US1707997A - Telegraph system - Google Patents

Description

AWE?! Q, 1929. R. B. SHANCK mm w TELEGIIRAPH SYSTEM Filed Aug. 23, 1927 III!!! in, mi 3,

m I/L m INVENTOR.

Patented Apr. 9, 12929.

nearer BOY B. SHANCK, OF FLUSHING, NEW' YORK, ASSIGNOR TO AMERICAN TELEPHONE LAND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TELEGRAPH SYSTEM.

Application filed August 23, 1927. Serial No. 214,905.

This invention relates to telegraph signaling systems, and particularly to the application of counter-electromotive forces to such systems in order to maintain a fixed relationship between the durations of the marking and of the spacing impulses in order to reduce or minimize distortion.

In this invention, counter-electromotive forces will be provided at telegraph subscribers stations for the purpose of improving the transmission in order to overcome the objectionable distortion of signals due to the inequality of the durations of the marking and spacing impulses. In former telegraph systems, considerable distortion ofthe signals is experienced in operating the local telegraph circuits by what is known as the open-and-close method. In the latter method of operation, the current at closing, i. e., at the marking impulse, usually builds up to a steady value exponentially, the time required for the current to reach the steady value depending upon the time constant of the circuit. The time constant may be looked upon as a measure of the slowness or fastness with which the current reaches its steady value. The greater the number of souneers or relays or other electromagnetic devices in a circuit, the slower the circuit usually becomes tor signal transmission and, therefore, the more grat'lual is the increase in current when the circuit is closed. However, when the circuit is opened, the current drops immediate- 1y to zero. Accordingly, there is a tendency toward the shortening of the marking impulse at the telegraph receiving instrument. Thus, the spacing signal may be considerably longer than the marking signal.

The objects and features of this invention will become apparent from the following detailed description thereof, when read in connection with the accompanying drawing, in which Figure 1 represents a portion of a telegraph system in which counter-electromotive force cells are connected across a transmitting key therein; Fig. 2 represents a similar telegraph arrangement which avoids short-circuiting the source of counter-electromotive force, and Figs. 3 and 4- represent curves characteristic of the current flowing through the winding of a telegraph sounder.

Referring to Fig. 1 oi the drawing, a telegraph sounder S shown, having an Ftl'nlitf wh :ti as between mark spac ng contacts as the currentthrough 1ts winding changes trom one value to another. The winding of sounder S 1s connected in series relationship with a battery B, through a parallel circuit comprising a battery B and a resistance R, as one of the branches, and a key K as the other of the branches. The winding of the sounder S is also in series with the upper windings TV, and V2 of a receivlng relay RR and of a break relay BR, re spectively. Nindings WV, and V], are also serially connected to an armature T of a transmitting relay (the winding or windings of which are not shown). As the armature T of the transmitting relay moves back and forth between its contacts M and S, either battery B or battery 13,, of opposite polarities, may be connected thereto. Lower windings V7, and N of the receiving relay RR and of the break relay BR, respectively, are also connected in a series circuit with a resistance R and with the armature T of the transmitting relay.

'lhe magnetlzations of wmdings'VV and vW, and of windings V andVV, control the movements o't the armatures U and V between the marking and spacing contacts M and S in the receiving relay RR and in the break relay BR, respectively, the armature of the receiving relay RR operating a receivmg circuit not shown). The windings W, and VJ, and the windingsW, and W, are

preferably alike in all respects and are energized by similar currents so that armatures U and V of these relays may move back and forth in synchronism. It is to be observed that when the armature V closes its spacing contact S, marking battery B will be connected to windings W, and TV, and to windings WV, and V even though the armature T of the transmitting relay may close its associated spacing contact S. This is so except, however when this armature, i. e., armature T, is traveling between its contacts. The el ifect upon the system due to armature T not touching either of its contacts is negligible for practical purposes.

Marking and spacing signals may be transmitted over the loop to the sounder S by the operation of armature T of the transmitting relay. When armature T closes-its marking contact M, key K at the other end of the loop remaining l 1, current wi l then flow through i. A l

B these windings being so poled as to produce spacing eliects upon their respective armatures. At the same time, battery B, will be in series with battery 13,, and accordingly, a conrparatively large current will flow through windings W ant N of the receiving relay RR and of the br ak relay BR, respectively. Under these operating conditions, the magnitude of the current through windings and l V may be substantially twice as great as the magnitude of the current through windings WV, and W and the former current will sutiiciently energize windings V and W so as to overcome the spacing ell'ect produced by windings W 3 and Therefore, armaturcs U and V of the receiving and break relays, respectively, will close their marking contacts M. A marking signal will also be noted at the sounder S.

