US2086679A - Telegraph system - Google Patents

Description

July 13, 1937. w. T. REA v 2,086,679

TELEGRAPH SYSTEM Filed July 15, 1954 5 Sheets-Sheet 1 I'H" INVENTOR MIREA 3g BY ATTORNEY July 13, 1937. w. T. REA 2,086,679

TELEGRAPH SYSTEM Fiieci July 1:5, 1934 3 sheets-sheet 2 FIG. 2

SPACE //v VEN TOR W. 7'. REA BY July 13, 1937. w. T. REA 2,086,679

TELEGRAPH SYSTEM I Filed July 13, 1954 3 Sheets-Sheet 3 FIG. 6

Ami/ F U "fi II I I filhll [1 III II 11 III mmm RECEIVING AND TRANSMITTING Fla 7 RECEIVING AND TRANSMITTING FACS/MILE TELEGRAPH STATIONS TANSLATINE TELETYPEWR/TER STATIONS 70 APPARATUS 7I/ ACSIMIL TELETVPE CENTRAL CENTRAL I STA TIONS S TA TIONS 70/ r 7// r n- -d -4 70] 702 7,2 7]] INVENTOR I W. 7.' REA ATTORNE Y Patented July 13, 1937 UNITED STATES PATET orrlcs TELEGRAPH SYSTEM Application July 13, 1934, Serial No.- 735,043

Claims.

This invention relates to telegraph printing systems and more particularly to means for translating facsimile telegraph current signal impulses to Baudot permutation telegraph signal impulses.

It is sometimes desirable to interconnect facsimile telegraph sytems with Baudot permutation code telegraph systems so that signals which originate in one system representing symbols may be translated into signals which represents the same symbols in the other telegraph system.

British Patent No. 380,217, September 15, 1932 to W. W. Triggs discloses such systems and means for translatinggroups Baudot code signal im- :pulses representing symbols into facsimile telegraph signal impulses representing the same symbols.

The object of this invention is to provide a device for translating facsimile telegraph signal impulses into Baudot permutation code current impulses.

A further object of this invention is to employ cold-cathode gas-discharge tubes to transfer impulses from one circuit to another circuit. These tubes have the advantage that they do not require a source of power to heat the cathode. In addition they do not require replacement due to cathode failure.

The invention provides a receiving distributor "7 for selecting certain facsimile signal impulses, a

transmitting distributor for transmitting Baudot permutation telegraph code impulses, and gaseous discharge tubes and relays connected between said two distributors. Both the facsimile j and the Baudot telegraph systems may use the start-stop principle for synchronizing the transmitting and receiving distributors. In this case the distributors employed in the translating device of this invention are also provided with start-stop latches and magnets.

This invention provides a novel system and apparatus especially adapted for use in existing facsimile channels employing signaling circuits within the range of voice frequency and over highly perfected modern radio and other voice transmission circuits.

The invention may be more fully understood from the following description when read with reference to the accompanying drawings in 59 which:

Fig. 1 shows diagrammatically the arrangement of apparatus and circuits employed in one embodiment.

Fig. 1A shows a modified circuit in which a hotcathode gaseous discharge tube is employed;

Fig. 2 shows the scanning area allotted to each character in Facsimile printing telegraph systems such as described in my copending application, Serial No. 728,611, filed on June 1, 1934 and issued as Patent 2,015,155 on September 24, 1935 5 together with sub-areas used for translating purposes;

- Figs. 3 and 4 show typical letters in these scanning areas as they normally appear with the subareas used for translating purposes superimposed 10 thereon;

Fig. 5 shows a table of the various combinations of marking and spacing signal impulses in a Baudot code which represents the various letters of the alphabet; 15

Fig. 6 shows the shape of the various letters of the alphabet in relation to the sub-areas used for translating purposes; and

Fig. 7 shows one arrangement of the translating apparatus for interconnecting a facsimile telegraph system with a teletype telegraph system.

In general, the equipment for translating facsimile telegraph signal impulses into groups of telegraph signal impulses of a Baudot code representing the same characters consists of a detector tube, a receiving distributor rotating in synchronism with the scanning device at the sending station, five recording gaseous ionic tubes connected to the plate circuit of the amplifier or detector tube through the receiving. distributor at intervals corresponding to the designated subareas of Fig. 2, five sensitive relays operating from the above ionic or trigger tubes, five locking or recording relays which operate from the sensitive relays, a sending distributor rotating at approximately the same speed as the receiving distributor and a sending relay operated by the sending distributor for repeating marking and spacing signals to the outgoing line.

