US2238136A - Auxiliary telegraph signal transmitter - Google Patents

Description

prfl W, 1941. J. A. SPENCER AUXILIARY TELEGRAPH SIGNAL TRANSMITTER Filed May 28, 1938 INVENTOR. JAMES Z ATTORNEY.

Q W &

m 2 WEQ i 6 w Q1:353:532E3;222: 2 21 2 1 t V NE: SN

Patented Apr. 15, 1941 AUXILIARY TELEGRAPH SIGNAL TRANSMITTER James A. Spencer, Teaneck, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application May 28, 1938, Serial No. 210,669

12 Claims.

This invention relates generally to printing telegraph systems and particularly to devices for transmitting auxiliary signals independently of the traific signals which normally are transmitted under control of a perforated tape. The invention as herein shown and described is particularly applicable to the requirements of simplex and synchronous multiplex telegraph systems. The preferred embodiment of my invention is also adapted for use in connection with the so-called Z-unit equal length printer code. This code is advantageously used on radio telegraph channels for the reason that it provides a basis for the automatic detection of errors due to the mutilation of signals.

Details of a system for automatic error detection of mutilated signals are shown and described in U. S. Patent 2,183,147, granted December 12, 1939, to John B. Moore and Richard E. Mathes. According to the teachings of Moore and Mathes each of the code combinations of a 7-unit code or an S-unit code is characterized as having a fixed ratio between the number of marking units and the number of spacing units.

It is one of the objects of my invention to provide an idle-time signalling device which may be automatically put into service during periods of any considerable duration between successive message transmissions whereby the radio channel between stations may be monitored and held in readiness for further message transmissions, without the necessity for reestablishing. synchronism between the sending and receiving apparatus.

It is a further object of my invention to provide facilities for the transmission of auxiliary signals independently of the ordinary tape-controlled operation of the channel as in synchronous multiplex work.

These auxiliary signals are sometimes termed service signals and are useful for indicating starting and stopping periods in the transmission of trafiic signals as well as in order to indicate departures from normal conditions of transmission and reception. e

Other objects and advantages of my invention will be brought out in the detailed description to follow.

My invention will be better understood by reference to the accompanying drawing which comprehends one figure only. This figure shows a schematic circuit diagram comprising means for transmitting auxiliary service signals as well as means for the transmitting of an idle-time signal.

j the outgoing line.

rings #2 and #4.

Referring to the drawing, I show therein an arrangement of signalling elements I to I, inclusive, which are included within the broken line rectangle T, these elements being arranged as contact tongues 8 which are positionable in contact either with positively or with negatively polarized feeder contacts 9 and i0, respectively. The tongues 8 are arranged to be set in their alternative contacting positions in response to the operation of a set of seeker pins which are controlled by perforations in the transmitting tape. According to a recently adopted practice in the transmission of printing telegraph signals, the message to be transmitted is first perforated in 7-unit code signals on a strip of paper tape which is fed at a cyclic rate to the transmitter. Different code combinations are thus set up on the tape-controlled tongues 8 for transmission of marking or spacing signalling elements in each of the seven positions of a uniform length code signal. The particular code combination required for transmission of a given character is thus communicated to the transmitting segments of a multiplex distributor.

Such a distributor is shown generally at D and has preferably four rings. Ring #9 comprises individual code element segments for a plurality of channels of the multiplex system. Ring #3 is merely a collector ring connected to The brush ll bridges the segments of ring #I successively across to ring #3. Ring #2 has segments corresponding to those of ring #I, while ring #4 is a collector ring cooperating therewith. Brush l2 bridges The brushes H and I 2 are insulated from one another but are mounted for synchronous rotation, being preferably driven by a synchronous motor which is held in step with other portions of the multiplex telegraph system, in accordance with any of the usual methods of synchronization. The purpose of the segments in ring #2 will be explained later.

Since there are two main functions to be performed by the auxiliary signalling device of my invention, I will first describe how an idle-time signal may be transmitted, and subsequently I will describe how any one of a plurality of service signals may be transmitted.

