Patent GB-780001-A (GB)
Title: Improvements in code converting arrangements for telegraph systems
Inventor: SNIJDERS ANTONIE
IPC: H03M5/00
Filed: 1952-07-09
Abstract: 780,001. Type-printing telegraphy. STAATSBEDRIJF DER POSTERIJEN, TELEGRAFIE EN TELEFONIE. July 9, 1952 [July 12, 1951], No. 17359/52. Addition to 680,798. Class 40(3). In a code converter arrangement for a telegraph system for converting signals having one plurality of elements into signals having a different plurality of elements and in which each of the signal elements of the input code is applied by two-way switch members to input conductors providing a selective connection to individual intermediate conductors each of which is selectively connected to output conductors equal in number to that of the elements of the converted code, each intermediate conductor includes a group of at least two rectifiers connected in series back-to-back, i.e. cathode to cathode, or anode to anode, the free terminals of one or more of the rectifiers of a group being connected respectively to one or more of the input conductors and the free terminal of another rectifier of the group associated with the respective intermediate conductor being connected to an output conductor determined by the nature, mark or space, of the respective element in the converted code. In the arrangement shown in Figs. 1a, 1b 1c, which is generally similar to that described in the parent Specification, the five-unit code to be transformed is set up on the armatures I ... V of five relays which are controlled by a transmitter and selectively connect via resistors 225 ... 234 earth terminal 249 or negative battery 248 to five conductors a . . . e each connected to sixteen rectifiers 33 . . . 48 (Group I<SP>1</SP>), 49 ... 64 (Group II<SP>1</SP>) ... 97 ... 112 (Group V<SP>1</SP>), or to conductors a<SP>1</SP> ... e<SP>1</SP> individually associated with groups I<SP>11</SP> . . . V<SP>11</SP> of rectifiers 113 ... 128, 129 ... 144, ... 177... 192. The rectifiers of the various groups are interconnected in different ways with intermediate conductors 1 ... 32-for example, rectifiers 97-112 of group V<SP>1</SP> are connected to conductors 1 ... 16 and rectifiers 177 ... 192 of group V<SP>11</SP> are connected to conductors 17 ... 32, and the arrangement is such that for each of the thirtytwo possible combinations of the contact members I ... V, an earth connection is applied to one only of the intermediate conductors 1 ... 32. The conductor 1 may, for example, be selected by the all-marking five-unit combination. The output ends of each of the conductors 1 ... 32 are connected via three rectifiers, such as 251, 252, 253 for conductor 1, to appropriate conductors, the second, third and seventh as shown, of the group of seven conductors 238, corresponding to the 7-unit code, and which are connected in sequence by rotating contact members 239 ... 245 to the grid of a valve 246 normally biased negatively by a battery 357. The rectifiers are arranged and operated as switching circuits as described in Specification 780,002, [Group XL (c)]. The earth potential applied at the output of the conductor 1 over rectifiers 251, 252, 253 renders the valve 246 conducting during the 2nd, 3rd and 7th element periods so that the output relay OR is operated for those intervals and produces marks for the 2nd, 3rd and 7th elements of the 7-unit code, with the result that the all-marking 5-unit code combination is converted into space, mark, mark, space, space, space, mark. The three spare signals in the 7-unit equal-ratio code may be derived by operation of the switches S1, S2, S3 which directly connect earth to the associated intermediate conductor 235, 236, 237. The operation, for example, of switch S3 connects earth to conductor 237 and rectifiers 353, 354, 355 so that the valve 246 is rendered conducting in the third, fourth and seventh time intervals to produce a 7-unit service signal having marks for its third, fourth and seventh elements. In a modification, Figs. 2a and 2b, using a smaller number of rectifiers than required by the arrangement shown in Figs. 1a, 1b 1c, a number of signals in the 5-unit code, viz. those with one, two and three marks are transformed without loss of identity, directly to the 7-unit signals by prefixing a two-element indicator group formed by mark mark, space mark, and space space, whilst for the remaining seven signals of the 5-unit code comprising five signals with four marks, the all-mark and the all-space signals the indicator group mark space is used with 5-unit code combinations having two marks. The remaining three signals of the 5-unit code with two marks are used with the indicator group mark space to produce the three service signals. As indicated in Fig. 2a the 5-unit signals are applied to the inputs 1 . . . 