Patent GB-648754-A (GB)
Title: Telegraph code translating mechanism
IPC: H03M5/00
Filed: 1947-02-21
Abstract: 648,754. Telegraphy. STANDARD TELEPHONES & CABLES, Ltd. Feb. 21, 1947, No. 5131. Convention date, April 24, 1946. [Class 40 (iii)] Multi-element equal-length code combinations in which each element may be either of two kinds are converted into a second equal-length code in which each combination is longer than the first and contains a fixed number of one kind of element by apparatus which comprises means for storing sequentially the elements received in the first code and means for counting one by one the elements of the said one kind in said first code combination while they are being stored. A somewhat similar apparatus for producing the reverse translation also counts the received elements of the said one kind while they are being sequentially received. Translating from five to seven unit code. An incoming start, or equivalent, signal operates relay 1 (Fig. 1) and over contact 13 and distributer 2 operates a release relay 18 to allow the distributer brushes to rotate, and relay 19 to return relay sets 3, 4 and 5 to normal. The received 5-unit combination of marks and spaces is applied sequentially via distributer segments 17 to code-storage relays 24 ... 28 and applied over commoned segments 15 and conductor 16 to a code storage relay 47, which will operate, and lock through relay 66, as soon as one mark is received, the next mark operating relay 48 over operated contact 70, which locks through relay 67. Subsequent marks operate in turn relays 49 ... 51 in the manner of a normal counting-chain. If the received 5-unit combination contains one mark, relay 47 operates and at contact 52 operates an earthing relay 58 which applies earth, over contacts 75 and the particular contact 32 ... 36 corresponding to the received mark, to the corresponding one of five seven-unit contacts 37 ... 41. In order that the seven-unit code shall have three marks, contacts 53 and 54, both normal, apply earth to two extra seven-unit contacts 42, 43 respectively. When the distributer arm reaches segment 46 it operates a transfer relay 45 which transfers the three earths on contacts 37 ... 43 to the seven-unit code relays 6, and at contact 94 starts a seven-unit distributer 90. This distributer sequentially applies an earth over any operated contacts 87 to a transmit relay 91, to transmit the seven-unit code set up on relays 6. If the incoming five-unit combination contains two marks relays 47 and 48 will operate, the latter removing earth from contact 42 so that in addition to the two earths on contacts 37 ... 41 only an additional single earth on contact 43 is set up. If three marks are received, relay 49 also operates and removes the earth on contact 43. If four marks are received, relay 50 also operates, operating relay 69 which at contact 74 releases relay 47 and hence relay 58, and also relay 48. No earths are now applied over contacts 32 ... 36, but instead are applied, over contact 55 and contacts such as 81 ... 83 operated by the four operated marking relays 24 ... 28, to two of the contacts 37...41. A third earth is applied over normal contact 53 to contact 42. When the received five-unit signal contains five marks, all relays 47 ... 51 operate, relay 50 releasing relays 47 and 48 as before. Contact 56 removes earth from the contacts such as 81 ... 83 and applies it instead to contact 41, while contact 57 applies earth to contact 38. The third earth is applied to contact 42 by normal contact 53. The connections between storage contacts 37 ... 43 and storage relays 6 are such that the condition of contacts 42 and 43 are first transmitted followed sequentially by that of contacts 37 ... 41. Thus in the case of five-unit signals containing one, two or three marks for which the contacts 43, 42 and 43, or neither are energized, the seven-unit signals begin with SM, MM or SS respectively, which are followed by the five-unit combination unaltered, while the six five-unit combinations containing four or five marks are converted into arbitrary combinations beginning with mark, space. Translating from seven to five unit code. Seven-unit signals are applied to a receiving distributer 100 (Fig. 2) by a receive relay 99 and hence to the storage relays 101. In the case of those, signals which contain the five-unit combination, the five-unit combination is set up on the last five relays 101 which connect the appropriate five-unit storage relays 113 to an earthing line 105. The circuit through contacts 106 and 107 is broken either at 106, 107 or both and this circuit has no effect oil the storage relays 113. The correct combination is therefore applied by a distributer 114 to a five-unit code output relay 115. If the original five-unit code combination contained four or five marks, the seven-unit signal commences with MS, which is followed by an arbitrary combination of five elements. The signal MS completes the circuit 106, 107 and connects the earthing line 105 to the contacts 110 which are so set by the receive storage relays 101 that in conjunction with contacts 103 they operate the correct ones of the five-unit code relays 113. Earth is connected to the earthing line 105 only when the third mark is received to operate the third relay in a counting chain 102 and so close contact 108. If one, two or four marks are received, one of the other counting relays will earth a line 109 instead to operate an error-indicating device.