Certain of the code signalling tongues 8 are connected through contacts I3, l4 and I5 of a relay l6 and thence through other contacts of the service signalling device, which is camoperated, to the respective segments of the distributor ring #I to which they are appropriate. Only one of the tongues 8, namely, that which is in position 1, leads directly to its segment i in ring #1 of the distributor. Code signalling tongue 8 in position 2 is connected through a back contact and armature-operated spring l3, and thence through mutually contacting springs H and M3 to segment 2 in distributor ring #1. In code signalling position 3 the tongue 8 is connected to mutually contacting springs Hi and 20 and thence to segment 3 in ring #I of the distributor. The signalling tongues 8 in positions 4 and 5 are likewise connected to their respective segments in the distributor ring #I, but by way of mutually contacting springs 2| and 22 in the case of the tongue 8 in position 4, whereas the tongue 8 in position 6 is connected through mutually contacting springs 25 and 25 to distributor segment 6. The connections of the tongues 8 in positions 5 and I, respectively, are

similar to that of the tongue 8 in position 2.v In

other words, the conductive circuits from these tongues 8 to their respective segments comprise back contacts and operating contacts M and on relay l6, as well as mutually contacting springs 23 and 24 in the one case, and 2'! and 23 in the other case.

When traffic signals are being sent, the perforated tape is fed at a cyclic rate through the transmitter whereby the transmitter tongues 8 are controlled and the marking and spacing (or positive and negative) signals are thus communicated to the segments of the distributor ring #I. These signals are then sent out over the synchronous multiplex channel in accordance with the rotation of the brush II. The transmitter T is, therefore, normally uninfiuence d by either the relay [6 or by the contacts I! to 23, inclusive, which latter contacts are designed for transfer of operating control from the transmitter T to the auxiliary signalling device whenever it is required that a service signal shall be transmitted.

In positions 2, 5 and 1 the transmitting tongues 8 may at times be disconnected from their respective distributor segments, as when the relay i6 is operated. The purpose of the relay I5 is to make it possible to repeatedly transmit an idle-time signal. The composition of the signal itself is of importance in carrying out my invention. Thus, it will be noted that t consists of three marking elements in positions 2, 5 and I of the uniform length code signal. These marking elements are communicated to distributor segments 2, 5 and I on ring #l by virtue of the fact that upon energizing the relay 16 its operating contacts I3, l4 and I5 are respectively fed with positive (marking) current from the same source B which feeds the contacts of the transmitter T. This code combination consisting of marking elements in positions 2, 5 and I has been chosen to indicate that the channel is being maintained ready for service. but the signal itself is ineffective in selecting any of the type bars of a receiving printer such as would be operated in response to traflic signals at the receiving end of the multiplex channel. In the case of failure of the channel itself these idle-tirne signals would not be received. or else they might be received in a mutilated form. In either case the printer is adapted to make a peculiar response such as to designate the interruption of service on that particular channel. Immediately upon reception of such a failure indication steps can be taken at the receiving end to notify the transmitting operator or others so that the faults may be corrected,

or so that the transmission of traffic signals may be postponed until satisfactory service conditions are restored.

The idle-time signals may be transmitted at will by energizing the relay 56 under control of a manual switch indicated generally at MS. This switch comprises a manual lever 29 having thereon a device 38 which engages with a contact spring 3| and. presses the latter against a companion contact spring 32. The winding of the relay It may be fed with positive potential from the source B by Way of a resistor 33. The return circuit for the relay winding is through contacts 32 and 3| to the negative side of the source B. The manual switch MS is mechanically linked to the operating mechanism of the transmitter T in such a manner that the contacts 3i and 32 will be closed only upon completion of the transmission of a given character signal. The details of this association of the manual switch MS and the operating parts of the transmitter are not herein shown since they have been used in the prior art.

I have, however, shown an operating magnet 34 by which the seeker pins H and the tape feed mechanism, including the sprocket Wheel 35, are synchronously operated. The timing of operation of the magnet 36 is obtained by feeding positive current to ring #4 and across brush I2 preferably to segments 8, 9 and iii (of ring #2) which are connected in common to conductor 36 leading to contacts 31 and 33 of a differential relay Ml. Contact 38 feeds to one of the windings of relay 41) and thence to the windings of relay 34 over the common conductor 6!. The other terminal of the windings of operating magnet 34 is connected to the negative side of the source B.