The terms impulses, signal impulses, and current impulses, as used in this patent application include carrier current and modulated carrier current impulses as Well as direct current impulses.

For the purposes of this description it is assumed that the sending station in a facsimile system is sending one letter at a time such, for example, as described in British Patent 380,217, identified above. Each letter is formed by successive impulses transmitted to the line by a cam arrangement, the design of which, fundamentally, is based on a scanning of the letter in parallel lines; that is, parallel rows of small sub-areas examined in sequence. Since each letter of the ill alphabet and each of the other commonly employed characters is of a distinctive shape, a different arrangement of signal impulses will be produced for each of the letters or characters transmitted. Fig. 3, for instance, shows the shape for the letter A and Fig. 4 the shape for letter K in which the shaded areas outlining the letter represent the successive intervals of time that certain impulses are transmitted to the line.

Referring to Fig. 2, it will be observed that certain definite fixed sub-areas numbered I to 5, 2' to 5 and 2 to 5" are designated on the scanning area allotted to each letter or character. These sub-areas represent the times when one or more of the five recording ionic tubes of Fig. 1 are connected to the incoming line detector. If the shape of the letter being sent is such as to cover any or all of these fixed sub-areas, the corresponding impulses will be registered by the corresponding recording tubes i5l to 255 (see Fig. 1) above mentioned, and will result in the sending distributor transmitting marking and spacing signals to the outgoing line corresponding to the letter occupying these various fixed sub-areas.

An individual receiving channel or line ifll is shown in Fig. l incoming from a telegraph transmitter of the facsimile type, said channel being shown terminating in an amplifier or detector tube H33. However, it is to be understood that tube E83 may be the last tube of a multi-tube amplifier. Since the specific details of such an amplifier form no part of this invention, they have not been shown. The detector Hi3 may be of any well known construction, but preferably is of the vacuum tube typehaving .its grid circuit adjusted in a well known manner so that when no impulses are being received, substantially no current flows in the output circuit of the detector, but when impulses are being sent over the line to the detector by the facsimile transmitter a current flows in the output circuit of the detector.

While this particular description of this invention assumes a facsimile system operating on a start-stop basis, it will be readily understood that it could also be arranged for continuous synchronous operation. The plate M5 of the detector I83 is normally connected to plate battery 56 through resistance I Hi, winding of starting relay I59 and receiving distributor its so that the starting impulse, which always precedes the sending of a character or letter, will operate relay IE9 and cause magnet 52b to release distributor arm I22 for one complete revolution after which it again is held by the latch 52%. The receiving distributor M73 as well as the sending distributor N6 of Fig. l are shown only in schematic form since mechanisms of this kind are well known in printing telegraphy. It will be further understood in connection with said distributors that they are motor driven and that means are provided for accurate control of their speed, or for synchronizing them with the speed of similar distributors in other parts of the systems. Receiving distributor arm l22 when released by start magnet I29 should therefore be thought of as rotating in synchronisrn with the cam shaft of the facsimile transmitter. Similarly, when the distributor arm I38 of the sending distributor H5 is released by start magnet itd, it is assumed to rotate at approximately the same speed as receiving distributor its.

It will be further understood that segments numbered I to 5, 2 to 5' and 2" to 5" on receiving distributor I68 are so disposed that, during the rotation of arm I22, plate I45 of tube N33 is connected to the ionic tubes I5I to- I55 for recording signal impulses receiving from line IQI through the detector I03. The similarly designated sub-areas in Fig. 2 represent more clearly the intervals during which the segments just described are connected to plate detector I93. When a signal is received so that rectified current will flow in the plate circuit of detector tube its as arm I22 passes over any of the segments l to 5, 2 to 5, or 2" to 5", it causes ionic tubes E5I to I55 to break down and. operate the corresponding recording relays S1 to S5 and eventually cause transmitting relay ill to send out marking and spacing signals in accordance with the recording relays that have been operated by the received signals. The several combinations of signal impulses of a Baudot code representing various symbols are shown in Fig. 5.

