US2370445A - Supervisory signal system - Google Patents

Description

Feb. 27, 1945. A. l.. BROWN SUPERVISORY SIGNAL SYSTEM Filed oct. 31, 1942 2 sheets-sheet 1 Y V vA'I'I'ORNEY 'Jew Rishi.

l SMQ UR ms mlb-M- Patented Feb. 27, 1945 2,310,445 sUrERvrsonr SIGNAL SYSTEM Andrew L. Brown, Brooklyn, N. Y., assigner to Radio Corporation of America, a corporation of Delaware Application October 31, 1942, Serial No. 464,019

. 6 Claims.. (C1. 178-3) This invention relates to supervisory signal systems and more particularly to a service signaling arrangement for use in connection with commercial telegraph systems.

Devices for transmitting auxiliary signals independently of the traiiic signals are well known in the art. It is conventional to use a perforated tape transmitter for trailic signals and to use an auxiliary keying device for actuating a bell signal, for example. An auxiliary keying device of that type is disclosed in United States Patent No. 2,238,136, granted April 15, 1941, to James A. Spencer.

According to the disclosure of the Spencer patent, it was possible to transmit automatically a succession of signals which comprised case shift and bell ringing signals for producing any number of bell strokes, say from one to ve. In this manner, the different service signals could be transmitted at any time when it was necessary to interrupt the operation of the tape transmitter.

It has been the usual practice heretofore to transmit the same signal for bell ringing as for the letter "S or J. In order to differentiate between the two functions of the same signal, it was necessary whenever the bell signal was to be transmitted to precede the same by a gure shift signal and to follow the bell signal by a letter shift signal.

The transmission of a signal for each bell stroke thus required, according to the prior art, the transmission of three code signals. These three code signals had to be repeated for each stroke of the bell. It is, accordingly, one of the principal objects of my invention to provide an improved service signal device wherein the bell signal may be transmitted and received without resorting to the use of case shift signals.

It is another object of my invention to provide a circuit arrangement which incorporates facilities for transmitting service signals, in addition to an idle-time keyer and a tape stop device operable in response to the take-up of slack in the tape by the tape transmitter.

It is still another object of my invention to provide receiving means selectively responsive to a service signal and independent of other facilities for control by ordinary traflic signals.

A feature of my invention resides in its adaptation for the efficient transmission of bell signais. and its adaptation for conditioning the transmitter to send an idle-time signal whenever the tape transmitter is stopped longer than to detect the mutilation of a bell signal at the receiving station.

One of the dimculties which have been encountered in the past is that the use of case shift signals in combination with the bell signals occasionally resulted in the failure of the receiving printer to properly transcribe code characters following the transmission of the bell signal. This difficulty was encountered because the auxiliary service signaling device might "break in on the tape transmitter in the midst of transmission of upper case characters. The restoration of the printer unit to lower case characters was automatically performed as the last function in the automatic bell transmitting unit. Consequently, when the tape transmitter resumed its transmission, the receiving printer would be left in the lower case position and would thereby print incorrectly the characters which were intended to be in the upper case and until the tape transmission called for a letter shift signal.

Accordingly, it is an object of my invention to remedy the deficiency set forth in the preceding paragraph by utilizing a certain combination of code elements solely for the supervisory bell signal. By eliminating the need for the case shift signals preceding and following the bell signal, the auxiliary signal transmitter may be considerably simplified in design.

My invention will now be described in more detail, reference being made to the accompanying drawings, in which:

Fig. 1 shows a schematic circuit diagram in'- cluding an auxiliaryr service signal transmitter, an idle-time keying relay, -a tape-slack control device, and other apparatus units which are conventionally used at a transmitting station; and

Fig. 2 shows a circuit diagram appropriate for use in connection with apparatus units to be operated at a receiving station.

The transmitting apparatus Referring first to Fig. 1, I show therein an arrangement of signaling code composing switches comprised in a unit I0 and having seven selective circuits l to 1 inclusive which correspond with the seven code elements of a now wellknown seven-unit signaling code. The transmitter keying elements are arranged as contact tongues 8 which are positionable in contact with positive contacts 9 or with negative contacts Il, depending upon whether or not a perforation in momentarily. The invention is further adapted the tape l2 is sensed by an appropriate seekerpin 1I. For the sake of simplicity in the drawings, the mechanical association of the tongues 8 with the seeker-pins 1I. is merely indicated by an interconnecting dot-,and-dash line.

