Code synchronization in a receiving device for spread spectrum communication systems

摘要

A receiving device is provided with a DLL circuit of a reduced scale. An inverse spreading processing to ensure the synchronism with a received signal and a processing to inversely spread original data in the received signal are performed by a time-sharing operation using one inverse spreading circuit (17) and one integrator (18). During a period in which synchronous data for detecting a slot duration included in the received signal is received, the synchronous data is alternately inversely spread by an early code and a late code and sample-hold circuits (14,15) alternately sample and hold the integrated output. Further, based on the difference (error signal) between sample-hold signals, the early code, the late code and a reference code outputted from a code sequence generator (9) are synchronized with the received signal. Then, the inverse spreading circuit and an integrator inversely spread the original data in the received signal based on the synchronized reference code and a detection output is generated by integrating the inverse spreading output.