Patent GB-946539-A (GB)
Title: Means for indicating the passage of a rail vehicle past a given point on a railway system
Inventor: RAYNER CHRISTOPHER STEPHEN
IPC: B61L3/04
Filed: 1959-01-27
Abstract: 946,539. Vehicle identification. JOSEPH LUCAS (INDUSTRIES) Ltd. Jan. 18, 1960 [Jan. 27, 1959], No. 2868/59. Heading B7N. [Also in Division G4] In an arrangement for reading a number in binary code marked by sound reflecting elements on a moving railway vehicle, the trackside equipment includes a recognition head 10, Fig. 2, with centrally disposed ultrasonic transmitter 11 and four ultrasonic receivers 12-15 disposed to opposite sides of and above and below the transmitter and the reflecting unit, Fig. 1, mounted on an unsprung part of the vehicle, includes a series of inclined equispaced reflectors 17 which reflect energy to the upper receiver 14, a series of inclined reflectors 18, which are arranged by their presence or absence opposite reflectors 17 to mark the number peculiar to the vehicle in binary code, which reflect energy to receiver 15 and end reflectors 20 which are oppositely inclined and reflect energy to receivers 12 and 13 as the unit moves into and out of the transmitted ultrasonic beam. Assuming the vehicle moves to the left, receiver 12 is initially energized by a reflected pulse of ultrasonic energy. The resulting R.F. signal is amplified 21 and that part of the signal exceeding the bias of an amplitude discriminator 22 triggers circuit 23 to produce a constant amplitude signal during the period the discriminator bias is exceeded. This signal is differentiated 24 to produce a narrow output pulse which passes via inhibiting circuit 25 and actuates inhibiting circuit 27 to prevent the passage of a pulse generated in receiver 13 as the reflector unit passes out of the beam, produces a response in a direction store 26 indicating the direction of travel of the vehicle and triggers multivibrator 28. The multivibrator signal pulse is amplified 29 and writes the identification number of the recognition head in a shift register 30, clears an input shift register 31 writes " 1 " in element 31a of this register, which acts as an alerting signal for subsequent operation and triggers a multivibrator 32 which produces a pulse to open gate 33. The equispaced clock signals produced in receiver 14 by reflecting elements 17 now pass via gate 33, circuits 34-37 (similar to circuits 21-24) and trigger monostable multivibrator 38. The multivibrator pulses gate 39 the code signals produced in receiver 15 by code marking elements 18 and also operate via amplifier 40 the shift circuit of register 31 whereby the code pulses are written into the register via amplifier 44. When the alerting signal (initially in element 31a) reaches element 31x it produces a signal which passes via gate 45 to amplifier 46. The amplifier output triggers multivibrator 32 which closes gate 33, re-writes a " 1 " in element 31x and triggers multivibrator 48. This produces a pulse which writes a " 0 " or " 1 " in register 31 depending on the position of direction store 26 and opens gate 50 via which the output of " pass to store " generator 51 is applied to the register shift circuit and transfers the contents of register 31 to temporary store register 53. When the alerting signal " 1 " reaches element 53x it produces a signal which is passed to amplifier 54. The amplifier output pulse closes gate 50 and prevents further shift of the code and opens gate 56 to allow a " signal ready " signal to be passed to a local computer. The return signal from the computer is detected 58, differentiated 59 and via multivibrator 55 opens gate 60. It also triggers a read out pulse generator 61 which shifts the contents of registers 30 (identification number) and 53 (coded number) via gate 60 into transmitter 62 which passes the information to the local computer.