US1608509A - Carrier-wave signaling system - Google Patents

Description

Nor. 30 1926.

J. s. JAMMER CRRIER WAVE SIGNALING SYSTEM Fi1ed D90. 29, 1920 Jacok 5 Jammer Patentecl Nov. 3,

INCOBPORATED, OF NEW' YORK, II.

Appliczition fi1ed December lhis invention relates t carrier wave signaling systems and more particularly to sucl1 systems wherein two-way operation is provided over two-way channels between an ordinary telephone line and a carrier wave transmission medium such as the natural media used in radio Communications, an ordinary telephone er telegraph transmission line, 01 a power transmission line.

In systcms of this general type it is customary to have an ordinary lOW frequency telephone line normally connected to a twoway channel of a carrier wave terminal sta tion. 'lho low frequenc v line is connected conjugately through a balariced transformer to the transmitting and receivinp; circuits of the tw0-way channel. F0r testing or other purposes, it is often necessar v to disconnect the low frequency line from the carrier terminal channel, and for this purpose a jack 0r contact arrangement is insertecl between the balanced transformer and the low trequency line. With sucl1 an arrangement, unless soms precaution is taken, the two way channe] will sing due to the unloalancing of the balanced transformer when the low freouency line is disconnected.

It is an object of this invent-ion to prevent tle carrier cl1annel trom singine or otherwise 1nis-iunctioninsr due to this discon nection of the low frequenc; line. A tea ture of the invention is a jack and relay arrangement rvhereb v this result may be accomplished. Another feature is the accomplishment of this result b v short-circuiting the speech input circuit of the modulator. A turther object is to provide an arrangement or short-circuiting the modulator which will function onl v when no substitute line or equivalent apnaratus is connected in place of the normally connected low fre quency line.

In ons emhodiment of the i1wention these objects are accomplished hy providing a relav. through a normally open contact of Which the speech input circuit of a.modu lator mar loe shortcircuited when desired. A low frequency line is terminated in a pair of jacks at the carrier terminal station. The 10W frequency terminal of the two-way carrier chan1iel at the same station is also terminated in a pair of jacks. These two pairs of jacks are normally s0 connectecl together as to form a continuous transmission circuit between the low freone two-way quency line and the two-way carrier chann el. For call signaling tl1e modulator short crrcuiting relay is actuated. For ether purposes, hereinatter to be dcscribed, tliis jack arrangement permits the operation of the modulator short-circuiting relay when a plug is inse ted in the line jacks providing thc carrier terminal jacks are normal.

This inventiou will be more clearly undcrstood trom a detailed description of one cmbodimcntthereot and li reterence to the accompanying drawing. 'lhe clrawing illustrates a multiplex carrier telephone sy tem showinp; in some detail one complete two-waycarrier channel. Another similar channel is merely indicated.

@ne terminal station 0lllf is shown, it being understood th at tl1erc is a similar distant cooperating station (notshown). 'lwo-way channels of the station shown coopcrate with correspcnding two-way cl1annels of the distant station. The transmitting circuit of cl1annel in turn cooperatcs With the receiv1ng circuit of the cooperating distant cl1annel, and vice versa.

Tlie terminal station iilustrated in t-lie drawing comprises a two-way carrier channel CH transmittingr circuit TC ancl a receiving circuit for channel CH are connected to a common line ML through a balanced transtormer 5. These circuits are also connected to a two-wire low frequency line 2? through a 10W frequency balanced transtormer l. Balanced transtormers 4: and 5 have a high requenc net HFN and a lou frequency net Lllf l respectively connected to their line windincs. Tlie opposite terminals 01 the line windings of balanced transformer i are connected tl1rough the normally closed back contacts of iiiiging relay 6 to carrier terminal. jacks 7, A telephone station A is connected to a low frequency line L which terminates in a pair of jacks 8, 8. Jacks 7, 7 and 8, 8 are connected together loy concluctors 9. so that, normally. a continuous transmission circuit extends trom station A over line L tl1rough jacks 8. 8 conductors 9 jacks 7, tlnougli channel CH to the common line l'illl].

Transmitting circuit TC comprises a source of carrier Waies modulator llil. and modulator hand filter ll IBF ii. speech input circuit tor the modulator M compriscs concluctors 10 wliicli connected betweon the series winding of the balanced traittormer 1 and the modulator M. '1he receiving circuit RC co1nprises a detector band filter DBF a detector D, a detector amplifier DA, a speech frequency transtormer 11, and a low pass filter LPF connected to the bridge circuit of balanced transformer 4. For signaling purpo-ses a signaling detector SD may be connected to the output circuit of the detector amplifier DA to proxj-de signaling energy tor relay 12.