The operation of translating facsimile signals into Baudot code signals will now be described. Normally the circuit of line IOI terminating in grid Hi2 does not have a source of current connected to it at the sending end. When, however, a character is to be transmitted a short starting pulse of current is sent over the line IIlI causing relay I09 to operate over a circuit, from battery let, through resistance IIIJ, segment IU'I, brushes I95, W5, segment I534 to plate I45 of tube we. Relay I59 in operating energizes start magnet 826 through its make contacts which in turn unlatches arm I22 which then starts to rotate in a counter-clockwise direction and in synchronism with the sending facsimile transmitter. Facsimile systems, as is well known, transmit messages by sending current impulses to the line at intervals depending on the shape of the letter or character to be sent. This is accomplished by a method of scanning in which characters or symbols are divided into any suitable number of sending units of area. Since the receiving distributor I08 of Fig. 1 is arranged to rotate in synchronism with the transmitter, the latter area of Fig. 2 may be assumed to he the same as that for the facsimile transmitter. When, therefore, the letter A is being transmitted, the shaded areas in Fig. 3 actually represent those intervals of time during which a source of alternating or direct current is connected to the line. It will thus be observed that shaded areas in this case actually overlap at least one of the sub-areas 2 to 5, 2 to 5' or 2" to 5" but do not touch the sub-area I which is near the top of vertical strip 30L The letter A therefore will be represented and retransmitted in Baudot code by marking impulses during intervals 2, 3, 4 and 5 or" the code as will later be explained. Another example is found in the letter K shown on the letter area of Fig. 4. In this case the shaded areas overlap at least one of the sub-areas I, 2, l, 2', 4, 2" and 4" but do not overlap any of the sub-areas 5, 5' or 5" which are near the top of vertical strip 492 and near the middle of strips Q55 and 4%, respectively. Neither do they overlap any of the subareas 3, 3 or 3 located at the bottom of vertical strip MI and near the top of strip 483 and middle of strip 494 respectively. The letter K therefore will be represented and retransmitted in Baudot code by marking impulses during the intervals i, 2 and i of the code as will now be explained.

The receiving distributor arm I22, having been I45 of started rotating in synchronism with the fac simile transmitter as previously explained, carries brushes I05 and I06 into momentary contact with segments I3I and I43, respectively. A circuit for relay I44 is thus momentarily established starting from the grounded segment I3I, brushes E05 and I66, segment I43, thence through the Winding of relay I44 to battery. Relay I44, in turn, first operates and then releases. This momentarily disconnects battery III from relays S1 to S5 and associated ionic tubes I5I to I 55. This interrupts the discharges in these tubes and restores them and their associated relays S1 to S5 to normal in case one or more may have been operated during the previous cycle or revolution of arm I22. These tubes and relays are then free to record impulses received from segments I to 5, 2 to 5' and 2" to 5" as the distributor arm I22 continues to rotate.

Assuming the letter A, as shown in Fig. 3, is being translated, signal impulses will not be received from line IOI at the time distributor arm I22 with its brushes passes over segment I so that substantially no current will flow in the plate circuit of detector tube I03 at this time. Ionic tube I5I, therefore, will remain normal and relay S1 will not operate. Arm I 22 with its brushes then moves on over segment 3 at which time no signal impulses are received from line IOI because this segment corresponds to the subarea 3 at bottom of vertical row 302, which is not shaded, as shown in Fig. 3. When arm I22 reaches segment I32, ground on segment I3I is connected through brushes I05 and I06 to segment I32 and thence through relay I33 to battery.,

Operation of relay I 33 first opens ground at its armature from its back contact, thus opening the operating and locking circuits of relays T1 to T5 which causes them to restore to normal. Relay I33 at, its front contact connects ground to start magnet I34 of sending distributor II6 which causes it to attract its armature I28 and unlatch distributor arm I36. Since the speeds of the two distributors are approximately the same it will be evident that distributor arm I36 will trail behind distributor arm I22 by more than a half revolution, thus giving arm I22 with its brushes time to pass over the segments of distributor I08 before distributor arm I36 passes over the related segments of distributor II 6. Upon first moving off normal, arm I36 with its brushes H3 and I I 4 immediately breaks a circuit from ground, connected to segment II2, through segment H5 and relay II I to battery. Relay 1, in releasing, substitutes a negative for the positive potential connected to line II9 which negative potential serves as a spacing or start signal or impulse. While arm I36 is moving over segment I6I to transmit the start signal impulse, further movement of arm I 22 will be described.

