Rueckmeldegeraet zur Identifizierung von Objekten

摘要

1,228,182. Transponders; inductive signalling. M. S. KEELER. 2 May, 1968 [5 May, 1967], No. 20825/68. Headings H4L and H4U. In an interrogator-responder system, e.g. for identifying vehicles, the interrogator transmits an R.F. signal which is rectified at the responder, Fig. 1 (not shown), to provide an operating potential for the responder on lead A1, Fig. 2. The signal may be transmitted and received by conventional aerials or inductive coupling may be used. Operating voltage on lead A1 is supplied via a normally conductive transistor Q1 and Zener diode 32 to the base of a "start" transistor Q2, the emitter of Q2, being connected to earth through an RC timing circuit 34, 36. When the operating voltage reaches a predetermined value the transistor Q2 conducts and switches on the first silicon control switch 42 in a chain of such switches 42 to 54. The outputs of switches 42 and 54 are connected via diodes to both leads 56, 58 to define the start and end of the code signal and the remaining outputs are connected to one or the other lead in accordance with the coding required. A switch 86 converts the chain into a ring circuit so that the code transmission may be repeated. When SCS 42 conducts, leads 56, 58 and 66 are energized, the signal on leads 56, 58, through varactor diodes 142, 138 tone modulating an R.F. carrier generated by transistor oscillator Q7 and transmitted via aerial 116. The signal on lead 66 triggers a unijunction device 94 when the charge on capacitor 104 reaches a predetermined value, adjustable by resistor 100, so that a transistor Q3 conducts and cuts off transistor Q1 to interrupt briefly the power supply and cut off SCS 42. When capacitor 104 is being charged and before unijunction 94 is triggered, a voltage is applied to switch on a transistor Q4 followed by transistor Q5 which in turn switches on transistor Q6 in the power supply of the R.F. oscillator 26. The transmitter 26 will remain on until the unijunction 94 is triggered and when SCS 42 is cut off the charge on capacitor 68 causes SCS 44 to conduct and the cycle is repeated but this time only one of the varactors 138, 142 is operative.