of the radio chaunel to conductors i465 and 466 which, as alreadyztraced, constitutes part of the speech circuit associated with the outgoing radio channel, thereby permitting the operator to n'ionitor'on'either the incoming or outgoing channel. v v v During periods when the operators telephone set is in the talking position, aside tone circuit from the transmitter 419 to the receiver 420 is provided over a path from the upper 't-crn'iinal of the transmitter 419 by way of a condenser 463, normal contacts of key 458, winding 462.01 the transformer 430' unaer normal contacts of the he 1 ll 459, and resistance unit 464 to the lower terminal i of the transmitter. The wind.- ing 462 in this instance serves to supply re ceiver 420 with a predetern'iined amount of' voice current from the transmitter 419. During the monitoring period, as already described the winding-462 is disconnected relative to the side tone circuitand connected with the windii'ig 429 of the transformer'to 'fOIHI a high impedance bridge path across av speech circuit of the radio channel,

- Call signaling may be etl'ected by operating a key formed oi the units 424428 and a 'key'467. Operation of these keys completes alternate contacts by of the key: 424, thence through normal contacts .lcj and f6 of the key 423 to the opposite terminal of thewindi'ng oi the transformer 417. 470 and 471 represent alternating current sources, which for convenience may be similar to the oscillator system S1 (Fig.2). The current supplied by sources 470 and 471 will be of respectively dillerent' frequencies and on arriving at a distant stat-ion, snmlar to the statlon shown in Mg. 3 or the station being described and illustrated. in Fig. 4, are used to energize.

two relays, corresponding with either relays 399 and 3994 or 402 and 403, to control a signal device as already described in connection with the signal receiving systen'i of Figs. 3 and 4. I i

hen the station TS is connected over four vire circuits to the radio transmitting and receivingequipments, voice currents for side tone efi'ects may traverse a relatively high impei'lance circuit tormed vby a con: denser 483 and resistance unit 484 connected from the terminals of the transmitter-436 in bridge on the main leads of the receiver 434. A corresponding resistance. and condenser nerve the same purpose for sidevtone, eltects when four ,wireis used to connect the. station TSl tothe radio apparatuses. v A group connection between stations Tb, Till and TS2may be had by operation of the keys formed of units 438, 446, 495 and 496 and also 447'. hen these keys are operated, the instruments will all be connected common to the conductors4i'9 and 480 for so-called conference communication. At such times the operators transn'iit'ters 41-9 and 420 may also be included in such a connection over circuits already traced toeconductors479, 480, 485 and 486. v a

The radio-wire system shown in Fig. 5 may be used at a station which is adapted for communicating with other land lines for telephony, or may be used for. communication by radio with ship stations or other land stations'ot the type described above. A line circuit L4 is connected through a jack 500, a. signaling key 501,,onepair1of terminals of the series winding ota hyhrid COlltlZtIlSfOlll'lEl' 502, the other pair of the terminals of the series winding beingconnected to an artificial line or network, 503

which electrically balances the line L4. The upper output winding-pf the/hybrid coil 502. is connected through a splitting key 504 to conductors 505 and 506.1 The bridge points. of the hybrid coil ,502 are. connected i

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