Receiving distributor arm I22 in moving past segment I32 releases relay I33 which in turn restores ground to the operating and locking circuits of recording relays T1 to T5 and also opens the circuit starting magnet I34. The latch I28 pivoted at I29 on magnet I34 is thus restored to its normal position by spring I 35 so as to stop rotation of arm I36 at the end of one revolution. Upon further movement of arm I22, brush I 26 passes over segment 2 thus closing the circuit to ionic tube 552 from plate I of vacuum tube I03. Signal impulses are not received at this time during the transmission of letter A because the subareas 2 in vertical column 303 of Fig. 3 are not shaded by the letter A. Ionic tube I 52, therefore,

does not break down. A further movement of arm I22 brings brush I26 into contact with segment 5 thus completing a circuit for ionic tube I traced from the plate I45 of vacuum tube I03, ring I46'of'distributor I08, brushes I25 and I26, segment 5 and resistance I58 to tube I55. Again referring to Fig. 3, it will be observed that sub-area 5 is shaded by letter A which indicates that signal impulses are received, at this moment, from line IOI. Due to the action of vacuum tube I03, current will flow in its plate circuit from grounded battery III through contacts of relay I44, winding of relay S5, resistances I63 and I58, segment 5, brushes I26 and I25, and segment or ring I46 of distributor I08 to the plate I45 of tube I03. This current flowing through resistance I63 will cause a potential 'drop across it to ionize the gas in the tube I55.

These tubes I5I to I55 are of a cold-cathode gas-filled type having three electrodes I41, I48 and I49 two of which I48 and I 49 are coated or activated so they will more readily emit electrons in an electric field without the application of heat. The tubes are so constructed that it requires a higher potential to start a discharge or to ionize the gas surrounding these electrodes than it does to maintain the discharge. In addition, these elements are so constructed and assembled that it requires a higher potential between elements I41 and I49 to initiate a discharge than between elements I41 and I48. However, after a discharge is started between elements M! and I48, it requires a much lower potential between elements I41 and I49 to start and maintain a discharge therebetween. In addition, once a discharge is started between elements I41 and I49, it is not affected by the discharge or potential between elements I41 and I48. By connecting elements I4! and I48 to an input circuit and elements I4! and I49 to an output circuit, impulses may be repeated from the input circuit to the output circuit.

Thus when a discharge has started between electrodes I41 and I48, the potential between electrodes I41 and I49 is sufficiently high to start a discharge between them. The currents through these discharges operate and hold relay S5 operated on a circuit traced from positive battery III, normal contact on relay I44, winding of relay S5, resistance I51 and electrode I 47 of tube !55 to ground connected to electrode I43. Resistance I5! is provided to limit the current through tube and associated relay. Relay S5, in operating, causes recording relay T5 to operate and prepare a circuit from battery through relay II1 to segment I4I on sending distributor II6.

Receiving distributor arm I22 continues to move until brush I26 contacts with segment 2'. According to Fig. 3 this sub-area located in vertical strip 304 is shaded by letter A indicating that a signal impulse is received from line IOI at this time. Ionic tube l52 which is connected to segment 2' breaks down causing relays S2 and T2 to operate as described in preceding paragraph for relays S5 and T5. A further movement of arm I22 brings brush 326 into contact with segment 4 which in like manner causes signal impulses from line IOI at this time to break down ionic tube I54 and operate relays S4 and T4.

While the movement of receiving distributor arm I22 has taken place as described in the above two paragraphs, the sending distributor arm l35 has been passing over segment I6I causing relay II! to release and send a start signal of negative pulse on line H after respective segments are in an operated position.

As previously stated distributor arm i256 trails behind distributor arm i221. While arm 11 36 continues to pass over segment it? further movement of arm i222 will be described.

