| 摘要 |
PURPOSE:To make it secure to discriminate a characteristic code by eliminating the influence of fluctuation of the frequency of a discriminator which uses a microwave, by reading a memory with a clock signal which synchronizes with an interrogation signal and by generating an responder signal by two frequency dividers. CONSTITUTION:Interrogator 11 generates microwave carrier signal fc, and clock signal fs to be used by responder 12 and the both are mixed and sent out. A radio wave arriving at responder 12 is partially rectified via demodulator 20 to be used as a DC power source. The remainder is supplied to frequency dividers 22 and 23 to generate signals f1 and f2 while clock signal fs is generated by frequency divider 24. Clock signal fs is supplied to read only memory 26 via counter 25. In memory 26, the signal characteristic to responder 12 is stored and according to the memory contents, switches 27 and 28 operate by turns to send out the characteristic answer signal, FSK-modulated by output signal f1 or f2, from antenna 30. This signal is supplied to signal processing part 35 of interrogator 11 to discriminate the code characteristic to the responder. |