During the transmission of a message, the perforated tape I2 is fed at a cyclic rate and the perforations therein are sensed cyclically. Different code combinations are thus set up on the tape-controlled tongues 8 for transmission of marking or spacing signaling elements in each of the seven positions of a uniform length code signal. The code signals thus formed are normally applied to different segments on a multiplex distributor. Such a distributor is indicated as having a code element ring RI and a collector ring R3, the latter being connected to the outgoing line.

Merely by way of illustration, the transmitting distributor having rings RI and R3 is shown in Fig. 1 as arranged for a two-channel multiplex system. If the system were intended for three or more channels, then the number of segments in the distributor ring RI would be proportionately increased, and would be preferably a multiple of seven segments.

In addition to the signal transmitting rings of the distributor, it is conventional to provide a segmented local ring R2 and an energy feeder ring R4 associated therewith. whereby the cyclic operation of various mechanisms at the transmitting station may be properly timed. The use of the distributor rings R2 and R4 will be hereinafter described inmore detail.

The brush I8 is used to bridge rings RI and R3 while brush 20 is likewise used to bridge rings R2 and R4. These brushes are insulated one from the other, 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.

There are two main functionsto be performed by the auxiliary signaling devices herein shown. One of these is to transmit idle-time signals, and the other relates to the transmission of service signals such as are usually responded to at the receiving station by a predetermined number of bell strokes, for example.

The idle-time keying device comprises a relay I6 having three groups of double-throw switches, the tongues of which are referenced A2, A5, and A1. They relate to the transfer of three code element circuits from the tape transmitter Ill to a set of front contacts which are always supplied with positive potential.

'Ihe automatic bell signal keying device comprises a cam-operated switch having a follower arm 24 and idler roller 25 which rides over the periphery of a cam CI. The follower arm 24 actuates certain switch tongues BI, B4, and B1 which have front and back contacts associated therewith. The tongue A2 of relay I8 is connected to the back contact associated with tongue B2 in the bell-signal keying switch. Likewise, the tongue A1 in relay I8 is connected to back contact associated with tongue B1 inthe bell-signal keying switch. The tonguesB2, B4, and B1 are -connected respectively with segments 2, 4, and

1 in the distributor ring RI. The tongue 4 in the tape transmitter IIl is connected to the back contact associated with tongue B4 of the bell-signal keying switch.

The tongues 8 in positions I, 3, and 8 are unrelated to the keying operations for idle-time and bell-signal keying and, therefore, these tongues are connected directly to appropriate segments I, 3, andi in the distributor ring RI.

Whenever the transmission of trailic signals is to be interrupted for any appreciable time, it is desirable to maintain a succession of idletime signals on a radio channel in order to hold the apparatus units at the receiving end in synchronism with the transmitting distributor. It is usual, therefore, to close a key switch consisting of contacts 3l and 32 and having a toggle lever 29 which is manually operated. The closing of contacts 3l and 32 causes a negative potential to be fed from contact 32 through the coil of relay I6 and thence through a resistor 33 to the positive terminal of an operating source, not shown.

When relay I6 operates, its tongues A2, A5, and A1 are closed against front contacts which are supplied with positive potential and this causes positive marking signals to be applied to segments 2, 5, and 1 in the distributor ring RI. Bearing in mind that these segments are cyclically swept by the brush I8,-it will be seen that the idle-time signal goes out over the transmission channel each time the ring RI is traversed. and until the toggle switch lever 29 is restored to normal. Incidentally, the switch lever '8 may be used to lock up the tape transmitter in a manner described by James A. Spencer in his Patent No. 2,160,463, granted May 30, 1939.

When the transmission of traffic signals is resumed, the perforated tape is fed at a cyclic rate through the transmitter in accordance with the step-by-step feeding thereof as indicated by the use of ratchet wheel and associated driving mechanism under control of the operating magnet 34. This magnet is energized by the closing of a circuit through the two coils of a differential relay 40 which, when both are energlzed, provides no attraction upon the relay armature 48. However, the energizing impulse for magnet 34 is derived from positive potentials through ring R4 and certain segments in ring R2 when they are bridged by the brush 20. This operation takes place at the completion of sensing operations at each step of the tape control device.

