Synchronizing signal extraction circuit for tdd system and method of the signal extraction

The present invention relates to a technique applied to a mobile communication, the time-division half-duplex transmission (TDD) by receiving a radio wave, etc. repeaters using the system extracts a synchronization signal required to retransmit the signal from the received signal, the retransmission signal and the synchronization required to (Synchronize) inde circuit, to a sync extraction circuit for generating a phase locked signal, such as the input signal output via this output. The inventors sync extraction circuit, for detecting a synchronizing signal in a band-pass filter 10, the band-pass filter that passes only signals of the desired frequency from the RF signals received signal the signal detector 20, from the signal detector digital filter 30, after restoring the sync signal the digital phase-locked loop (40, DPPLL) for fixing the output phase of the oscillator, which oscillator 50 generates an electrical oscillation in pulse form for removing the noise of the detected signal and an output section 60 for outputting a synchronizing signal using the output of the oscillator. The present invention it is possible to extract the synchronization signal from the radio wave signal using a TDD scheme large and the application, as the circuit configuration is relatively simple structure, to sayom the DPPLL high reliability, while the product of the components circuit less compact the manufacturing cost can be inexpensive, and minimize other problems such as heat generation by reduction of the power consumption due to reduced number of parts. Sync extraction, signal detector, a digital filter, TDD, digital phase-locked loop, the oscillator