| 摘要 |
PURPOSE:To realize AFC in the transmitter.receiver of a TDD system. CONSTITUTION:At the time of connection, a signal Sr modulated by a control signal with a non-modulating part is transmitted and received. A signal line to supply the signal S39 from the modulation circuit 12 of a transmission circuit 10 to a reception circuit 20, a frequency discrimination circuit 72, and a storage circuit 31 are provided. The signal S39 from the modulation circuit 12 of the transmission circuit 10 is supplied to the reception circuit 20 through the above- mentioned signal line, and voltage V72 outputted from the frequency discrimination circuit 72 is stored in the storage circuit 31 as reference voltage Vrf. The AFC is executed by controlling the frequencies of a carrier signal Si to be supplied to the modulation circuit 12 and a local oscillation signal Sj to be supplied to the reception circuit 20 so that the voltage outputted from the frequency discrimination circuit 72 during the period of the non-modulating part 81 coincides with the stored reference voltage Vrf.
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