The relay 4B is designed to operate when one only of its windings is energized, but will not cperate when both windings are energized, since the direction of current therein as arranged to neutralize the magnetization of the relay core. Normally, then, the local impulses which are transmitted over segments 8, 9 and H) to conduotor 36 will be branched so that both windings of relay 40 will be simultaneously and equally energized. The branch for the left-hand Winding of relay 46 may be traced through conductor 42 to contact 43 and a companion contact 4% and thence over conductor (*5 to mutually engaging contacts 46 and M and to the left relay winding 40. The circuit just now traced may he opened upon the occurrence of either of two conditions. Under one of these conditions the tape-slack between the perforator (not shown) and the sprocket Wheel 35 of the transmitter may be reduced to the point where contacts 46 and i! are opened. Only the right-hand winding of the relay 40 will remain energized and hence this relay will pull up its armature :8 for engagement with contact spring 38. The spring combination 31, 38 and 48 is of the make-before-break type. Consequently, the operating magnet 36 instead of being fed with positive impulses from ring #2 in the distributor will now be fed with a steady current from the source B over conductor 49, contacts 48 and 38, the right-hand winding of relay M1, and thence to the windings of operating magnet 34 to the negative side of the source B. The operating magnet 34 will now be locked up and the transmitter will wait until sufiicient slack in the tape is restored so that contact may be made between springs 46 and 4'! for neutralizing the magnetization of the windings in relay 40. Upon release of the armature 48 normal transmitting conditions will be restored. The interruptions of transmission incident upon failure to feed the transmitting tape as rapidly as the transmitter can use it are, generally speaking, of short duration and do not require the transmission of idle-time signals for maintenance of service on the communications channel. Longer interruptions, however, which call for shutting down the transmitter, entail the setting of the manual switch MS so that cont-acts 3| and 32 will be closed and relay l6 operated. There is another function performed by the manipulation of the lever 29 besides closing the contacts 3i and 32. It is to arrest the tape feed mechanism without mutilating the code elements set up b y the tongues 8. The mechanism for performing this function is not shown or described herein because it is old in the art and is separate and distinct from the objects of my invention.

I will now describe a mechanism which is useful for the transmission of special service signals.

To a certain extent this mechanism follows the teachings of the prior art, particularly as illustrated by United States Patent #1,2'75,559 granted August 13, 1918, to W. A. I-Ioughtaling. However, there are certain novel elements of construction residing in the mechanism as herein shown and described and these will be brought out more particularly in the claims to follow.

The special service signals to be transmitted by means of a supplemental signalling device are those whereby any one or more taps of a bell may be produced at the receiving end. Although the perforator keyboard is usually provided with a certain key for perforating a code signal the significance of which in the shift position is functional and results in the ringing of a bell attached to the receiving printer, it is often required that the bell signal shall be transmitted independently of any prepared code signals as perforated in the tape. Accordingly, I provide a dialing member 50 for special transmission of a series of code signals. The extent of movement of the dialing member 50 is determined by placing ones finger in any one of the holes and drawing the member toward oneself until the finger strikes a stationary stop The operator then withdraws his finger from the selected hole El and releases the dialing member to be restored to its normal position under the influence of a coiled spring 6!], this spring having been wound by the previous motion of manual dialing. A gear is loosely mounted on the shaft till and has projecting therefrom a pivot pin for supporting a pawl 6| which is adapted to engage with the teeth of a ratchet wheel 58 fixedly mounted on the shaft 51. The dialing member 56 and a switch-controlling dog 59 are also fixedly mounted on the shaft 51. During a dialing operation the pawl 6i ratchets over the teeth of the ratchet wheel 58, but during the return motion of the shaft 51, the pawl 6| is engaged by a tooth of the ratchet wheel 58 and caused to rotate backward, with shaft 51 carrying its gear 56 and so imparting rotation to the pinion 54 fixedly mounted on the shaft 53. This shaft 53 also carries a series of code impulsing cams C1 to C5, inclusive, and a ratchet wheel 55, all fixedly mounted thereon.

The cam shaft 53 can rotate only as permitted by the operation of an escapement whose arms 63a are integral with an armature 63 which is positive under control of a pulsating magnet 62. The impulses for actuating the magnet 62 are derived from the source B fed through distributor ring #4, and across brush I2 to segments 8, 9 and ID of ring #2. This circuit may be further traced through conductors 36 and 42 to contact springs 43, and 69 and thence to the windings of magnet 62 and finally returning to the negative side of the source B.