The relay 40 is designed to operate when one only of its windings is energized, but will not operate when both windings are energized. Normally, then, the local pulses which are derived from segments 8, 9, and I0 in distributor ring R2 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 4I) may be traced from conductor 36 through conductor 42 to contact 43 and a companion contact 44 and thence over conductor 45 to mutually engaging contacts 46 and 41 to the left hand relay winding 40. 'I'he circuit just now traced may be 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 on the shaft of the ratchet wheel 35' of the transmitter may be reduced to the point where contacts 48 and 41 are opened. Only the right `hand winding of relay 40 will remain energized and hence this relay will pull up its armature 48 for engagement with contact spring 38. The spring combination 31, 38, and 48 is of the make-before-break type. Consequently, the operating magnet 34, instead of being fed with positive impulses from ring R2 in the distributor, will now be fed by contact may be made between springs 4l and 41 for neutralizing the magnetization in relay 4l. Upon release of the armature 46, normal transmitting conditions will be restored provided the idle-time control key 29 has not been actuated.

The auxiliary signaling device particularly for transmission of bell signals is herein shown'as a modification of certain apparatus which was particularly illustrated and described in Patent No. 1,275,559, granted August 13,- 1918, to W. A. Houghtaling. In the Houghtaling device it was necessary to transmit case shift signals before and'after the bell sounding signal. According to my invention, the necessity for transmitting case shift signals is eliminated.

The need for transmitting bell signals inde-l pendently of any signals which have been perforated in the tape' will be apparent to those skilled in the art. Such need arises commonly when there is any diillculty in reception and a part of the message must be repeated. However, there are a number of signals which can be made by means of dierent numbers of bell strokes. Accordingly, the extent of movement of the dialing member 50 may be determined by placing ones finger in any one of the holes 5| and drawing the member towards oneself until the finger strikes a stationary point 52. This operation is similar to dialing a number on a conventional telephone set.

When the operator withdraws his nger from the selected hole 5| and releases the dialing member 50 to be restored to its normal position under the influence of a coiled spring 60, this spring upon unwinding drives the shaft 51 which carries a ratchet wheel 58 fixedly mounted thereon. A gear 56 is mounted on the shaft 51 and has projecting therefrom a pivot pin for supporting a pawl 6|, this pawl being adapted to engage with teeth of the ratchet wheel 58. The dialing member 50 and a switch controlling dog 59 are also xedly mounted on the shaft 51. During a dialing operation, the pawl 6| ratchets over the teeth of the ratchet wheel 58, but during the return motion of the shaft 51, the pawl 6| engages with a tooth of the ratchet wheel and causes the latter to rotate backward, with shaft 51 carrying its gear 56 so asto impart rotation to the pinion 54 fixedly mounted on a shaft 53.

This shaft 53 also carries a code impulsing cam C| and a ratchet wheel 55, both ilxedly 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 under control of a pulsating magnet 62. The impulses for actuating the magnet 62 are derived from the source fed through distributor ring R4, and across brush to segments 8, 9. and v||| of ring R2. This circuit may be further traced through conductors 36 and 42 to contact springs 43 and 69 and thence to the winding of magnet 62 and finally returning to the negative side of the source. y

The circuit just described is one which is formed`upon manipulating the dial member 50,

due tothe fact that the dog 66 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 68 which is in circuit with the winding of magnet 62. The operating impulses from the distributor ring R2 are, therefore,"\transferred from the operating magnet 34 of the transmitter to the escapement magnet 62 of the auxiliary signaling device.

Depending upon the hole 5| which is fingered, from one to ve strokes of the bell will be produced at the receiver.

Upon each revolution ofthe brush 20, a single impulse will be transmitted to the escapement magnet 62. Consequently, successive signals composed of marking elements in positions 2, 4,

f and 1 of the seven-unit code will be transmitted over segments 2, 4, and 1 on ring RI.

When the idler roller 25 rides over a hump in the cam CI, it restores the switch tongues B2, B4, and B1 to their back contacts. Only when the roller 25 rides into a depression in cam C| will the marking impulses be applied to segments 2, 4, and 1 of the distributor ring for transmission of the bell signal. This signal has been selected as one which is not used for character selection in traflic signaling. A different combination may, however, be substituted, since in the seven-unit code, there are 35 possible code combinations, whereas in the five-unit code only 32 kcombinations are available.

