Patent GB-781507-A (GB)
Title: Improvements in or relating to telemetering systems for transmitting data to a remote point
IPC: G08C19/14
Filed: 1955-02-04
Abstract: 781,507. Electric selective signalling systems. BENDIX AVIATION CORPORATION. Feb. 4, 1955 [Feb. 26, 1954], No. 3390/55. Class 40(1). A telemetering system, for transmitting data from different sources successively, and successively applying it to different decoders, comprises means at the transmitter for sequentially transmitting over a single communication channel separate signals, each separate signal including simultaneously a quantitative code, representing the data and consisting of a selected combination of a first group of digit waves of different frequencies, and a designation code, for selecting the appropriate decoder at the receiver, and consisting of a selected combination of a second group of digit waves of different frequencies. As shown, a transmitter A is connected by radio or line 10 to a receiver B and is provided with sources f1 ... f4 of different frequencies. The frequencies f 1, and f2, are used to transmit the quantitative codes and with a two-digit binary code four different values can be transmitted. Frequencies f3 and f4 are used for the designation codes providing selection for four read-out devices at the receiver. Four coding switches 15 ... 18, each have an arm 28 which may be manually positioned, or movable in response to, for example, variation in pressure or temperature. The switches 15 ... 18 are successively connected through a rotary switch 19 to the sources f1, f2, and the contacts on the switches 15... 18 are so arranged that at each of the four positions of the arm 28 a different combination is transmitted. A rotary switch 40 is mechanically coupled to the switch 19 and in a similar manner connects sources f3, f4, to any one of four permanently set coding switches 41 ... 44. At the receiver each of the filters 47, 48, 70, 71, passes one of the frequencies f1 ... f4, and blocks the other three, the outputs of the filters 47, 48 being rectified and applied to relays 51, 52, whereby a battery 53 is connected to one or both of the code input terminals 54, 55, of one of the readout devices 56 ... 59. The outputs of filters 70 and 71 are rectified and applied to relays 61 and 63 respectively, whose contacts are connected in a tree circuit whereby the output contacts of relays 51, 52, are connected to different ones of the read-out devices 56 ... 59 depending upon which, if any, of the relays 61 and 63 are energized, and the local source 53 is connected to a control terminal 65 on the selected device. Each read-out-device, Fig. 2, comprises a pair of digit-storing relays 80, 81, an interlock relay 82, and a number change relay 83, the contacts 80a, 81a, and 81b, being arranged in a tree circuit, whereby one or other of lamps 1 ... 4 is energized from a battery 85 according to which, if any, of the relays 80, 81, are energized. Each of the relays 80, 81, also has contacts 80c, 81c, and which are normally closed, contacts 80d, 81d, which are normally open, when the relays are released, which are associated with self-energizing circuits, and with relays 82 and 83. When any read-out device is selected its control terminal 65 is energized to first pull the number change relay 83 and release either or both relays 80, 81, if they were previously operated. Energization of relay 83 energizes relay 82 to release 83 which completes at 83a a holding circuit for each of relays 80, 81, so that if either is operated by energization of code input terminals 54, 55, it holds until that read-out device is again energized.