Modulator hand filter MBF and detector band filter DBF are each adapted to pass a broad band of requencies and may be ot the general type described in Patents Nos. 1,227,113 and 1,227,111 to G. A. Camploell dated May 22, 1917. The constants of these filters are so chosen as to pass the particular range of trequencies, which are being used tor the particular receiving or trausmitting; circuit. In general the several receiving and transmittingcicuits will employ distinctive hands of irequencies.

The 10W pass filter LPF is also ot the general type described in the above mentioned Camploell patents and is adapted to suppress currents having frequencies above the highest essential frequency o;t voice currents and to transmit with suhstantially negligible attenuation currents of the highest essential voice fiequency and of all lower trequencies.

The source of carrier waves O, the modulator M, the detector D, the detector am'plifier DA and the signal detector SD may be of any suitable construction, b-ut preterahly each is of the wellknown three electrode thermionic va uum tube type.

Fo-r transmitting call signals to a distant station, relays 13 and 14. are provided. For receiving call signals from a distant station, signaling detector SD, relays 12, 6, and the lower winding of relay 3 are provided.

A second two-way channel, CH is indicated,and as shovvn is also connected to the common line ML through the loalanced transforrner 5. On the low requency side it terminates ina pair ot jacks 15, 15. A. second low requency telephone terminal station B is associated through a 10W trequency line L with a pair of jacks 16, 16 located at the carrier terminal station. These jacks are likewise connected together to torm a continuous circuit trom telephone station B over low requency line L through jacks 16, 16, jacks 15, 15, twoway carrier channel CH2, and the balanced transformer 5 to the main line ML.

A modulator hand filter MBF and a detector band filter DBF are connected respectively in the transmitting and receving circuit-s ot two-way channel CH These band filters are of the same general type as the corresponding filters in channel CH differing only in their constants in order to provide selectivity between thesereral carriet channels. As shown, the modulator hand filters are connectved in series with each other in a manner which is Well known and described in United States Patent No. 1,428,155, September 5, 1922, issued to: L.. E. Espensclried and= H. A. rrel to form a common transmitting circuit. Similarly the detector hand filters are connected in series according to the same principle to form a common receiving circuit.

T he block T represents a test set terminating in a pair of plugs 17, 17 whiclr. are adapted to connect with aairs or"" jacks as illustrated. Block TS may illustrate a tele phone set adapted for use with either lines L and L or with twoway carrier channel's CH and CH Sucli telephone set nra=y terminate in a pair of plugs 18, 18 similiar to tliose previously described. A. patchi-ng oord" is also shown comprising the conductors 1.9 terminating at one end in a pair of plugs 20, 20 and at the other in a pair of plugs 21, 21. These pairs of plugs are likewise adapted te cooperate with the pairs of jacks as illustra-ted.

ccording to this invention, relay3 at its upper normally open back contact is adapted upon ene-rgization to short-circuit the speech input circuit 10 of the modulator by closing the circuit through conductors 22. Relay 3 may be energized by current in its upper winding, a circuit tor which may be traced trom ground through battery 23, the upper winding of relay 3, normally closed upper contact ofupper jack 7, conductor 21, nor- 1nally open contact of upper jack 8 to ground. Relay 3 may also be energized by current in its lower winding, a circuit tor which may be traced trom groundthrough battery 23, lower winding of relay 3, normally open back contact of relay 12 to ground. Tliis last traced circuit is provided to pre vent singing in the two-way channel CH while call signals are being received from a distant cooperating station.

The operation of the system under several conditions will now be descriloed.

.The operation will first be descriloed in connection with call signaling or ringing. VVith the connectionsas shown, it Will he assumed that station A desires to call a distant cooperatin-g station (not shown). The operator at station A Will impress ringing current in a well-known manner on the line L which Will traverse 1ine L jacks 8, 8, conductors 9, jacks 7, 7, normal1y closed back contacts of relay 6, lower closed contact of relay 3, and windings of relay 13. Relay 13 will respond theret-o by vibrating at the frequency of the ringing current, and cause the deenergization of relay 14 by opening its normally closed energizing circuit at the normallyclosed back contact of relay 13. The

deenergization ot relay 1t places a shortcircut upon the oscillator output circuit by closing a circuit to ground through its normally open front contact now closed. In the normal operation of the system, the oscillator O causes a continuous flow of carrier waves to the main line ML through the modulator M, modulator band filter. MBF and loalanced transformer 5. The short-cir cuiting of the oscillator O interrupts tl1is normal flow of carrier waves as long as ringing current is impressed upon the low frequency line L The action at the cooperating distant sta tion will now loe described in connection with the receiving circuit RC of channel CII Carrier waves transmitted from the distant station, which are normally present on the COII1II1OI1 line ML are impressed upon the signaling detector SD from the balanced transformer 5, detector band filter DBF detector D, and detector amplifier DA. The signaling detector SD functions to cause a flow of unidirectional current in relay 12 to normally hold open its back contact. Carrier waves are prevented fro1n being impressed upon the bridge circuit of balanced transformer 4 by means of the 10W pass filter LPF.