The gear ratio is made such that the cam C| will move the follower arm 24 through a complete operating cycle corresponding to each position of the holes 5| in the operating segment 50. Furthermore, the bell signal is transmitted upon every other passage of the brush 20 `over segments 8, 9, and l0, so long as the lever arm 59 is off normal and permits contact to be made between springs 43 and 69. The ratchet wheel 55 has 20 teeth and will rotate the cam C| one half revolution when ve of the bell signals are to be transmitted in succession. The resting position of the ratchet wheel 55 is always one which will restore the switch tongues BI, B2, B4, and B1 to normal. The purpose of switch tongue BI and its associated front contact is to short-circuit the winding of the idle-time relay I6 whenever the bell signal is to be transmitted. Thus, the idle-time relay is automatically rendered ineffective whenever the bell-signal keying device is actuated.

It will be seen from the above that upon actuating the bell-signal keying device, the tongues B2, B4, and B1 are moved to place marking potential on their associated segments of the transmitting distributor ring Rl and this operation is repeated in accordance with the dial fingering for producing the desired number of strokes of the bell at the receiving station.

The receivingapparatus .The receiving apparatus, as arranged for reception of the bell signal, comprises signal distributor rings R5 and R1 and local distributor rings R6 and R8. Ring R1 has applied thereto the marking and spacing impulses of the received code combinations. Under conditions of trafilc signal reception, these code impulses are distributed through the segments to 'l inclusive on distributor ring R5 and thence to selected ones of a set of printer selector magnets P|P1. It will be understood that the signals as received over a wire line or radio channel are caused to actuate a keying relay R9. This relay hasits tongue connected to a receiving ring R1 and its associated contacts kconnected to direct current source terminals of opposite polarity.

In parallel with the selector coils in positions 2, 4, and 1 are relays 12, 14, and 11. As the marking impulses forA the bell signal combination are received in sequence, these relays will be energized. Each relay performs two circuit operations. One is to close a locking circuit for the relays own winding, as by means of the contacts 1i. The other is to close a selective circuit which is only completed when all three of the relays 12, 14, and 11 are actuated. Such a selective circuit includes contacts 13, 15, and 18. In this selective circuit are the source terminals and a magnet 19, the armature lll of which is extended into a clapper for the bell 8| Upon reception of any code signal other than the bell signal, even though one or two of the relays 12, 14, and 11 may be energized, nevertheless, the failure to actuate all three of these relays would result in the bell ringing circuit being kept open. Consequently, the bell is sounded only upon reception of the code elements applied to segments 2, 4, and 1 in the distributor ring R5.

After reception of each bell signal, the brush traversing the distributor rings R6 and RB will pass over segment 8, thereby causing an 8th-pulse relay 82 to be energized. This relay has contacts 83 which are associated with the printer mechanism and which need not be herein considered. The relay 82 also has circuit-breaking contacts 84 which lie in the return circuit between the positive source terminal and the locking contacts 1| in relays 12, 14, and 11. Hence, by this arrangement, relays 12, 14, and 11 become deenergized when the distributor brush passes over segment 8 in ring R6.

It requires the repeated selection of relays 12, 14, and 11 in combination and in accordance with the bell ringing code signal for obtaining repeated strokes of the bell.

In the actuating circuits for each relay 12, 14, and 11, I preferably use resistors 85 for dissipating the energy in the residual fields of these relays.

The various advantages of the combined arrangement of transmitter code signaling device, idle-time signaling device, and auxiliary signaling device will be apparent to those skilled in the art. The particular advantage which is obtained by the use of my invention as compared with the prior art lies in the simplified and more rapid procedure for transmission of bell signals without the use of case shift signals. This advantage is also accompanied by the avoidance of difficulties due to improper printing of traffic signal characters in the upper case when they should be in the lower case, or vice-versa. This advantage will be particularly noted when it is understood that the actuation of the bell-signal keying device does not involve case shifting. Even though tralc signals in the upper case may have been interrupted by the use of the bell code signal, nevertheless, upon restoration of trafilc signaling, the upper case characters will continue to be printed.

By reference to Patent No. 2,183,147, issued December l2, 1939, to J. B. Moore et al., it will be noted that the seven-unit signaling code of their invention is so designed as to permit of automatic error indication wheneverthe signal, as received, is composed of more or less than a xed number of marking elements, usually three. So the bellsignal, as transmitted by the apparatus of my invention is preferably composed of 'three marking elements and four spacing elements. It thus conforms to other code combinations in this respect.