The circuit just described is one which is formed upon manipulating the dial member 50, due to the fact that the dog 59 has been thereby withdrawn from pressure against the resilient contact spring 43. The tension in this spring urges it, when released, away from contact with spring 44 and in contact with spring 69 which is in circuit with the winding of magnet 62. The operating impulses from the distributor ring #2 are, therefore, transferred from the operating magnet 34 of the transmitter to the escapement magnet 62 of the auxiliary signalling device.

Depending upon the hole 5| which is fingered, from one to five strokes of the bell will be produced at the receiver. However, it requires the shift signal, the bell signal, and the unshift signal for each stroke of the bell. Consequently, the code determining cams C1 to C5, inclusive, are provided for setting up these code signals and for transmitting the same.

Upon each revolution of the brush 12 a single impulse will be transmitted tothe escapement magnet 62.. Consequently, successive signals as set up on the peripheries of the cams C1C5 will be transmitted over the transmitting segments 2 to 1, inclusive, on ring #I of the distributor C.

The cams C1 to C5, inclusive, are shown( in their normal or inactive positions whereat each of the even-numbered contact springs I 8 to 23, in.- clusive, rests against its associated lower contact spring, there being a notch in each one of the cams for permitting this connection to be made.

By rotating the cams through an arc of 18 which is the angle subtended by one of the teeth of the ratchet wheel 55, it will be seen that raised portions of cams C1, C2 and C3 come under their associated control springs I 8, 2|] and 22, respectively. At this step of the operation positive (marking) current is fed from the source B through the upper contacts with which the operating contacts I8, 20 and 24 are now in the make position and hence enabled to transmit current to segments 2, 3 and 4, respectively, on distributor ring #I. This transmits the signal which has been arbitrarily chosen as the figure shift signal.

Art the next step of the escapement wheel 55 cams C2 and C5 are in position for elevating their operating springs 20, 26 and 28, thereby to impress positive current upon distributor segments 3, 6 and 7. This is the composition of an arbitrarily chosen signal for the bell ringing function on the printer. The bell signal (following the shift signal) usually corresponds with the signal for the letter J; but, if preferred, it may be the same signal as chosen for the letter S, or any other lower-case character on the keyboard.

In the next position of the escapement wheel 55, cams C2, C3 and C4 are in position to elevate their operating springs 20, 22 and 24, respectively, thereby to impress positive current upon distributor segments 3, 4 and 5. This is a signal arbitrarily chosen to designate the unshift function.

The steps of operation of the cams as thus far described are those which would be performed if the operator wished to transmit a single-stroke bell signal. He does this by inserting his finger in the hole of the dialing member nearest the stop 52. The four steps necessary to transmit such a signal are, respectively, shift, bell, unshift and finally the normally inactive position. When the number of strokes of the bell is to be greater than one, the extent of motion of the dialing member 58 is determined by the hole 5! which is fingered by the operator, and accordingly, any selected are of a revolution of the cams may be traversed for transmitting a proper sequence of signals necessary to produce the desired number of taps of the bell. Usually from one to five strokes are sufficient for all of the usual service signals such as start, re-run, re-punch, stop and regulate.

It should be noted particularly that the circuit diagram as shown is such that certain series connections are formed through the trafiic code determining elements 8 of the transmitter T, through back contacts and operating contacts of relay It, and thence through cam operated contacts of the auxiliary signalling device to the distributor segments. However, in code element position I a direct connection is made between the first code element tongue 8 and segment I on distributor ring #I. l

Furthermore, in code element positions 3, 4 and 6 there is no the relay [5, but these connections are directly from the tongues 8 through cam operating contacts to distributor segments 3, 4 and 6, respectively.

It is, of course, to be understood that this arrangement is arbitrary and that if the character designations of the different code signals were to be altered, corresponding changes would be made in the circuit diagram.

Reviewing the operation of my improved auxiliary telegraph signal transmitter, it should be noted that the brushes I! and I2 are caused to rotate over their respective distributor rings of each station. The diagram shows two rings #l and #3 assigned to the signalling circuit. The additional rings #2 and #4 are required to perform the local functions as heretofore described. One of these local functions is to operate the transmitter and the automatic control. The operating impulses are supplied to the magnet 34 and at times to the auxiliary signalling device escapement magnet 62. The transfer of these impulses is made by the off-normal switch whose dog 59 releases the spring 43 whenever a dialing operation is made for transmitting a desired r number of repetitions of the bell signal. At the time of this transfer of operating impulses the tension of the spring 43 is such as to urge it against contact spring 69 after opening the circuit between contact springs 43 and 44.

