I B. P. HAMILTON CARRIER TELEGRAPH CIRGUIT'S Filed 001;. 21. 1 920 2 Sheets-Sheet 1- m. 2', 1 23. 1,%&
B. .P. HAMILTON CARRIER TELEGRAPH CIRCUITS Filed 00f. 21, 1920 2 sheets-sheet 2 MW 651 45 @Z 12 6g ME in? r1 INVEN'EOR ATTORNEY iFatented Got 2, 11 923..
UNHTETD. STATES insane saranr or ies.
BAXTER 1P. HAMILTON, OF BROOKLYN, NEW YORK, ASSIGNOR TO AMERICAN TELE PHONE AND TELEGRAPH COMPANY, A COBPGRATI ON OF NEW YORK.
CARRIER TELEGRAPH oraourrs.
Application filed October 1920. Serial No. 418,486.
To all whom it may concern;
Be it known that I, BAXTER P. HAMILTON, residing at Brooklyn, in the county of Kings and State of New York, have invented certain Improvements in Carrier Telegraph Circuits, of which the following is .a specification. A
This invention relates to signaling systems, and more particularlyto systems in which telegraph signals are transmitted by means of carrier currents.
One of the objects of this invention is to provide a repeater apparatus for carrier telegraph systems, said repeater apparatus being soarranged that a local subscribers circuit or loop may be associated therewith for the purpose of transmitting signals to and receiving signals from the repeater apparatus. 4
Another object of the invention ,is to pro vide means whereby a subscribers loop will be associated with the repeater apparatus and repeater telegraph system in such a manner that the loop'will operate for the transmission of signals to and from the re' peater upon a half duplex basis. Another ob'ect of the invention is to provide means w ereby a subscribers loop will be associated with the repeater apparatus and repeater telegraph system in such a manner that the loop will operate for the transmission of signals to and fromthe repeater upon a full duplex basis.
Other and further objects of the invention will be clear from the following description when read in connection with the accompanying drawings, Figures 1, 2, and 3 of which illustrate circuit diagrams embody ing a number of difl'erent formsot the invention, and Figs. 4 and 5 otwhich show the detailed circuit arrangement of the carrier transmitting and receiving apparatus used in connection with the repeater.
Referring to Fig. l, M-LE and MLW designate transmission line sections over which carrier currents may be transmitted.
' A transmitting circuit TLE and a receiving circuit RLE are associated with the main line section MLE through a balanced transformer 10, an artificial line and network, MNE, being provided for balancing the main line circuit. For. the same purpose transmitting circuit TLW and receiving circuit- RL W are associated with the main line IVILW through *abalanced transformer 10 and balancing network MNW. A plurality of carrier channels may be associated with each of the transmitting and receiving circuits above described for multiplex work.
For purposes of illustration, a single channel is shown associated with each circuit; thus a transmitting channel'- associated withthe circuit 'l'LE is illustrated as comprising a transmitting amplifier TAE, to which an oscillator (1E may be connected under certain circumstances as more fully explainedhereinafter. A similar transmittin amplifier TAW and oscillator GW are s ownas being associated with the circuit RLW. The amplifying arrangements above described may be of any well-known form, such as, -for example, vacuum tube amplifiers. The genera-tors may also be of any known character adapted to enerate a carrier frequency, but are preferably vacuum tube oscillators. A typical arrangement of oscillator and amplifier is illustrated in Fig. 4. In practice, when the apparatus is used as a through repeater, the generator is unnecessary, and will be disconnected from the amplifier at the points indicated by the crosses. The filament of the amplifying tube will, in such case, have its circuit completed to battery directly through a resistance (indicated in dotted lines), which is equal to the resistance of the filament of the oscillating tube GE.
A receiving channel, comprisin a receiying amplifier lZt-AE, detector DE, and receiving relay RE, is shown as being associated with the receiving circuit RLE. A simlar receiving arrangement, comprising an amplifier.RACW, detector DW, and receiving relay 'RW, is shown associated witlr the receiving circuit RLW. The amplifiers RAE and RAW mav be of any well-known type: for example, vacuum tube amplifiers having the construction illustrated in Fig. 5.
The detectors, likewise, may be of any wellknown character, but are preferably vacuum tube detectors, such asillustrated at DE in Fig. 5. The receiving relay is preferably a polar'relay, and, in order that it may operate upon an alternating current. basis, the polar relay is connected to the out-put circuit of the detector through a transformer 11, as indicated in Fig. 5.