In certain well-known types of telegraph printers, means are provided for preventing the operation of the tape feed mechanism during reception of signals for shift," and unshift, blank, etc. Such means are usually associated with dummy pullbars which are actuated by the main operating bail. These dummy pull-bars are selected in response to the reception of their ap'- propriate signals and cooperate with a so-called fspacing cut-out universal bar for preventing the operation of the space lever. Hence, the tape is not fed forward when "stunt signals are received. In like manner a dummy pull-bar is preferably provided for selection by the bell signal, and this pull-bar serves to prevent the feeding of the tape when sounding the bell signal. A further function of the dummy pull-bar in certain types of printers is to prevent the operation of an error-indicating device. I have not, however, illustrated mechanism for tape fee-:l and mis-selection indicator prevention, since it forms no part of my invention.

Whenever the bell signal becomes mutilated, the receiving printer is caused to print an error symbol as a substitute for'ringing the bell, as will be understood from the fact that the function of the error-indicating device is conventionally performed in response to any departure of the received signals from their normal make- 11p.

Various modifications of my invention will doubtless suggest themselves to those skilled in the art in view of the foregoing description. I do not intend, therefore, to be limited to the particular arrangement of partsas herein disclosed for practicing the invention.

I claim:

1. A signaling device comprising a tape-controlled character-code keyer, an idle-time signal keyer, and a bell-signal keyer, each of said key"- ers having switching means whereby the marking elements of diierent code signals are composed, a transmitter having distributor means for collecting successively different elemental pulses of marking and spacing significance fed thereto in accordance with the operation of said keyers, manipulative means for causing said bell-signal keyer to transmit a bell-signal representing a selected number of bell strokes, the signal for each stroke being confined t0 one operating cycle of said distributor means, and said distributor means being arranged and adapted to complete only one cycle between any two successive bell stroke signals, a receiver for responding to signals initiated by any of said keyers, a plurality of relays individually responsive to different marking elements of a bell-signal, and means including an electromagnetic device, operable upon closing a circult therefore through all of said relays, whereby said selected number of bell strokes is produced.

2. A signaling device according to claim l and including means for causing the character code keyer to be disabled by the idle-time keyer, and means for causing both the character-code keyer and the idle-time keyer to be disabled by the bell-signal keyer,

3. In a typewriting telegraph system, the method of transmitting intelligence and of con- Y panied by case-shift signals, and means for caustrolling a bell having an electromagnetically operable clapper, which comprises transmitting coded intelligence signals the response to which depends upon the transmission of a precedent case-shift signal, transmitting coded bell signals the response to which is independent 0f precedent case-shift signals, and causing the clapper of said bell to respond to the reception of an uninterrupted succession of said bell signals by making a number of clapper strokes equal to the number of vreceived bell signals.

4. Signal transmitting apparatus adapted for use in a synchronous printing telegraph system, comprising a line, a perforated tape-controlled transmitter including means for composing the elements of character signals and case-shift signals. an idle-time keyer, a` bell-signal keyer, cyclically operable means for impressing signals upon said line when codified by said transmitter for message transmission and at other times by a selected one of said keyers, said signals when codied by the transmitter being of duel significance in that they relate to upper and lower case printing characters, and said signals when codified by said keyers being independent of upper and lower case designation, -means enabling said keyers to transmit their signals unaccoming said transmitter and said keyers each to impress signals upon the line at mutually exclusive periods.

5. Apparatus according to c laim 4 and including means for assigning a fixed number of marking elements to each of the signals whether codied by said transmitter or by either of said keyers.

6. Signal receiving apparatus comprising a printing telegraph instrument operable in response to code signals having a uniform number of marking elements and a uniform number of spacing elements, means in said instrument for causing it to respond in one way to character signals which follow the reception of a gure shift" signal, and to respond in a different way to character signals which follow the reception of a letter shift signal, a. bell Stroker, a relay system responsive to the reception of a bell signal combination of marking and spacing elements, said bell signal being of unalterable significance and independent of the transmission of said figure shift` and letter shift" signals, and an operating circuit closeable by said relay system for actuating said bell stroker.

ANDREW L./BROWN.

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