During the time when the train of car rier waves is interrupted at the distant transmitting station as just described, relay 12 is deenergized. Thereupon relays 3 and 6 are actuated by current rom batteries 23 and 25 respectively, a circuit trom ground through battery 23, lower winding of relay 3 and back contact of relay 12 (now closed) to ground being completed for relay 3 and another circuit trom ground, through battery 25, winding of relay 6, the same back contact of relay 12 (now closed) to ground for relay 6. Relay 3 Which is quick acting places a short-circuit tlirough conductors 22 upon the modulator input circuit 10 to prevent modulating current trom entering the modulator therefrom. Relay 6, which is somewhat slower to act disconnects the 10W frequency terminal jacks 7, 7 from the carrier channel CH and connects a source of ringing current 26 to the low ductors 27. Ringing current is therefore impressed upon the 10W frequency line L to operate a signaling device (not shown) at station A. When the 10W frequency con ductors 27 are disconnected from the line windings of balanced transformer 41, carrier channel CH is unloalancecl at the transformer 4, and singing would result were it not for the short-circuiting of the modulator input circuit 10. ringng interval, carrier waves from the distant station are again impressed upon the signaling detector SD to energize the relay 12 Which allows relays 6 and 3 to loeconie deenergized, and the armatures to fall back to tlieir normal positions. Rclay 6 is more quick to release than relay 3. It thereore connects the line L to the carrier channel CH before the shortcircuit is removed frequency con- At the close of the from the modulator input circuit 10, thereby guarding the circuit against 'alse operation due to charging current in the line L discharging through the modulator M and so into the carrier system as a whole. With the circuit as shown, such discliarge, if present, takes place tl1rough the short-circuiting conductors 22 and the energy thereof expends itse1f harmlessly in the resistance of the circuit.

In another situation now to be explained, the carrier channel OI-I is unloalanced and the modulator input circuit 10 is a ain shortcircuited to prevent singing anc misfunctioning of the system. Such a situation arises when the low frequency line L is disconnected from the carrier channel CH by the insertion of plugs such as 17, 17 into jacks 8, 8 for testing purposes or the like.

When the plugs 17 17 are insertecl in the jacks 8, 8 the conductors 9 are disconnected trom the line L at the normally closed contacts of the jacks 8, 8. By the same opera tion a circuit through the upper winding of relay 3 is completed. This circuit extends trom ground, through battery 23, upper winding of rela y 3, conductor 28, upper normally closed contact of upper jack 7, con ductor 24, normally open contact of upper jack 8 (now closed) to ground. Relay 3, is actuated, and a short-circuit as l1ereinbefore descriloed is placed upon the modulator input circuit 10 to prevent singing due to the unloalancing of channel CH Still another situation may arise. VVhile the line L is being used for test purposes or the like, it may be desiralole to connect another low frequency line such as L to the carrier channel CH whereloy a subscriber at station B on line L may communicate over channel CH and it cooperating dis tant channel. To permit of this, jacks 7, 7 and 16, 16 are connected together by a patching oord 19. Plugs 20, 20 are nserted into jacks 7,7 and plugs 21, 21 are inserted into jacks 16, 16. VVit-h plugs 17, 17 in jacks 8, 8 as hereinbefore describecl, channel CH cannot function due to the shortcircuit of the modulator input circuit 10. The insertion of plugs 20, 20 into jacks 7, 7, it Will be noted, removes this short-circuit by opening the en'ergizing circuit of relay 3 through its upper winding at the upper normally closed contact (now open) of upper jack 7. Tlius the carrier channel CH is restored to normal, and it can function exactly the same as though line L were connected to it insteacl of line L It should be noted that the insertion of plup;s 21, 21 in jacks 16, 16 Will disable channel CH by placing a short-circuit across the modulator input of that channel in the same manner as described in connection with channel CH whcn plugs 17, 17 are inserted in jacks 8, 8.

With ihecar1ier terininai apparatus anti 10W frequency iines in use as just ciescriiceci, arrier channei CH may be restored te operating cenciition, by the insertion of piugs 18, 18 int0 jacks 15, 15. By this connection channei CH niay be useci in connectien with apparatus '1S or taiking purposes, testing purposes 01 the like.