When the armature '1 ot the transmitting relay closes its spacing contacts, the current through windings W and N, will he of a magnitude the same as heretofore, but will be oppositely direct-ed due to the connection of the oppositely poled battery B Accordingly, the connection of battery ll, "to windings W and V], will produce marking effects on the respective armatures. Moreover, battery B, will be connetced in series with battery 13, through the winding of the sounder S and through the windings N and of the relays and BR, respectively. "Since batteries B, and ll arc 01 substantially equal potentials and of opposite polarity, no current will flow through the latter windings. Accordingly, armatures U and V of the relays RR and BB, respectively, will .remain in their positions against their marking contacts M, while a spacing signal will be noted at sounder S. 'llhus, as armature T moves back and forth bet-ween its contacts M and S, marking and spacing signals are noted at the sounder S, while the armatures U and V of relays RR and BR, re spectively, remain biased against their marking contacts.

Telegraph key K may be operated to transmit marking and spacing signals over the loop circuit to relays and Bit. It is to be particularly noted that battery B, and resistance R, shunt key. Also, when key K is open, battery B is in series with battery B as well as with the winding 01 sounder S. During the transmission of n'iarking and spacing signals over the loop circuit by the operation of key K, the armature 'l of the transmitting relay will ordinarily be niaintained against its marking contact M. It battery B be considered a battery having a potential substantially twice that of battery 1%,, then when key K is opened, substantially no current will flow through windings W and W of the relays RR and ER, respectively, While a normal current will flow through windings Vi and W of these relays from battery 13,, the latter windings being so poled as to produce spacing effects upon the armatures oi the respective relays. Therefore, armatures U and V will close their spacing contacts S. When key K becomes closcd, the effect of battery B is eliminated, and battery B is then connected in series with battery and aids battery B, in sending a comparatively large current through windings 'TW, and V Clearly, the joint eli'ect 01' the currents through windings V], and W and windings N, and Vi will move armaturos U and V of the respective relays to their marking contacts M. Thus, it will be apparent that as key K is opened and closed, spacing and marking signals will be noted at the sounder S, while the armatures U and V of relays ltltand 13R, respectively, willalternately move between their spacing and marking contacts.

Fig. 1 illustrates the principles of the invention as applied to a terminal telegraph repeater system employing an upset polar loop circuit. Fig. 2 shows the princiles of this invention applied to two tori type repeaters connected so as to form an intermediate repeater in which a loop circuit also is user. The arrangement shown in Fig. 1 discloses a group of counter-electromotive force cells B, which are connected across the transmitting key K, and the electromotive force of these cells is just sutiicient to bring the current through the winding of the sounder S as well as through windings and W to Zero when key K is open. Yet, when key K is closed, battery 13, is short-circuited which may be undesirable in practice. In Fig. 2, battery B is connected in series with the-sounderS when key K is opened, thereby preventing the source of counterelectromot-ive force from being sh01'tcircuite(. p

In Fig. 2, armatures T, and '1", may move back and forth between marking and spacing batteries M and S, batteries 13,, and B being normally connected to the marking contacts M, while batteries B and B are connected to spacing contacts S. The wind ing of sounder S is connected in a series circuit with windings l V, and V], of the receiving relay RR, and 01" the break relay BR, respectively, and is also connected in the same series circuit with windings N, and W of the receiving and break relays fill, and BB respectively. VVindings W, and

W, are connected in series with a resistance It, and the armature T, of the transmitting relay, while windings VI, and W, are connected in series with resistance R and the armature T of a similar transmitting relay.

Marking and spacing signals maybe transmitted by armature T through the sounder S as well as through the relays RR, and B3 If: key K is closed and it the armature T of the transmitting relay remains closed against its marking contact, then the closure by armature T of its marking contact will cause a marking signal to be transmitted through the sounder S, and, at the same time,

armatures U and V will synchronously move to their marking contacts. Armatures U and V will remain biased against their marking contacts. \Vhen the armature T closes its spacing contacts, a spacing signal will be noted at the sounder S,and armatures U /and V, of relays RR, and BB respectively, will move synchronously to their spacing contacts S, armatures U and V, of relays RR, and BB respectively, still remaining biased against their marking contacts,and so on. Similar effects are produced when the armature T is moved back and forth between its marking and spacing con tacts while key K remains closed and armature T, remains biased against its marking contacts.

