Patent GB-770215-A (GB)
Title: Improvements relating to telemetering apparatus and the multiplexing thereof
Inventor: JACOBSON ABRAHAM WALTER
IPC: G08C15/12
Filed: 1954-10-08
Abstract: 770,215. Telemetering. BRISTOL CO. Oct. 8, 1954, No. 29048/54. Class 40 (1). [Also in Group XL (b)] A number of transmitters for signalling the value of a variable by the duration of an electric impulse are connected in turn to a common line or other transmission means by a step-by-step distributer which in each cycle sends a synchronizing impulse to step-by-step apparatus at the receiving station. This apparatus may be a distributer for connecting separate receivers to the transmission means or a device for selecting a characteristic marking element for a recording system in which all the values are shown on the same sheet. Synchronization is effected by delaying the advance of the sending distributer towards the end of each cycle to ensure that the step-by-step receiving apparatus is always ahead at the end of the cycle. The receiving apparatus then stops and is restarted by a synchronizing impulse from the transmitter. First system, Fig. 1. A motor 31 at the transmitter drives a shaft 30 continuously and this gives a step-by-step motion to a distributer 25, 26 which connects transmitters such as 11 . . . 13 to transmission line 19 in turn. At the moment of transition from one instrument to the next, the wipers are disconnected by cams 39, 40. When the last instrument is about to send its reading, wiper 26 is stepped on to contact 27. Relay 42 pulls up to stop the motor, and shortly afterwards, relay 41, which is slow to operate, releases 42 to allow the motor to start again. The delay thus imposed ensures that the step-by-step apparatus at the receiving station will be ahead at the end of the cycle. In due course, the distributer moves on to terminal D and 41 falls back. At the receiving end, a continuously driven shaft 60 similarly controls step-by-step movement of a distributer 55, 56 for connecting elements m of receivers such as 21 . . . 23, resembling that described in Specification 453,571, in turn to front contacts of a line relay 73 after giving them a momentary re-setting impulse at springs 65. Elements m thus respond for a duration determined by the energization of 73. Whereby last of the receivers has been actuated, wipers 55, 56 move on to terminals D<SP>1</SP>, D<SP>11</SP> and relay 72 operates and locks up. Just before the wipers are due to be stepped off these terminals, 71 is operated via springs 67 and stops motor 61. When the sending end distributes cores on to terminal D. the live circuit is completed and 73 pulls up to energize the motor of a time switch 76. In due course this releases 72, 71 and restarts motor 61 and is itself released, and the wipers are stepped to terminals E<SP>1</SP>, E<SP>11</SP>, the delay imposed by 76 being such that the distributers at both ends move to terminals E simultaneously. This arrangement also corrects gross errors of synchronism, the receiving distributer waiting on terminal D until the prolonged line signal when the sending distributer is on terminal D operates the time switch 76 to start motor 61. Any measurement signals received in this position are not long enough to cause 76 to open its contacts and 76 resets each time. Second system, Fig. 3. The transmitting station is the same as in the other system but at the receiving station, the distributer is replaced by a mechanism for rotating the type wheel 120 of a recording system, as described in Specification 690,002. In each position, the type wheel is moved along its shaft from one end to an extent depending on the duration of energization of the line relay 143 and marks a record sheet with a mark characteristic of its angular setting under control of a cam 127. The synchronizing position is indicated by the operation of cam 114 to change over springs 113. Shortly afterwards, cam 112 restores its springs to the position shown and 142 pulls up and locks just before the shaft 101 is again due to be stepped, 112 changes over its contacts again and 141 pulls up and stops the motor 104. When 143 operates in response to the arrival of the sending distributer on terminal D, time-switch 146 is operated and in due course releases 142, 141 to allow the motor to start again.