US2052677A - Telegraph system and apparatus - Google Patents

Description

Sept. 1, 1936. A. E. THOMPSON Er AL TELEGRAPH SYSTEM AND APPARATUS Filed April 18, 1935 2 SheetS-Sheet 1 Fig. 1.

Sept. 1, 1936.

A. E. THOMPSON ET AL TELEGRAPH SYSTEM AND wmnnus Filed April 18, 1955 2 Sheets-Sheet 2 Fig.2.

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Patented Sept. 1, 1936 TELEGRAPH SYSTEM AND APPARATUS Alfred Edward Thompson and Reginald Dennis Salmon, Croydon, England, asslgnors to Creed 8; Company, Limited, Croydon, England Application April is,

1935, Serial No. 16,944

In Great Britain April 20, 1934 '1 Claim.

This invention relates to telegraph systems and apparatus therefor.

The object of the invention is to provide a telegraph system and apparatus which affords the maximum possible safeguard against the incorrect recording of a character which is correctly sent.

According to the invention a telegraph system is provided in which each code combination of signal impulses representing a character is transmitted a plurality of times and the character is recorded only if all the corresponding received combinations are identical.

It has previously been proposed, in type printing telegraph systems intended for use over radio links, to transmit each code combination of signal impulses representing a character a plurality of times, and to compare automatically the different received combinations, but in such systems the printing of a character took place in accordance with the resultant of the different combinations as received. This was intended to guard against interference due to atmospherics, and the assumption was made that the effects thereof would be confined to inserting marking impulses. In consequence a character was printed corresponding to a code combination in which the marking elements were those common to all the combinations received, whilst the remaining elements were spacing elements.

According to a further feature of the invention we provide a telegraph receiving and recording arrangement adapted to receive a plurality of separate transmissions each intended to represent the same character in, which the record of the character is made only if all the receptions are the same.

A further feature of the invention is a type printing telegraph receiver which receives each code combination a plurality of times and makes a selection of a character to be printed in response to each such code combination, but only causes the character to be printed if the selections are identical for each such code combination.

A further feature of the invention is a type printing telegraph receiver adapted to receive a plurality of code combinations each intended to be the sameand which will, if they are the same, make a distinguishing mark on the paper to denote that fact. 7

The invention will be better understood from the description of the accompanying drawings; in which Fig. 1 shows diagrammatically the essential parts of aprinting telegraph receiving apparatus which will indicate errors in the code combinations received, whilst Fig. 2 shows diagrammatically a printing telegraph receiving apparatus which "will indicate errors occurring either in the code combinations received over the line, or in the selecting operations performed as a result of the receipt of such combinations.

A telegraph transmitter which cooperates with either the receiving apparatus shown in Fig. 1 or that shown in Fig. 2 transmits code combinations representing characters to be printed, or operations to be performed (such as shift and unshift signals) 'by means of the well known five unit code, and moreover transmits each code combination twice in succession.

In the case of a transmitter operating a transmitting contact or contacts by means of cams, in a combination determined by the key of a key- 20 board that is depressed, or the perforations in a tape, this can be effected by duplicating the usual cams on the rotating transmitter shaft so that these cams effect the sending of the start signal, the elements of the code combination and the stop 25 signal twice over for one revolution of the cam shaft. Equivalent arrangements can be provided in the case of transmitters making use of distributors by which a series of contacts is connected in succession to the line.

Figure 1 represents diagrammatically type prmting telegraph apparatus in which a distributor arm ii is mounted on a shaft 25. This shaft is normally held stationary by an armature l2 common to two electromagnets l3 and 24 engaging with the arm i I. When the energization of either magnet unlatches the arm I I, the shaft 25 is driven through a friction clutch from a motor (not shown) in well known manner.

The magnet I3 is connected to contact i of the distributor and in its position of rest the brush arm i l connects contact I to the continuous ring 8 which in turn is connected to the line L. During its rotation the brush arm ll connects ring 8 successively with contacts 2 to I and then with 45 contact i on which it is arrested until magnet I 3 V or magnet 24 is energized.

