Patent GB-1270233-A (GB)
Title: Utility meter remote automatic reading system
IPC: H02J13/00
Filed: 1970-01-16
Abstract: 1,270,233. Counters; electric selective signalling. NORTH AMERICAN RESEARCH CORP. 16 Jan., 1970 [14 March, 1969], No. 2297/70. Headings G4A and G4H. In a system for reading remote utility meters from a central station, the address code of a meter to be read is transmitted to all meterstations of the system where it is compared with the meter address code held in a memory, agreement of the two codes causing the meter reading held in another memory to be transmitted to the central station. Transmission may be by way of power lines or by radio or acoustic channels or a combination of these, with the central station either permanent or mobile. The central station transmits a binary address code as bursts of one of two frequencies representing a 1 and 0. A start signal precedes the address code and is either a burst of a third frequency or simultaneous bursts of the other two. Each meter-station is activated by the start signal and the arriving address code is compared bit by bit with the address code of the meter freshly transferred into a shift register from the meter address code memory. Non-correspondence with any of the bits causes the meter-station to close down. The selected station will find complete correspondence and on so doing transfers the binary or binary decimal meter reading in parallel to a shift register, from which it is serially shifted out and transmitted using the two frequencies used for the address code. The stations are initially clocked by the received address code bits and any station not receiving all address code bits, due say to faulty transmission, is timed out. Several arrangements are described for reading and storing the reading of the meter. If the meter produces a pulse(s) per unit of utility, for example photo-electrically, inductively or capacitively (Figs 11, 12, 13, not shown), the pulses are stored in either a counter or a non-accumulating store whose contents have to be shifted out in parallel to a register for a one to be added to the reading and then shifted back. Alternatively a meter having decimal dials may be read photo-electrically (Figs. 14, 15A, not shown) and the decimal reading transformed into binary coded decimal and parallel shifted into a register for serial transmission. In reading the dials carry transmission errors are avoided by logic circuits. If the above counter and non- accumulating store are being updated when an interrogation of the meter starts, the interrogation takes priority and the updating is not resumed. Two stages of a counter for the meter reading are shown in Fig. 8. A read, write or update pulse at OR gate 371 fires one shot multivibrator 371 which subsequently fires one shot multivibrator 372. If core 317 held a 0 the pulse from 371 flips the core to a 1 state and the signal induced on winding 369 inhibits flip-flop 374 so nullifying the pulse from 372 on winding 319. Another pulse now arriving at OR gate 375 drives the core into saturation with the pulse from 371, resulting in no signal on winding 369 thereby allowing the flip-flop 374 to be set and allowing the pulse from 372 to reset the core to zero. A pulse then appears on read winding 321 for exit at read gate 377 and for setting the next stage.