Key K may be operated to transmit marking and spacing signals to both receiving relays as well as both break relays, assuming, of course, that armatures T and T are held against their marking contacts. \Vhen key K.

is opened, battery B which may be of a po tential substantially twice that of battery B or battery B these batteries being of substantiallythe same potential, and is poled oppositely with respect to these batteries, will be in series with windings W and W as well as with windings W and W so that substantially no current may flow therethrough. Yet, the current which normally flows through windings W and W. due to the series connection of battery B and the current which normally flows through windings WV, and due to the series connection of battery B are both so directed by these windings as to produce spacing elfects on their correspending armatures so that these armatures, namely, U and V and U and V will be moved synchronously to their spacing contacts. When key K becomes closed, battery B is disconnected from the circuit so that comparatively large marking currents flow through windings W and W. as well as through windings W and WV and these marking currents produce marking effects upon their armat-ures which overcome the spacing effects produced by the flow of currents through windings W and W and and V Accordingly, armatures U and V, and U and V will move to their marking contacts, and so it continues.

Fig. 3 shows a curve characteristic of the current that flows through the winding of a telegraph sounder when the associated transmitting key is operated, in systems not employing the principles of this invention. If it be assumed that the telegraph key is opened and closed at time intervals which are sub stantially equal, each time interval being,

- creased, while the length of the spacing signals will therefore be correspondingly increased. I

Fig. 4 shows the characteristic curve of current through the winding of a sounder connected in a telegraph system based upon the principles of this invention. Here, when the key is closed, the current increases to its steady value exponentially, as heretofore, and, when the key is open, the current decreases to its negligible value exponentially, also. It will be clear that if the magnetization required to operate the sounder were one-half of the total magnetization during the steady state, then the length of the marking and spacing signals will be substantially equal to each other, and the distortion present in former systems will be practically eliminated.

While this invention has been shown and described in certain particular embodiments merely for the purpose of illustration, it will be obvious that the general principles of this invention may be applied to other and widely varied organizations without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

1. In the subscribers loop of a telegraph system, the combination of a sounder, a source of potential in series with the winding of said sounder, a key, and a second source of potential, the said second source of potential being shunted by the said key when said key is closed, said second source of potential being connected in series with the winding of said sounder upon the opening of the key.

2. In a telegraph system, the combination of a sounder, a source of potential in series with the winding of said sounder, a key also in series with the winding of said sounder when said key is closed, and a second source of potential, said second source of potential being shunted by said key and being ineil'ective when said key is closed, said second source of potential being effectively connect ed in series with the winding of said sounder when said key is opened, said key being employed to cause the production of marking and spacing signals by the sounder.

3. In a telegraph system, the combination of a sounder, a battery in series with the winding of the sounder, a key similarly in series with the winding of the sounder when said key is closed, and a second batter said second battery being connected to the series circuit by the'opening of said hey, the operation of the key at a normal rate causing the operation of the sounder to produce marking and spacing signals without distortion.

&. A telegraph system comprising a line, a key, a sounder, a break relay having two windings and an armature, a transmitting relay having an armature which may operate to connect marking or spacing battery thereto, the line being serially connected to the key, the winding of the sounder, one winding of the break relay and the armature of the transmitting relay when the key is closed, the other winding of the'break relay being connected between the armature of the transn'iitting relay and ground through resistance of a definite magnitude, and a source 0i counter electromotive force which may be effectively connected to, or disconnected from, the series circuit by the respective opening or closing of said key.

5. In a telegraph system, the combination of a sounder, a relay having an armature which may vibrate to cause the sounder to produce marking and spacing signals, a telegraph key which is closed when the armature of said relay vibrates, said telegraph key being operated to produce marking and spacing signals at the sounder if the armature of said relay remains stationary, and a source of direct current potential which may be connccted to, or disconnected from, said sounder by the operation of said telegraph key.

In testimony whereof I have signed my name to this specification this 18th day of August, 1927.

nor B. snanon.

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