5 of trigger devices T1 . . . T5, which are preferably as described in Specification 780,003, [Group XL (c)], and which produce corresponding pulses at the upper right-hand terminals t<SP>1</SP>1 . . . t<SP>1</SP>5 and inverted outputs at the upper left-hand terminals t<SP>11</SP>1 . . . t<SP>11</SP>5 which are connected selectively to five pairs of conductors 10 and corresponding rectifiers to intermediate conductors 11 ... 30 and five other conductors, not specifically shown, for some of the 5-unit signals having three marks. As indicated for the combination + - - - -, a path is opened via rectifiers 1<SP>1</SP> . . . 5<SP>1</SP> to conductor 11 connected by two further back-to-back rectifiers 6<SP>1</SP>, 7<SP>1</SP> to the first two conductors of the seven conductors 7 on which the corresponding 7-unit code appears and is fed to the inputs of seven trigger devices I ... VII. Also from the rectifiers 1<SP>1</SP> . . . 5<SP>1</SP> a connection extends via conductor 1 to conductor 26 which applies a mark to the third of the conductors 7 so that the equivalent 7-unit signal is + + +----. . For a signal, such as + + - - -, the rectifiers open a path to conductor 16 setting up the group - + and via conductors 26, 27 marks are applied to the 3rd and 4th conductors 7 so that the 7-unit signal is - + + + - - -. For a signal having three marks, e.g. + + - + -, there is no connection to the first and second conductors of conductors 7 so that the indicator group is - -, but via the outputs of triggers T1 ... T5, pulses are applied to conductors 26, 27, 29, 30 so that the 7-unit signal is - - + + - + -. In the cases of the 5-unit signals, having four marks, five marks and no marks, connections are established via the groups of rectifiers to the points 31 ... 37 at which connections are established to two selected conductors, e.g. 3rd and 6th for the point 31. Also a connection is established through a rectifier of group 8 to the input of a trigger A which provides a mark on the first conductor so that the indicator group is + -. The three service signals S1 S2, S3 are selected for transmission by codes + -, - +, + + applied to the inputs Xo, Yo of triggers Xr, Yr, any of these code combinations producing a pulse from rectifiers p, q which over conductor 9 operates a trigger B producing at point z a negative pulse which renders ineffective the circuits for converting the 5-unit code signals and also a positive impulse at point x which operates the trigger A to apply a mark to the first of the seven conductors 7. The signal selecting code selects the respective rectifier group rs, r<SP>1</SP>s<SP>1</SP> or r<SP>11</SP>s<SP>11</SP> so that over conductors 38, 39, 40 marks are added respectively in the 3rd and 7th, 4th and 5th, 5th and 6th element positions of the 7-unit code. The arrangement, Figs. 3a, 3b (not shown), for transforming the 7-unit code to the corresponding 5-unit code operates in a manner generally similar to that described in connection with Figs. 2a, 2b, the 5-unit code being obtained directly without change when the first two elements of the 7-unit code are + +, - + and - -. For the 7-unit signals with the indicator group + -, and having 4 or 5 marks in the 5-unit code, rectifier networks are rendered conductive to provide two or three marks and the remaining two marks are added by pulses selectively derived from trigger devices operated by the 3rd to the 5th elements of the 7-unit code. Rectifier networks operated by the 7-unit code corresponding to the all-spacing signal and to the three service signals operate a trigger device which renders ineffective the circuits for the conversion of the other signals so that no marks, i.e. five spaces, are reproduced, and for the service signals two trigger circuits are selectively operated to produce the combinations + -, - + or + + indicative of the service signals and which through selective circuits, not shown, operate an alarm or initiate some special function.