It is clear from the above given description that in dialing to produce any number of strokes of the bell the cam shaft 53 will be rotated through an are which is a corresponding multiple of 72. The outgoing signals are impressed upon a synchronous multiplex channel under control of the escapement whose armature 63 responds to the impulses applied to the operating magnet 62 by the multiplex distributor brush l2. The rotation of the cams C1 to C5, inclusive, is, therefore, synchronized with the passage of the brush l2 over segments 8, 9 and is. Four steps are. required for each stroke of the bell signals- Since there are twenty teeth in the ratchet wheel 55 each transmission of the bell signal represents need for including contacts of 1 of a revolution of the cams C1 to C5, inclusive. The peripheral characteristics of the cams C1 to C5 are, therefore, repeated every 72 of their circumference. This allows of repeating the bell signal five times with one revolution of the cam shaft 53.

During the transmission of the shift, the bell, and the unshift signals, it will, of course, be appreciated that the operation of the transmitter T is temporarily interrupted. This interruption is attained by opening contacts 43 and 44 which are included in the circuit to the left-hand winding of relay 40. This causes the right-hand winding to act alone in locking up the relay so as to deliver a steady current from the source B through th armature 48 and its front contact 38, thence through the operating winding of relay 4El and the windings of magnet 34 and returning to the negative side of the source B.

When the dialing member 50 is released, the cam shaft revolves under tension of the spiral spring Bil, as previously mentioned, but only at the impulsing cadence which is obtained by the passage of brush l2 over the distributor segments 8, 9 and H) on ring #2, since the impulses so produced serve to actuate the escapement magnet 62.

It may well be that certain of the segments in distributor ring #2 have no connections thereto; nevertheless those segments which are tied together are useful for maintaining a properly timed relation between the transmitter-operating impulses appropriate to the different channels of the multiplex system. Other devices (not shown) may also be maintained in synchronism in accordance with the sweep of the brush [2 over different segments of ring #2.

Thus, assuming that the transmitter T is assigned to channel A whose distributor segments in ring #I are numbered I to 1, inclusive. Then segments 8 to M may be considered as appropriate to channel B, while segments 15 to 2| are appropriate to channel C. The assignment of segments in ring #2 for correctly timing the action of different transmitter operating magnets (such as magnet 34) will be as follows:

Transmitter T for channel A uses segments 8, 9 and I9. Channel B uses segments !5, l6 and I1, while channel C uses segments l, 2 and 3. By this arrangement the seeker pins are withdrawn from the tape a moment following the pick-up of the signals as determined by the setting of the code element numbers I to l, inclusive (for channel A). With regard to the other channels the corresponding operating magnets 34 are energized, for channel B, immediately after the pick-up of the code signals on segments 8 to M, inclusive, of ring #I, and, for channel C, immediately after the pick-up of code signals on segments l5 to 2|, inclusive.

It will be noted further that the operation of the idle-time signalling device is entirely independent of otoher mechanisms except that it is under control of the manual switch MS, and when in service the operating magnet 34 for the transmitter on a given channel is locked up while the tape feeding mechanism is held inactive. It may be seen that within the complete multiplex system any one or more of the multiplex channels may be shut down independently of the others. The idle-time signal will then automatically take the place of the traffic signals on such channels as are shut down. Transmission of the idle-time signals has a certain value other than for differentiating between fades and spaces because when signals are transmitted on each of plex printing telegraph system which connects transmitting and receiving stations over a radio channel.

Various modifications of the invention will doubtless suggest themselves in view of the foregoing description; The scope of the invention is, therefore, to be considered as having as great breadth as is permitted by the claims.