In order that the transmitting and receiving channels may be utilized for through repeating, the transmitting channel of each line is directly connected to the receiving so l - channel of. the opposite line; for example, a
conductor 12 interconnects the out-put circuit of the. receiving amplifier 'ItAlV, and the in-put circuit of the transnutting amplifier TAE; likewise, a conductor 13 di rectly connects the out-put circuit of the re-- ceiving amplifier RAE and the in-put circuit of the transmitting amplifier TAE. The manner in which the ci-rcui-t 12 is associated with the in-put circuit of the ampli Q fier TAE isindicated in Fig. 4:, and the manner in which the circuit 12-is associated with the out-putIc-ircuit of the receiving am:
, plifie r RAW will be understood from inspection of the connection of the circuit 13 to the receiving amplifier RAE, illustrated iii-Fig. 5. When the amplifiers of the transmitting and receiving channels are thus connected, the amplifier of the receiving channel works directly intothe amplifier of the transmitting channel, and the carrier sig nals will be repeated at carrier frequency.
'In order that a local subscribers loop L may be associated with the repeater apparatus for transmitting and receiving signals, a jack J is provided, in which the plug P of the loop may be inserted. The loop connection leading from jack J is balanced by means of a balancing circuit N, and three polar relays, PE, and PW, are so associated with the loop that onewinding of each relay is included in the loop connection battery lead of one polarity, while the junct the normal contact of the relay tion point 16 of the windings in the loop and balancing circuits is connected through a battery lead of the opposite-polarity over PW" and the normal contact of the 'recelving' relays. RW and RE in'series. The alternate contacts of the receiving relays are connected to battery leads of the opposite sign to that connected with the point 16. The armature of the relay PW is arranged so that when said relay is operated in response to the transmission of a signal from the loop the normal connection of battery over the contact of the receiving relays RlV and RE is opened and the normal battery connection is established directly over the armature of the relay PW independently of either re-- ceiving relay.
urther details of the apparatus will be clear from the description of the operation, which is as follows: Normally, when s1gnals are not transmitted, a carrier frequency incoming from the line MLE- passes. through the amplifier RAE and over the connection 13 to the'amplifier flAN, and thence to the" main line section MLW; similarly, a car rier frequency passes from west to east from.
the main line section MLWthrou-gh the amplifienRAlY, over the circuit 12 to the amplifier TAE, and thence to the main line sectioni MLE-. Signals may be transmitted in eitherqli'rection by interrupting the 'carrier frequency transmitted in thedesired direction. Since the circuit is intended to operate on a half duplex basis, however, signalswill in practice 'be transmitted over only one of the paths above described at a time. If signals'are transmitted over the first mentioned path byrinterrupting the carrier frequency,the detector DE will respond to the interruptions, and the polarized relay RE will shift its armature from negative battery to positive battery, "When the armature of the relay RE was connected to negative battery, since the other end of the loop was connected to positive battery, a current 'fiow through the loop wind; ings of the polar relays occurred which was twice'as great as: the current flow passing through the balancing windings, which were connected directly to ground, The effect due to the current flow in the upper windings, therefore, predominates, and the pull asserted is in such a direction as to hold the armatures of said relays in the normal position. When the armature of.v the receiving relay RE is shifted to positive battery, however, the battery connections at the opposite ends of the loop are opposing,'consequently no'current flows through the loop, and the Sounders-included therein (not shown) release their armature-s. The upper windings of the polar relays PE, PW, and PW are also deenergized, and current flows only through the lower windings of said relays. The current flow is reversed, however, from that normally flowing and consequently tends to hold the armatures of the relays against their normal contact,- so that the transmitting relay PEh'is "ineifective to transmit the signalbackito the line MLE,
from which it came, and the relay PW-is ineffective toshort-circuit the connection 13, over which the carrier signals Iare being transmitted from one line section to the other.
In a similar manner, if signals from the line MLW'are transmitted over the conductor' 12 to the line section MLE by interrupting the normally transmitted carrier frequency, the receiving relay RW responds and connects positive battery to-the point 16, so that no current flows through the loop and the sounders therein release their arma tures. Theeffect upon the polar relays PW and PW is the same as that already described.
. If it is desired to transmit signals from the loop to the two line sections, the loop may 1 be interrupted by means of a sending keynot shown). Each time the loop is opened,
quencies normally transmitted from each line section to the other are diverted to ground, and thus interrupted so far as transmission to the other transmission line is concerned. The signals originating in the loop L will therefore be transmitted to each line sectionas interruptions in the carrier frequency. The relay PW, in shifting its armature to its alternate contact, connects negative battery to the point 16 directly over said contact, and independently of the armatures of the receiving relays RE and RW, so that said relays are ineffective to transmit si-gnalsto the loop while signals are being transmitted from t e loop.
