Patent GB-680798-A (GB)
Title: Improvements in signal code converters, for example for telegraph systems
Inventor: SNIJDERS ANTONIE
IPC: H04L25/04
Filed: 1948-06-24
Abstract: 680,798. Type-printing telegraphy. STAATSBEDRIJF DER POSTERIJEN TELEGRAFIE EN TELEFONIE. June 24, 1948 [June 30, 1947], No. 17080/48. Class 40 (iii). An arrangement for converting signals comprising m elements, which may be marking or spacing, into a code having a total number n of marking or spacing elements, comprises a number m of two-position switch members with their respective contacts connected to separate equal groups of first resistances and to an equal number of similar groups of second resistances, each switch applying at one contact a marking condition to its group of first resistances and spacing condition to its group of second resistances and vice versa at the other contact, the individual resistances being connected to a number of first conductors equal to the number of signal elements in the first code in such a way that for any setting of the switches a particular electrical condition is applied to one only of the first conductors and each first conductor is connected through a predetermined number of devices responsive to the particular condition to an equal number, but different combination, of second conductors equal in number to u, which are sensed sequentially to produce the corresponding marking and spacing elements in the code of n units. In the schematic arrangement of Fig. 1 the spacing (upper) contacts of five relays I... V connect earth to the groups 1 ... 5, each comprising sixteen resistances, whilst the marking (lower) contacts connect negative battery to the associated group 6 ... 10 of similar resistances. With the armatures reversed appropriate groups of the lower resistances are connected to earth whilst negative battery is applied to the corresponding first groups of resistances. For any setting of the armatures of the relays I ... V earth is applied to one only of 32 first conductors connected to the ends of upper and lower resistances and each first conductor has three connections including individual rectifiers, such as G1, G2, G3, and connected to different combinations of three conductors selected from the group indicated 1 ... 7. The conductors 1 ... 7 are sequentially connected by the brushes of a distributer arrangement VC1 ... VC7 to a valve B1 normally biased to inoperative condition by battery V1 and resistance R174 and rendered conducting when earth is applied, the valve including a load impedance (not shown) in its output circuit. The seven-unit signals corresponding to the thirty-two five-unit signals may be supplemented by three signals derived by individual operation of contacts S1, S2, S3 which replace negative battery by earth on the three lowest first conductors and provide sevenunit signals determined in each case by the connection of the three rectifiers to the appropriate conductors of the group 1 ... 7. The operation of the arrangement for the letter A is illustrated in Fig. 2 in which the conductor 2 is connected to the negative pole of the battery V1 through resistances R18, R163 in series, and to earth through resistances R34, R50, R66 in parallel. Conductor 3 is connected to negative battery, conductor 4 solely to earth and conductors 6, 10, 18 are connected through resistances to negative battery. The conductor 4 with its rectifiers G, 10, 11, 12 is solely operative so that the valve B 1 of Fig. 1 is made conductive solely when the distributer senses the third, fourth and sixth conductors of the group 1 ... 7 to produce the marks and spaces of the corresponding signal in the seven-unit code. The marks and spaces of the five-unit code may be represented by different frequencies or phases of alternating current with the rectifiers G1, G2, ... replaced by frequency or phase discriminators.