I claim:

1. A telegraph transmitting system comprising a line, a code impulse distributor having at least seven code-element circuit terminals and means for sequentially connecting the same to said line, transmitting means for impressing upon said terminals trafiic code signals of the type wherein a fixed ratio is maintained between the number of marking elements and the number of spacing elements of each code signal, a perforated tape and tape feeding device for controlling said transmitting means, impulsing means associated with said distributor for producing a step-by-step operation of said tape feeding device, manipulative means for starting and stopping said tape feeding device, and means under control of said manipulative means for causing an idle-time signal to be transmitted during relatively long inactive periods of said tape feeding device, said idle-time signal being characterized by a number of marking and spacing impulses the ratio between which is the same as the afore-mentioned fixed ratio. r

2. A system in accordance with claim 1 and having means including a switch operable under control of a predetermined tension on said tape for arresting said tape feeding device.

3. In a telegraph transmitting system, a line,

i a distributor, a perforated tape transmitter operable to impress ,7-unit code signals throughsaid distributor to said line, each of said signals being composed of marking and spacing units the nu-- merical ratio between which is uniformly fixed, means in circuit between said transmitter and said distributor for at times impressing an idletime signal on said line, said idle-time signal being characterized by conformity of its marking and spacing units to said fixed ratio, and manipulative means operable to shut down said transmitter and to render the idle-time signalling means operable thereafter. I

4. A system in accordance with claim 3 and including means in circuit between said transmitter and said distributor for transmitting auxiliary service signals, said means comprising a plurality of cam-controlled switches and means for characterizing said service signals by conformity of their marking and spacing units to said fixed ratio, said system also including means operable bysaid service signal transmitting means for interrupting the transmission of signals by either of the other two said signaling means during transmission of a service signal.

5. Station equipment for transmitting multiplex printing telegraph code signals comprising a tape-controlled code signal transmitter, impulse-driven means connected to certain operating segments on a multiplex distributor for actu- 5 ating said transmitter and for feeding the tape at a predetermined rate, a plurality of at least seven code-composing members settable in accordance with a uniform number of perforations in the tape for each code signal to be transmitted, said members being adapted to be released periodically by said impulse-driven means, an idletime signalling device comprising a relay having at least three movable contactors each associated with a front and a back contact, each front contact being connected to a source of current, and each back contact being connected to an appropriate one of said code-composing members, circuits connecting said movable contactors with appropriate segments on said multiplex distributor, and manually operable means for interrupting the tape-feeding function of said impulse driven means while causing the relay of said idletime signalling device to assume and to maintain an operated condition.

6. Station equipment for transmitting multiplex printing telegraph code signals comprising a tape-controlled code signal transmitter, impulse-driven means connected to certain operating segments on a multiplex distributor for actuating said transmitter and for feeding the tape at a predetermined rate, a plurality of at least seven code-composing members settable in accordance with a uniform number of perforations in the tape for each code signal to be transmitted, said members being adapted to be released periodically by said impulse-driven means, an auxiliarysignalling device comprising a pluralityof sets of code-element determining switches and cams for throwing said switches, each of said switches being of the double-throw type, manipulative means for initiating a desired movement of said cams, magnetically controlled escapement means for causing said cams to throw said switches permutationally and sequentially and hence to cause a desired succession of service signals to be transmitted in place of signals initiated by said tape-controlled code-composing members, said switches being severally arranged while in a normal position to interconnect certain of said code composing members with appropriate segments on said multiplex distributor, said cams constituting means for characterizing each of said service signals as having a fixed ratio between the number of marking elements and the number of spacing elements thereof, and means including an off-normal switch operable by said manipulative means for shifting the connections of said operating segments on the distributor from said impulse driven means to said escapement means.

7. In a telegraph transmitting system, means including a perforated tape for storing 7-unit code signals, a tape-controlled transmitter including a distributor, means including a magnet for feeding said tape through said transmitter at a cyclic rate which is synchronized with the operation of said distributor, a tape supply source operable at an irregular speed, manipulative means having an escapement magnet associated therewith for initiating service-signals, a differential relay having two windings opposingly connected in parallel circuits, both said windings being series-connected to said tape-feeding magnet, said relay having a make-before-break contact assembly which is adapted to close a pulsating circuit from said distributor through one of the relay windings when said relay is de-magnetized, said contact assembly being further adapted to feed a constant current through the last mentioned winding when said relay is mag netized, two circuit breakers both in series with the other winding of said relay, one of said circuit breakers being operable by the tape when subjected to a given take-up of its slack, the other of said circuit breakers being operable by said manipulative means, said tape feeding magnet being subject to a locking-up control by said relay upon opening either one of said circuit breakers, and means operable by said manipulative means for completing said pulsating circuit through said escapement magnet whenever a service signal is to be transmitted.