Mounted upon shaft 25 is a gear wheel M which meshes with a stepdown ratio of 1:2 with a gear wheel [5 on another shaft 28, so that shaft 28 is driven at half the speed of shaft 25. Mounted on shaft 28 are two cams l6 and i1. Cam l6 operates a grounded switch am Hi so that it is pressed against its upper contact during the first half of the revolution of the cam and against the lower contact during the second half of the revolution of the cam. A bell crank lever 22 is held by a spring 21 against cam II which in normal driven through gearing having a large step down" ratio from the motor shaft.

Contacts 33 are in the circuit of magnet 25, and

are adapted to be closed when lever 22 is moved to the right.

Contacts 2, 3, 4, 5 and 6 of the distributor are connected to one side of the windings of polarized relays A, B, C, D and E and also to one side of the winding of polarized relays H, J, K, M and N. The other side of the winding of relays A, B, C, D and E is connected to the upper contact of switch l8, whilst the other side of the windings of relays H, J, K, M and N is connected to the lower contact of switch l8.

Contact I on the distributor is connected to one side of the windings of a relay ST, the other side printer serve to cause the selection of a character to be printed or an operation to be performed according to the combination in which they are energized. The other terminals of these magnets are connected to the respective marking contacts of relays H, J, K, M and N. The spacing contacts of relays A, B, C, D and E are connected to the respective spacing contacts of relays H, J, K, M and N through resistance 1' equal to the resistance of the respective magnets A, B, C, D' and E. The armature a of the relay A is connected to the lower contact of switch I8, the armature b of relay B is connected to the armature c of relay C; the armature d of relay D to armature e of relay E; the armatures of relays K and M are connected together, as are those of relays H and J. An error relay ER is connected through normally closed contacts sti of the relay S1 to contact"! of the distributor, the other side of the relay ER. being connected to the lower contact of switch l8.

A second pair of contacts st2 of relay ST when in operated position close the circuit of a magnet F for initiating the printing of a character whilst contacts erl of the relay ER close the circuit of an error magnet G which raises a mask between the type and the platen so that an error mark is made on the paper instead of the character, whilst contacts er2 connected in parallel with contacts st2 operate the printing magnet.

The operation of the apparatus is as follows, double working being assumed.

A current start signal received energizes magnet |3 to remove the latch holding shaft 25 and arm against rotation. The switch I8 is against its upper contact and remains so during the first rotation of shaft 25 and brush successively connects the line to relays A, B, C, D and E and energizes them according to the code combination received. The armature of these relays are retained in the position to which Brush they are moved in well known manner. The passage of brush over contact of the distributor will at this time be ineflective to energize either relay ST, or relay ER. since the switch I8 is on its upper contact. Brush U will come momentarily to rest, on contact l' of the distributor since magnet I8 is now de-energized. On reenergization of magnet l3 by the start signal for the second transmission of the code combination,

shaft 25 and brush II will again commence to ated by the marking stop signal received over the line as brush passes over contact I of the distributor, in a circuit over the armatures n, e, d, m, k, c, b, 1, h, a, to the lower contact of switch l8 and ground. Such of the magnets A, B, C, D, E will be included in this circuit as are selected by the armatures which rest on their marking contacts. Relay ST operates more quickly than relay ER so that contacts stl will open before relay ER can operate. Contacts st2 close the circuit of magnet F which energizes to initiate the operation of the selection of a character or anoperation to be performed.

The general arrangements of the type printing mechanism may be similar to that of any well known five magnet printer, in which printing takes place during the same cycle as that in which the character is received the magnets A, B, C, D and E being the magnets for moving the permutation bars and the magnet F the magnet which trips the printing operating shaft.

If, however, the second code combination received does not correspond with the first the armatures a, b, c, d and e ori the one hand and h, j, k, m and n on the other hand will not correspond. On the passage of the brush of arm over contact I of the distributor, there will thus be no circuit for the relay ST, but a circuit will be completed over contacts stl in unoperated position, relay ER to the lower contacts of switch l8 and ground. Relay ER operates in this circuit at its contacts er|, it operates the error magnet ER to raise a mask into typing position and at contacts e12 operates the printing magnet F to initiate the printing operation.

