Patent GB-826384-A (GB)
Title: Improved selecting, routing and receiving system and apparatus
IPC: H04Q9/16
Filed: 1956-04-23
Abstract: 826,384. Electric selective signalling. SHAND & JURS CO. April 23, 1956 [May 6, 1955], No. 12413/56. Class 40 (1). A telemetering system provides indications at a reading station of information in the form of two or more series of pulses from a selected one of a plurality of transmitting stations, and comprises means at the reading station for sending a start pulse to initiate the operation of the selected transmitting station, routing means at the reading station for routing each series of pulses to appropriate indicating means, the routing means including timing means for advancing the routing means if no pulses are received during a time interval allotted to the reception of indication pulses, and means for resetting the system upon completion of the indicating operation. A warning is operated if an incorrect selection of a transmitting station is made. General arrangement of a typical system for reading liquid levels &c. at remotely located tanks. A reading station 10, Fig. 1, comprising selecting and receiving apparatus 17, routing apparatus 18, and indicating devices 16, is connected to remote selectors 11 which are connected to one or more further remote selectors 11. Each remote selector is connected to transmitters 12 at tanks 13, and the apparatus 17 is connected direct to local transmitters 12 and tanks 13. The connections may be by wire or radio link. At the reading station 10 the apparatus 17 and 18 includes means for transmitting one or more groups of selecting pulses, the number of pulses in each group being determined by the tank station and remote selector to be selected, and means for sending a start pulse to actuate the transmitter 12 after the transmission of the selecting pulses. The transmitter 12 then sends one or more groups of confirming code pulses followed by other information pulses, e.g. foot and inch pulses giving the level of liquid in the tank. The confirming code pulses and information pulses are transmitted to apparatus 18 through the connection previously established the confirming code pulses being routed to apparatus 17 which provides an indication as to whether or not the correct tank station has been selected, and the information pulses being routed to indicating devices 16. The complete system is homed after each reading operation. Arrangement providing remote selection through a single remote selector 11. Figs. 3 and 4 show one embodiment of the routing apparatus 18 and selecting and receiving apparatus 17 respectively, terminal T11 being connected to the remote selecting apparatus 11 of the type described in Specification 826,383 which in turn is connected to a plurality of transmitters 12. It is assumed that the wiper of the manually operated switch S2 is positioned on terminal 1 to take the reading of the first transmitter 12. Terminals 1 to 20 of S2 are connected to terminals 1 to 20 of bank 2 of S3, and to corresponding terminals of S4. When the remote apparatus 11 is on the home position earth is maintained continuously on T11 and with the apparatus shown in Figs. 3 and 4 also in the home position relay L is energized and ready light 29 glows. When lamp 29 glows the start button 27 may be pressed, whereby relay K is energized and establishes a holding circuit to permit release of the start button, and puts a negative potential on terminal Tl to operate relay A. Operation of A energizes motor 41 to operate pulsing contacts S5 and when contacts 3, 4 of S5 are closed relay B picks up and establishes a holding circuit, and via contacts 1, 2 of S5 pulses are sent over terminal Til to the remote apparatus 11. When B picks up, the step coil D for switch S3 is energized via contacts 1, 2 of S5, each de-energization of D advancing 53 one step. In this way 83 is advanced one step for each pulse sent out through Tll 1 until the wiper of bank 2, 83, finds the terminal earthed by the selected terminal on S2, in this example, terminal 1, and thereby shunts relay B which is thus de-energized after the termination of the first pulse. If, for example, terminal 18 had been selected on S2, S3 would have been advanced to terminal 18 and eighteen pulses would have been transmitted. When relay B releases, S3 steps rapidly to terminal 51. In the event of a power failure between operation of start button 27 and this stepping operation, relay A is de-energized and S3 will home on terminal 52. When S3 steps to terminal 51 relay C is energized via contacts 2, 3 of relay A, establishes a holding circuit, and releases A to advance S3 to 52. When C picks up slow-tooperate relay T is energized to control the transmission of a start pulse via Tll to the remote selecting apparatus, and step coil N is energized to step the wiper of switch 81 from terminal 1 to 2. Energization of T also starts the motors of time delay devices TD1, which is set to operate its contacts during the time when the " foot " pulses normally would be received, and TD2, which operates when the " inch " pulses normally would be received. The apparatus is now in condition to receive confirming code pulses from the selected transmitter 12 to check that a correct selection has been made. The transmitter periodically earths the line connecting it to apparatus 11 and terminal T1 1 in the manner described in Specification 741,622 causing operation of relay L. The rectifier 30 and resistor R2 produce a delay in the drop out time of L and R2 may be adjusted to correct for line distortion. Operation of L causes a pulse to be sent via terminal 2 of bank 1, S1, to T9 to energize step coil E to advance S4 from terminal 0 to terminal 1, and operates slow-release relay P. The release time of P is such that it remains operated between pulses from transmitter 12. Each time the earth on lines 21, 23 is removed by transmitter 12, L releases, and each time L picks up it causes S4 to advance another step. In the present case the first transmitter was selected by 52 and only one confirming pulse is received by S4 to advance it to terminal 1 and earth one side of relay F which is provided to confirm a correct selection. After the confirming code pulse has been sent a predetermined interval elapses before additional information is sent by 12 during which P releases and causes step coil N to advance Sl to terminal 3 to earth the other side of F and prevent its operation. In the event of an incorrect selection, and F has not been earthed by 54, F will operate, or if for any reason S does not advance to 3, after a time delay TD1 closes contacts 2, 3 to operate F and light lamp 45 to indicate faulty operation and release relay K to home the apparatus. F is released by pressing button 46 and the same reading operation may be re-started by pressing button 27. When the selection is correct, transmitter 12 sends pulses indicating feet by periodically earthing line 23 to periodically operate L which sends corresponding pulses over terminal 3, bank 1, S1, to indicating step coil 31. Operation of L causes P to pick up, and after a predetermined time P releases to allow energization of step coil N via contacts 2, <SP>,</SP>3, of delay device TD1. When no " foot " pulses are received TD1 ensures that step coil N is energized although P is not energized. Energization of N advances 81 from 3 to 4 and after a predetermined interval the transmitter sends pulses indicating inches. L follows these pulses and causes an equal number of pulses to be sent via S to indicator step coil 32. When the transmission is completed, P releases to energize step coil N and advance S from 4 to 5. In the event of no " inch " pulses TD2 operates in a similar manner to TD1. After Sl has been advanced to terminal 5 the apparatus may be housed by operating button 28 to release K, followed by T and C, and energize reset coil M and indicator reset coils 33, 34. Release of C energizes step coil E to home S4. The remote selecting apparatus is provided with means for automatically homing after a predetermined time. Modifications. Apparatus for selecting only local transmitters, Fig. 2 (not shown). In this case the apparatus shown in Fig. 4 is not required, the transmitters being selected by a rotary selector switch to which they are directly connected, and therefore it is not necessary for the transmitters to send confirming pulses. Similar apparatus may be used for connection to automatic printing apparatus, Fig. 8 (not shown). In this case the selecting switch is dispensed with, the transmitters being connected to a common line and each arranged automatically, e.g. by clockwork mechanism, to transmit at predetermined times. In a modification of Fig. 4, additional means are provided for the direct selection of transmitters located near the reading station 10. Arrangement providing remote selection through remote selecting apparatuses 11 connected in cascade, and providing facilities for selecting local transmitters, Figs. 6 and 7. Means are provided for sending two series of selecting pulses and receiving two separate series of confirming code pulses, together with warning means to indicate when the incorrect transmitter has been selected by remote selecting apparatus 11. Terminals 1 to 20 of bank 2 of S10 are connected to the local transmitters and terminals 1 to 10 of bank 3 of S9 are interconnected and connected to the remote selection apparatus 11. Assuming that switches S9 and S10 are placed in the positions shown, start button 27 is pressed and S3 is stepped until the wiper of bank 2, S3, finds the marked contact on bank 1, S9, one pulse being sent over line 21 by impulse switch 55 for each step of S3. This operation is similar to that described for Fig. 4. When the wiper of S3 reaches the earthed terminal relay B is released to terminate the first series of pulses on line 21, and contacts 3, 4 of relay B are closed to step switch S3 rapidly until it reaches terminal 21 and step coil D is de-energized, since relay A is energiz