8. In a telegraph transmitting system a distributor having separate segments for the respective code elements of uniform length code signals, a tranic signal keying device, a servicesignal keying device, both said devices having circuit connections to said segments and means for causing selected 'l-unit code signals to be sent out through said distributor, an idle time keying device having means operable to compose a characteristic I-unit code signal, additional circuit connections between certain of said segments and said idle time keying device, and means including a rela automatically effective during relatively long periods between transmissions of traffic signals by said traffic signal keying device for repeatedly sending out an idle-time signal 'hrough said additional circuit connections and the segments connected thereto.

9. In a telegraph system adapted to transmit 'l-unit code signals and comprising a transmitter having a tape feeding device and an operating impulse circuit therefor fed with energizing current through a distributor, and comprising further an auxiliary service signalling device, the method of sending out tra fiic signals, auxiliary service signals, and idle-time signals alternatively, which comprises completing said operating impulse circuit through said tape feeding device as long as there is sufiicient slack in the tape to be utilized by the transmitter, or until the transmitter is manually shut down, automatically interrupting said circuit and locking up the transmitter whenever a shortage occurs in the supply of said tape, manually causing said circuit to be interrupted and the transmitter to be locked up whenever a service signal is to be sent out, completing said operating impulse circuit in that event through said service signalling device, manually selecting a desired number of transmissions of said service signal to be made sequentially, manually effecting an automatic control whereby said idle-time signal is substituted for said traffic signals during any substantial period of shut-down of said transmitter, and causing said idle-time signal to be sent out repeatedly and in synchronism with the cyclic operation of said distributor.

1i). Signal transmitting apparatus adapted for use in a synchronous printing telegraph system comprising a line, a perforated tape controlled transmitter, an auxiliary signalling means, cyclically operable means for controlling the operation of said transmitter and of said auxiliary signalling means alternatively, manipulative means for transferring the effects of said cyclically operable means from control of said transmitter to control of said auxiliary signalling means for a predetermined time interval, an idletime signalling device adapted to be interposed in circuit between said transmitter and said line, and manipulative means for transferring the effects of said cyclically operable means from control of said transmitter to control of said idletime signalling device for a period of indefinite duration.

11. In a telegraph transmitting system, a line, a distributor, three alternatively usable code signal composing devices each operable to impress code signals through said distributor to said line, each of said signals being distinguishable from a stray signal by virtue of a fixed numerical ratio which is maintained between its marking and spacing units, the first of said devices having a set of perforated tape-controlled polarity reversing switches having at least seven tongues corresponding respectively with the several units of a code signal, the second of said devices having an idle time relay the back contacts of which are connected to certain of the tongues of said polarity reversing switches and the front contacts of which are fed with marking signal potential, means for jointly operating the tongues of said relay from back-to-front contact circuit closure positions, the third of said devices comprising a set of cams and switch tongues controlled thereby, each said tongue being movable by its cam between a back and a front contact, each of the last said back contacts being connected to a respective one of the tongues in one and the other of the two code signal composing devices first mentioned, and each of the last said front contacts being fed with marking signal potential, means operable under control of the tape fed to the first said code signal composing device for actuating said relay, and manually operable means for disabling the first and second said code signal composing devices and for operating said cams to compose a predetermined succession of service signals.

12. In a telegraph transmitting system, a line, a distributor, three alternatively usable code signal composing devices each operable to impress code signals through said distributor to said line, each of said signals being distinguishable from a stray signal by virtue of a fixed ratio which is maintained between its marking and spacing units, the first of said devices having a set of perforated tape-controlled polarity reversing switches each under control of a different line of perforations in the tape and each normally connected to an appropriate segment on said distributor, an idle time signaling device constituting the second of said signal composing devices and comprising circuit connections to said distributor, a manually operable service signaling device constituting the third of said signal composing devices and comprising circuit connections to said distributor, means operable upon connecting any one of said signal composing devices to said distributor for disconnecting the others therefrom, and means for transferring the source of signals as impressed upon said line-from one to another of said signal composing devices while maintaining said distributor continuously rotative for synchronizing of a receiving distributor therewith.

JAMES A. SPENCER.

Images