Brush EZE on distributor arm 522 now comes in contact with segment 3'. According to Fig. 3 a portion of this sub-area located near the top of vertical strip 36% is shaded by the letter A indicating a signal impulse is received from line iiil at this moment. As previously described in connection with tube 555 the gas-filled tube E53 is caused to break down and operate relays S3 and T3. The arm moving further brings brush liiti into contact with segment 5 and brush lot in contact with segment 2" which would cause tubes 5'52 and $155 to break down but as has been described they already have been broken down. Similarly these same brushes contact next with segments 3 and i respectively which also would cause tube 553 and i5 5- to break down but as has been shown these too have previously been broken down, when distributor arm it? passed over segments '3 and 3. On further rotation of i222 brush tilt contacts first with segment d and then with segment 5. According to Fig. 3 signal impulses are not received from line lti at these times, but the associated tubes and E55 having previously been broken down, remain so until released by operation of relay its during the transmission of a succeeding letter or character.

The complete rotation of distributor arm l2? has, in the manner described above, caused ionic tubes i532, lot, i5 5 and 555 to break down thereby causing the operation of the recording relays T2, T3, T4 and T5. The loclnng circuit for these relays is controlled by relay 533. Relay M33 must, therefore, remain normal until arm H36 has carried brush lit over all the segments of distributor lib in order to prevent the release of these recording relays T1 to T5 before the distributor arm Hill has finished transmitting the complete signal combination.

Distributor arm ltt in passing over segment 631i fails to operate relay llll because relay T1 had not operated thus holding the circuit for relay ill open and can lng a negative spacing signal impulse to be sent out on line H9. The further movement of arm i256 connects ground through its brushes M3 and Hi l to segments E38, itii, t lt and i 'll in succession. Since relays T2, T3, T4 and T5 are operated as previously described, the relay ill will operate and transmit a positive marking signal to line H?) during each of the four periods, which together with the previous period corresponding to segment E37, form a fiveunit Baudot code combination corresponding to the letter A which was sent out on line Hit by a facsimile transmitter.

The combinations of marking signal impulses representing the other letters in the alphabet are shown by an X mark in the table in Fig. 5. When distributor arm causes brush 555% to connect with segment MS, a circuit is closed from the ground connected to ring lit directly to the winding of relay i ll thus always operating relay Iii to send a positive marking signal imthe Baudot signals have aosacva been sent. commonly serves as a stop signal. The arm Mb upon returning to normal strikes the latch E23, is stopped and prevented from rotating any further.

Another example of the manner in which a letter in the facsimile system is translated into a Baudot code signal representing the same letter is illustrated in Fig. 4 which shows the facsimile letter K. In this case it will be observed that subarea i in vertical strip ist is shaded by the letter K. Likewise sub-area 2 and 2' in strips 402 and dill and subarea i in strip 403. The other fixed sub-areas do not fall within the area of the letter K so that as indicated in Fig. 5 the letter K in facsimile code is translated into Baudot code as marking signal impulses for the first, second and fourth elements of the Baudot code employed, In this manner the various letters or other characters occupy one or more of the fixed sub-areas giving a distinctive Baudot permutation code combination for each letter or other character as shown in 6. Here the various letters of the alphabet are shown on the letter space and cover the various sub-areas in accordance with table 5.

Fig. 7 shows one manner in which this invention may be used to interconnect a facsimile telegraph system and a teletype telegraph system. Here Till represents facsimile telegraph stations which may either send or receive and record facsimile telegraph si nals or they may both send 9 and receive and record these signals. These sta tions may be connected to central stations 102 by telegraph lines or channels. These central stations may include switching and testing apparatus and circuits. The teletype system is shown in similar form in which 'lli represents the receiving and transmitting stations while H2 represents the central stations. In addition these stations may be in a broadcast system, a

news system or supplied to individual subscribers or some of them may belong to each of these systems.

The translating apparatus is shown to comprise three general elements Hi3, Mi l and 165. The translating device for changing teletype signals into facsimile signals is represented by ill? and may be similar to the arrangement shown in British Fatent 380,217, September 15, 1932 granted to W. W. Triggs. The translating apparatus (such as shown in Fig. 1) for changing facsimile telegraph signals into teletype code signals is represented by "W5. A lockout device 104 is provided to prevent the operation of either 103 or "m5 during the operation of the other of these devices so that there can be no interference between them.

Thus, in the arrangement shown in Fig. 7, signals which originate at any of the stations ml and ll i of either system may be received and recorded by any or all of the other stations of either or both systems.

It will be obvious that the general principles thus disclosed may be embodied in other organizations widely different from those illustrated, without departing from the spirit of the invention as defined in the following claims.