An arrangement is provided to ensure that the first code combination of each pair is always distributed to relays A, B, C, D and E. Should the brush H and shaft 25 stop in such position that the preceding code combination has been distributed to these relays, so that at the next revolution switch l8 will be against its lower contact, shaft 28 will have performed half a revolution only and the recess in cam will be in position to allow the end of lever 22 to drop therein under pressure of spring 21. This will not occur during a momentary stop of cam H for the pawl on the end of lever 2| will be engaged with a tooth on ratchet wheel 20 whichwill hold lever 22 to the left against spring 21. After an interval the wheel 20, rotating slowly in a clockwise direction will allow levers 2| and 22 to be drawn by spring 21 to the right to operate contacts 33 and so close the circuit of magnet 24. Magnet 24 attracts the armature I2 and so trips arm II to allow shaft 25 carrying that arm to execute another rotation. I v

The delayed action of the closing of contacts 33 as described is accomplished by the arrangement disclosed and claimed in application No. 339/35. 1

The arrangement shown in Fig. 1 may be adapted for single current working in the line by conmeeting the line to a line relay, the front and back contacts of which connect the required polarity to the ring 8 of the distributor.

Figure 2 shows diagrammatically type printing telegraph receiving apparatus in which errors due to the receiving apparatus as well as errors due to the line conditions will result in the printing of an error mark instead of a normal character.

The rectangle PI represents a-type printing telegraph receiver, which may be of the kind described in British specification 228,842, R1 being the single receiving magnet thereof. The type wheel of such apparatus is replaced by a distributor arrangement I3, 5 so that .instead of the type wheel being brought into position to print a character, a disc 6 provided with a contact for each character on the type wheel is brought into position to effect connection of the selected contact with a brush I3 connected to ound.

P2 represents also a type printing receiver as described in British specification 228,842 provided with the usual type wheel I1, and also upon the same shaft with a disc I having a contact for each position of the type wheel. When the type wheel I1 is in printing position a brush connects the contact corresponding to the character that is in printing position to one contact of a pair of contacts ID. A cable l2 connects corresponding contacts on discs 6 and I with one another.

Upon the cam shaft 20 of receiver PI there is provided, in addition to the cams usually present, a cam CI cut so-that towards the end of each revolution contacts 3 are operated though these 1 contacts are open with the shaft in normal position. A second cam C5 is also provided which in normal position allows a lever to move under the action of a spring to close contacts 5, and in all other positions moves the lever to allow these contacts to open, but this lever is also controlled by a delay action device so that it does not move to close contacts 5 until after the lapse of a predetermined time.

The cam shaft 2! of receiver P2 is provided with three additional cams C2, C3 and C4. Cam C2 is cut so that towards the end of each revolution contacts 4 are actuated. Cam C4 is cut so that it operates contacts I!) immediately after the received combination has been set up on the receiver. Cam C3 is cut to operate contacts I5 immediately after contacts I0 have been operated by cam C4 and whilst contacts III are still closed.

The type printing receiver P2 is further modified by omission of the cam which usually effects the movement of the printing hammer, by the provision of a magnet F for operation of such hammer and by provision of an error magnet ER, the armature of which, when operated, makes a distinctive mark upon the paper just above the normal printing position. The magnet F is connected in a circuit including a relay 9, contacts III and the brush which moves over the contacts on disc I. Magnet ER is connected to contacts I5 operated by cam C3 and through these contacts when closed, and normally closed contacts of relay 9 to ground.

The line L is connected to a switch arm S which is normally in position shown to connect line L to relay R1 of the printer PI In this position the arm S lies against the armature of a relay I the circuit of which is adapted to be completed by contacts 3. In the alternative position arm S lies against the armature of a relay 2 adapted to be operated by either contacts 4 or contacts 5 which are in parallel. The arm S is held in the position to which it was last moved by a jockey roller or similar device.

The operation of the arrangement is as follows: Switch arm S in normal position connects the line L to relay R1 of printer PI. The first code combination received is therefore received by relay R1 which successively starts up the shaft of printerPI and controls the selection of a particular position of the disc 6 representing the character.

During the stop interval after the receipt of the code combination, cam CI operates contacts 3, which energize relay I. The armature of this relay pushes the switch arm S into position to connect the line L with the relay R2 of printer P2. The code combination sent a second time is accordingly received by relay R: which trips the shaft of printer P2 and controls the positioning of disc I and typewheel II in accordance with the character represented by this second code combination.