Other combinations than those ciescribeci wiii be evident to those skiiieci in the art, but it Wiii be noted that in every case, when the ieaiance of a tw0-way channei is tiestrcyeci, cieieterious efects such as singing are preventeci by 1neans independent 0 the i3aiance of the channei. It shouici also be notcci that, whiie ti1e channei is thus dis abieci, it maybe restoreci t0 nern1ai operating conciition by the connection of suitabie apparatus to the channei terminai jacks.

i Vhiie the citaiieci description of the invention has been confineci te its en1bocii1nent in a 1nuitipiex carrier wave signaiing systen1, ether embeciixnents there0f W'iii i0e evident t0 these skiiieci in the art anti the invention is to be iimiteci oniy by the scope of the appencieci claims.

1Vhat is ciain1ed is:

1. A co1nrnon transn1ission iine, a twe- Way c0nnnunication circuit connecteci thereto and having an inco1ning channei and an circuits each aciapteci te be connecteci t0 said iine over saici communication circuit, 2111(i 1neans f0r shortcircuiting saici outgoing3; channei t0 prevent singing in the connnunicationcircuit when none of saici signaiing circuits are connecteci thereto.

2. A signaitransrnission circuit, a tweway communication channel connecteci tiierete anti having an incorning and an ontgoing channei, ter1ninating 1neans for saici transmission circuit, a sec0nci transmission circuit, ter1ninating 1neans for said seconri transmission circuit, anti means under the control of botirof saici ter1ninating 1neans te ciisabie saici out-going channei.

3. In a carrier wave signaiing system. a

two-way carrier channei, terminating 1neans 0r saici channei, a 10W frequency iine, ter- 1ninating 1neans f0r saici iine, n1eans te connect said two ter1ninating ineans together te form a continuous transxnission circuit, anti 1neans uncier the controiof iooth saici terminating 1neans to ciisabie saici channei for twc-way communication.

1. In a signaiing system, signai wave modifying 1neans, a sigriai originating cir cuit, a contact arrangement ccnnecteri te saici signai wave mociifying n1eans, a second contact arrangementconnecteci t0 saici signai originating circuit, a connection between aici contact arrangements te operabiy associate saici signai wave modifying means with saici signai originating circuit, 1neans centroiieci by the operation of saici second contact arrangement t0 ciisabie sairi signai Wave modifying 1neans, anci 1neans controiieci by the operation of saici first contact arrangement to prevent tiie ciisabiingethe signai ware mcciifying 1neans.

5. in a carrier wave signaiing systen1, a two-way carrier channei, a pair of jacks 10r terminating saici channei, a 10W requency line, pair of jacks or terminating said iine,

conductors connecting saici 1ine jacks anci channei jacks toget-her t0 forni a coniinnous transmission circuit, anti a reiay uncier the controi of both saici iine 21I1Ci Channei ter1ni nat-ing jacks te ciisabie saici channei 0r twoway communication.

6. In a signaiing syste1n, signai wave meciifyingr 1neans, a signai originating circuit, a pair 0 jacks connecteci tesaici WIVG 1nociiiying means, a sec0nci pair of jacks conne ieti te saici signai originating circuit, conciuctors connecteci te boti of sairipairs of jacks t0 operabiy asscciate saici sigriai wave medityinq n1eans witi1 saici signai originating circuit, a pair 0 piugs, 1neans controiieci by the insertion of saici piu9;s into the jacks connecteci t0 saici signai originating circuit te ciisabie saici signai waje mociifying 1neans a seconci pair of piugs, anti means ccntroiied by tie 1nsertion 0 sarci seconci pair of piugs into the jacks connecteci t0 saici signai wave 1nociifying rneans to prevent 'the ciisaiciing of the signai wave- 1nociifying n1eans.

7. In a signaiing system, a 10W frequency iine, a two-way carrier channei comprising an outgoing anci an incmning branci1 connected in ccnjugate reiation with saici iine, 1neans at a piuraiity of points f0r disconnecting said iine rr01n saici channei, an i 1neans operateci in conjuncci0n with the operation of each of saici disconnecting 1neans t0 ciisaioie saici outgoing channei.

8. A combination in accorciance with ciai1n 7 in which one of saici ciisconnectinp 1neans is aciapteci te ciisconnect the 10W frequency line from the carrier channei anti t0 appiy te saici iine currents of signaiing requency;

9. A two-way connnunication system in ciuciing a 10w frequency iine, a two-way carrier hannei c01nprising an outgoing anti an inco1ning branch connecteci in conjugate re iation with saici iine, said cutgoing carrier b-ranch inciuciing a source 0 carrier frequency waves llCi a 1nociuiator therefor, n1eans iocateri at a piuraiity of pcinis in saici iine for ciisconnecting saici iine 'fr0n1 saici carrier channe-i. a reiay aciapted te short circuit saii modulator, anti naeans' 0r operating saici reiay in conjunction with the 0peration of any one 0 sa1ci ci1sconnect1ng 1neans.

In witness whereof, I h-ereunto subscriice 1ny name this 24th ciay 01 December A. D., 1920.

JACOB s. JAMMER

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