| 摘要 |
PURPOSE:To improve the reliability of a receiving circuit by sampling the output signal of a correlating circuit in the center position of a peak of this output signal surely and easily to demodulate a data signal accurately. CONSTITUTION:A base band signal, where a carrier is eliminated from a received signal by a circuit means which is not shown in a figure, is inputted to a correlating circuit 11, and correlations between this base band signal and a PN code are operated, and transfer clocks are counted by a ring counter 16. The second latch circuit 17b latches a synchronizing timing, and the first and the third latch circuits 17a and 17c latch timings before and after the synchronizing timing. The output of the ring counter 16 and outputs of latch circuits are compared by respective comparators. The second and the third sampling circuits sample the output of the correlating circuit 11 by outputs of the first and the third comparing circuits 18a and 18c. The oscillation frequency of a VCO22 is changed in response to the output of a difference circuit 20 which operates the difference between outputs of the second and the third sampling circuits, and the output is given as the transfer clock to the correlating circuit 11, and the transfer clock is allowed to follow up the clock of a spectrum spread signal. |