Immediately after disc I and typewheel II have been brought into position contacts C4 are closed followed immediatelyby closure of contacts C3. If the disc I and typewheel I! have been brought to a position corresponding to that in which disc 6 of printer PI was brought, closure of contacts III by cam C4 closes a circuit for the printer magnet F in series with relay 9 through contacts C4, brush II and contact'of disc I, corresponding contact of disc 6, brush I3 and ground. Magnet F operates to print the character selected, and relay 9 opens its contacts to prevent any operation of magnet ER. If, however, disc 'I and typewheel II have been brought to a position which does not correspond to the position of disc 6, there will be no circuit for the printer magnet F. On the closure of contacts I5 by cam C3 the error magnet ER is energized and makes a characteristic mark on the paper which indicates an error. Towards the close of the revolution of the cam shaft 2| of printer P2 contacts 4 are operated to close the circuit of magnet 2, which restores switch arm S to the position shown.

If through any cause printer PI comes to rest and printer P2 not be operated thereafter cam C5 will operate in normal position of printer PI to free the lever which acts upon contacts 5.

This lever, as stated above, is subject to a delay action device which does not free it to act upon contacts 5 until after the lapse of a predetermined time. After the lapse of this time contacts 5 are closed to energize magnet 2 and restore the position of switch arm S so that for the next message to be received, the first code combination will be received upon printer PI.

It will be understood that contacts are provided upon discs 6 and I in the positions to which such discs are moved when each corresponding code combination represents an operation to be will be actuated, but as a blank type bar on typewheel !I is then in printing position no mark will be made upon the paper.

It will also be clear that if disc 8 be set to a position representing a character and disc I be set to position representing case shift, the case shift will be performed on printer P2, since this is performed solely by the selecting mechanism, but magnet ER will also be operated to make an error mark upon the paper.

What is claimed is:

1. In a telegraph system, a signalling line a transmitter connected to said line and arranged to transmit each signal code combination a plu-- rality of times, a receiver connected to said line, means in said receiver for storing each of said signal code combinations as received, and means for printing a character operative only if all of said signal code combinations are identical.

2. In a telegraph system, a signalling line, means connected to said line for transmitting each signal for the same character a plurality of times in immediate succession, means also connected to said line for receiving and storing said signals, means for printing the character represented by said signals operative only if all said signals are identical.

3. In combination, impulse receiving means, a plurality of impulse storage means each comprising means for storing a combination of sig" nals representing a character, control means for transferring successive combinations of signals to separate storage means, means for comparing the condition of said storage means, and means actuated by an identical condition of all said storage means for printing the character represented by the identical stored combinations.

4. In combination, impulse receiving means, a plurality of impulse storage means each comprising means for storing a combination of signals representing a character, control means for transferring successive combinations of signals to separate storage means, and for determining a printing operation at the end of the distribution to all the storage means, means for causing an invariable character to be printed, and means operative by an identical condition of all said storage means for preventing the printing of said} invariable character and determining the printing of a variable character dependent upon said identical condition.

5. In combination, impulse receiving means, a plurality of impulse storage means, each comprising means for storing a combination of signals representing a character and for bringing indicating means into a position representing said character, control means for transferring successive combinations of signals to separate ones of said impulse storage means, means controlled by the position of all said indicating means for printing the character represented by the position of one of them.

6. In combination, impulse receiving means, a plurality of impulse storage means each comprising means for storing a combination of signals representing a character, control means for transferring successive combinations of signals each representing a character to separate storage means, means for comparing the combination of signals as stored in said storage means, and means actuated by an identical condition of all said storage means for printing the character represented by the identical stored combinations.

7. A telegraph receiving system comprising a first and a second set of relays each set comprising a relay for each element of a code combination representing a character, means for distributing successive sets oi elements each representing a character to the two sets of relays, means for retainingthe armatures of said relays in the positions into which they were last actuated, a magnet for printing an error mark, a circuit closed on the receipt of two successive code combinations for initiating a printing operation, means for causing an error mark to be printed, a circuit closed over the armatures of both sets of relays in corresponding positions, and a relay in said last mentioned circuit for causing said printing operation to be effective to print the character stored in both sets of relays and for preventing the printing of an error mark.

ALFRED EDWARD THOMPSON. REGINALD DENNIS SALMON.

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