A break signal may be transmitted from the loop when signals are being received from either line section by holding open the loop by means of a sending key. The opening of the loop causes the closing of the short circuit connections 14 and 15 in the manner previously described, and therefore the carrier frequency transmitted from each line section to the other will be interrupted during the continuance of the break signal. The effect of the break signal at the sending station, which may be assumed to be similar to that illustrated in Fig. 1, may be underbe transmitted over the through repeater stood from the eifect of a break signal received by the loop L. If a break signal comes in from the line section ML'W,'the receiving relay RW shifts'its armature and connects positive battery to the point 16. As soon as the armature of the relay PW assumes its normal position, which will occur when the loop is closed by the transmission of the space signal, no current flow occurs through the upper windings of the relays PE, PW and PW, and the current flow through the lower windings is in such a direction as to hold their armatures against their normal contacts. The operator, in opening and closing the loop for further transmission of signals, will observe that the local sounder does not follow the sending key, and will therefore be apprised that a break signal has been received.
Fig. 2 illustrates a similar arrangement adapted to be operated upon a full duplex basis. The through repeater connections are the same as in Fig. 1. In this instance,
however, signals wili in practice he simultaneously transmitted in both directions by interrupting the normally transmitted carrier frequency. This involves the provision of an additional subscribers loop, so that signals may be received and transmitted simultaneously from the subscribers station. One of the loops is arranged to receive through signals transmitted from to that shown in Fig; 1, but in this instance the normal battery connection to the point 16 extends onl over the contact of the receiving relay W, and is entirely independ- 'ent of the receiving relay RE. Polar relays PE'and PE are ascociated with the loop LE, said relays havingtheir upper windings in the loop and the lower WHldings in the balancing circuit MNE. A connection extends fromthe junction point 17 of the polar relay windings over the normal contact of the armature of the polar relay PE, and over the normalcontact of the receiving relayRE to negative battery. Positive battery is connected to the alternate contact of the receiving relay RE,.and the connection is such that when the armature of the polar relay PE is shifted from its normal position the battery connections controlled by the relay RE are opened, and an independent connection to negative battery is closed. a
The operation is as follows: Signals will channel from the line section MLE to the line section MLW as described in connec-- tion withFig. 1. Each time the frequency is interrupted the receiving relay RE respondand shifts its armature from negative battery to positive battery, so that the battery connections at each end of the loop LE are -mutually opposing. No current flows through the loop, therefore, and sounders in the loop respond. The upper windings of the polar relays PE and PE are deenergized' but the current flow through the lower windings isin such a directionas to hold the armatures of said relays against their normal contacts, and the signal is thereby prevented from being transmitted back to the line section MLE. Signals may be transmitted from the loop LE by opening and closing the same. Each time the loop is'opened. the upper windings of the relays PE and PE are deenergized, and the lower windings become effective to shift their armatures to their alternate contacts. The armature of the relay PE, when shifted, closes'shortcircuit connections 14,
whereby the carrier frequently transmitted simultaneously.
from west to east over the circuit 12 may be interrupted, and signals transmitted over the line sections MLE. The armature of,
the polar relay PE is shifted at the same time, and opens the battery circuit controlled by the receiving relay RE, and connects the negative battery to point '17 independent of the saidrelay. The receiving relay is therefore ineffective, to transmit signals to the loop when signals are being sent from the loop.
The voperation of the lOOp 'withtre spect to receiving signals transmitted from west to east and with respect to the trans-1 mission of signals from the loop west will l1c readily-understood from the operations above. The details of this featureof the operation 'need not, therefore, be further considered.