For example, Fig. 1A shows one circuit by which some or all of the cold-cathode tubes GM to I55 may be replaced by hot-cathode tubes. Here the primary '5' of input transformer H5 is connected to the distributor segments and to battery H6 which serves as the B battery for tube 5&3. The secondary S of this transformer I is connected to the grid lf il of the hot-cathode gas-discharge tube I78 and to battery ll'l which provides the bias potential of the grid lSt of this tube. The cathode H82 is heated in any suitable manner such as by current from battery N32. The operation of this circuit and tube is similar to that described for tubes 85! to I and their associated circuits. If a signal impulse is being received from line lei when the primary P of transformer H5 is connected to the plate of tube 5%, it will be transmitted to the grid its of tube H8 and oppose the bias potential of battery Hi. This causes the tube to break down and starta discharge therethreugh. This dischargewill continue unaffected by the grid potential until the plate circuit through current regulating or limiting resistance M3 and the associated S relay to battery lil is interrupted by relay l l l. In this manner impulses received from line Hill are amplified, selected, distributed and stored by these tubes and associated relays until after being retransmitted by distributor lit. Condensers I85 and i335 may be provided to prevent stray fields from affecting the operation of tube lit.

What is claimed is:

1. In combination, a first printing telegraph system comprising a plurality of telegraph stations each having telegraph transmitting and receiving appar tus for transmitting and receiving permutation code combinations of telegraph signal impulses representing symbols, and telegraph communication channels connected between said stations, a second printiir telegraph system comprising a plurality of stations having facsimile printing telegraph transmitting and receiving apparatus, and telegraph communication channels connected between said stations, translating apparatus connected between said systems comprising printing telegraph transmitting and receiving apparatus for transmitting and receiving permutation code combinations of telegraph signal impulses, a first communication channel connecting said apparatus to said first system, facsimile telegraph transmitting and receiving apparatus for transmitting and receiving facsimile telegraph signal impulses, a second tele graph communication channel connecting said facsimile apparatus to said second telegraph system, and translating means operatively con nected between the receiving apparatus connected to each of said telegraph communication channels and the transmitting apparatus connected to the other of said telegraph communication channels whereby symbols transmitted'in either of said systems may be properly recorded in the other system.

2. A translating system comprising an incoming telegraph line, a facsimile telegraph receiving apparatus connected to said line, selective means operatively connected to said apparatus for selecting only a certain portion of certain of the impulses received over said telegraph line, storing means controlled by said selective means for storing said selected portions of said selected impulses, a telegraph transmitting device comprising permutation members, an operative connection between said permutation members and said storing devices, and an outgoing line connected to said telegraph transmitting device.

3. In combination, a teletypewriter communication system comprising a plurality of telegraph 1 stations connected together by communication circuits and start-stop telegraph transmitting and receiving apparatus employing permutation code combinations of telegraph signal impulses for 1 representing symbols connectable to said teletransmitting and receiving apparatus, and an operative connection between said facsimile transmitting and receiving apparatus and said teletypewriter transmitting and receiving apparatus whereby telegraph signal impulses originating in either system representing a symbol will cause the corresponding symbol to be recorded in both of said systems.

4. A telegraph translating device comprising an incoming line, start-stop facsimile distributors connected thereto, means responsive to facsimile telegraph signal impulses received over said line for starting said distributor, a start-stop permutation code teletypewriter transmitting distributor, translating means operatively connected between said facsimile start-stop distributor and said permutation code transmitting distributor and means for starting said transmitting distributor when facsimile telegraph signal impulses are received from said incoming line.

5. In a telegraph system, an incoming line, a receiving device connected thereto for receiving telegraph signal impulse-s, a start-stop distributor operatively connected thereto for selecting a few of said impulses, means responsive to received impulses for starting said distributor, a plurality of gas-filled ionic tubes operatively connected to said distributor for storing said selected impulses, additional storing means connected to said gasfilled ionic tubes, a start-stop transmitting distributor for transmitting permutation code groups of telegraph signal impulses, an outgoing line connected thereto, means for starting said transmitting distributor when signals are received from said incoming line, and means operatively connected to said first distributor for controlling said gas-filled ionic tubes and said storing means.

WILTON TREAT REA.

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