It will .be seen from the description of Fig. 2 that While the carrier channels are arranged to be operated full duplex, eachof the subscribers loops LE-and LW'is operated on a half duplex basis, as the same loop is used both for transmitting and receiving, the t wo operations cannot take place F igi'3i'l'li1strates an arrangement, how- ....e.y:er., in which not only the carrier channels i This involves the 'are'operated full duplex, but the loops are "also arranged to be operated full duplex. provision of four loops, :the loop RLE receiving signals transmitted from east to West, the loop RLW receiving signals transmitted fromv west to east, the
loop TLE transmitting signals east, and the loop TLWV transmitting signals west. As an additional feature, a switch SS is pro- Vided whereby the transmitting loops 'TLE andTLW may be connected together, so. that'.si -gnals may be transmitted both eastand' west from the loop by operating a single key. The receiving relays RE and-RW are arrangedto merely open and close the loops RLE and RUW respectively. In the normal arrangement of the 'loopsaTLE and arranged as indica edf balancing;circu i TNE and T'NW are. pr0v.-ided for the two loops, said balancing circuits being so arranged that, duetothe potential of the batteries connected to thejunctionpoints 16 and '17 of the loops and b'alancing'circuits, a greater current fiows through the loop than flows through the balancing circuit. The windings of polar relays PE and PW i are arranged so that the upper windings are in the loop circuits and the lower wind- .the line section signals.
I the frequency transmitted exam 1e, the;
as Figs. 1 and 2. The battery connections to the points 16 and 17 are of opposite signg'so that ifthe loops TLE and TLl/V be clearly connected by means of the switch SS, a greater current will flow through the serial loop thus obtained thanthrough the balancing circuits, due to the fact that the batteries arelseries aiding. With thecir- "cuit in this condition, signals may be simultaneously transmitted from the loopboth to the east and to the west by operating either the key KB or the key KW.
The operation is as follows: transmitted .from the line section the-line section MLlV through the repeater connection 13 willf'operate through the detector'D to respond, thereby opening and closing the" loop circuit RLE so that the receiving sounder ltSE records the signal. In a sim-.
ilar manner carriersi'gnals' transmitted from MLVV to the line section MLE .over the repeater connection 12 cause the receiving relay RW to respond, thereby opening and closing the loop so thatthe receiving sounder RSW records th With the switch SS in.normal position as shown in the drawing, loop-s TLE and TLVVai'e both grounded and signalsmay be simultaneously nipulating keys KE the'loop TLE is opened, the upper Winding of the polar relay PE is deenergized, and the lower winding thereof becomes effeo-' tivetoshift its armature to close the short circuit ,conection 14, thereby interrupting over the conductor 12to the line section NLLW. Similarly, the opening of the loop the upper winding of the polar relay PW, so that the lower winding becomes effective to shift the armature of the relay and close the short circuit connection, 15, thereby interrupting the carrier frequency normally transmitted over the circuit 13 to the main line sectiOnMLWJ Signals MLE to E to cause the receiving relay RE inc sent from each'loop by'mav and KW. Each time-'- TLW deenergizes If the switchSS is shifted to connect the loops TLE and TLW in series, signals may be simultaneously transmitted both east and west by. the same key. If the serial loop thus formed; isope'ned by the key KE, for
lays E and are deenergized, and the upper windings of both re can armature of both relays, thereby interrupting the normal carrier frequency transmitted in each direction from one line section to the other. Consequently, the signals from the serial loop are transmitted to the line section MLE as interruptions of the carrier frequency transmitted from MLVV to MLE, while the similar interruptions of the loop are transmitted to the line MLW as in-' by theoscillator, and this frequency may be interrupted by the short circuit connections 14: and 15, which will extend over a portion of the conductors 12 and 13 to the grid circuits of the transmitting amplifiers. The operations of sending and receiving with the circuits thus altered will be obvious from the operations already described, and need not be further discussed;
It will be obvious .that the general principles herein described may be embodied in -many other organizations widely differentfrom those illustrated, without departing from the spirit of the invention as, defined in the following claims.
What is claimedis:
1. In a signaling system, two transmission line sections over which carrier currents may be transmitted, a carrie'rrepeater arrangement for interconnecting said sections, said repeater arrangement comprising carrier transmitting channels and carrier receiving channels associated with each line section, means for interconnecting the carrier receiving channel of each line section with the carrier transmitting channel of the opposite line section, a low frequency telegraph circuit, a balancing circuit therefor, a polar relay arrangement having windings in said telegraph circuit and balancing circuit, means whereby said polar relay may control the transmission of carrier.
currents from at least one of said carrier transmittting channels to the corresponding line section, a receiving relay associatedwith at least one of said carrier receiving channels, a source of current connected to the junction point of the windings of said polar' relay arrangement over one contact of said receiving relay, a second source connected to the opposite end ofsaid telegraph circuit, said second source being so poled as to be mutually aiding with respect to said first source, a third source connected to another contact of said receiving relay, said third source being so poled that when the armature of the receiving relay is shifted,
mutually opposing sources will be connected to said telegraph circuit, and means whereby when said polar relay arrangement is opjerated in response to signals received over said telegraph circuit, said first mentioned source will be connected to the junction pointof the windin s of said polar relay arrangement indepen' ently of said receiving relay.
2. In a signaling system, two transmission line sections over which carrier currents may be transmitted, a carrier repeater arrangement for interconnecting the ends of said line sections, said carrier repeater arrangement comprising carrier transmitting channels and carrier receiving channels associated with each line section, means for interconnecting the carrier receiving channel associated with each line section with the carrier transmitting channel associated with the opposite line section, a low frequency telegraph circuit, a balancing circuit there-.
for, a polar relay arrangement having windings in said telegraph circuit and said balancing circuit, said polar relay arrangement controlling the transmission of. carrier currents from both transmitting channels to the corresponding line sections, receiving relays associated with each carrier receiving channel, a source of current connected with the junction point of the windings of said polar relay arrangement oyer-a contact of each of said receiving relays in series, a second source of current connected to the opposite end of said telegraph circuit, said second source of curent being so poled as to be mutually aiding with respect to said first source, and a third source connected to other contacts of each of said receiving relays, said third source being so poled that when the armature of either receiving relay is shifted, mutually opposed sources are connected to opposite ends of said telegraph circuit.
3. In a signaling system, two transmission line sections over which carrier currents may be transmitted, a carrier repeater arrangementfor interconnecting the ends, of said line sections, said carrier repeater arrangement comprising carrier transmitting and carrier receiving channels associated with each line section, means for connecting the carrier receiving channel associated with each line section ith the carrier transmitting channel associated with the opposite line section, a low frequency telegraph circuit, a balancing circuit therefor, a po ar relay arrangement having windings in said telegraph circuit and said balancing circuit,
said polar 'relay arrangement controlling.
- l tually' aiding with respect to said first source, and a third source connected to other contacts of each of said receiving relays, said third source being so poled that when the armature of either receiving relay is shifted, mutually. opposed sources are connected to opposite ends of said telegraph circuit, and means controlled by said polar relay arrangement whereby said first mentioned source may be connected to the junction point ofthe windings of said polar re-.
lay arrangement independently ofthe contacts of either receiving relay.
4. In a signaling system, two transmissionv line sections over which carrier currents may be transmitted, a carrier 1 repeater arran ement for interconnecting the endsof said line sections, said repeater arrangement comprising carrier transmitting channels and carrier receiving channelsassoclated wlth each ,35 line section, means for interconnecting the carrier receiving channel of eachline section with the carriertransmitting channel of the opposite line section, a low frequency telegraph loop circuit, a pair of transmitting 4 polar relays each having loop vwindings and balancing windings, fthe loop windings being a q mutually in series in said loop circuit, sai polar relays controlling the transmission of carrier currentsfrom the transmitting channels to the correspondin line sections, mu-
tually aiding sources 0 current connected to opposite ends of said loop circuit, and means associated with said loop whereby both polar transmitting relays may be operated jointly to transmit signals from said loop over both line sections simultaneously.
5. In a signaling system, a' pair of trans-' mission line sections over which carrier cur rents may be transmitted, a carrier repeater apparatus for interconnecting the ends of said line sections, said repeater apparatus comprising carrier transmittlng channels and carrier receiving channels associated i with each-"line section, meansgfor interconnecting the carrier receiving channel ofeach line section with the carrier transmitting channel of thenopposite line section, a low frequency telegraph circuit, abalanclng circuit therefor, a pair of polar relays each having windings in the telegraph circuit and 1n the balancing circuit, thewindings of said polar relays in said telegraph circuit being mutually in series and the wind ings of said polar relays in'the balancing circuit being mutually in series, means op 'erated by, at least 'one of said polar relays for controlllng the transmission of carrier currents from one of said carrier transmitter channels to a line section, a receiving relay associated with at least one of said carrierreceiving-channels, a source of current connected to the junction point of the'windings of said polar relays over one contact of said receivingv relay, a second souroeof current connected to the opposite end of'said telegraph circuit, said second source being so poled asto be mutually widing with respect to the first source, and a, third source, connected to another contact of saidreceiving relay,-said third source fi being, of opposite polarity from said first source, and means controlled by one of said polar relays whereby when signals are transmitted to the polar relays over said low freuency telegraph circuit, said first nientloned source will'be connected to the junc- 9 tion point] of the windings of said relays inde endently of said receiving relay.
n testimony whereof, I have signed my name to this specification this 18th day of October, 1920. I I
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