| 摘要 |
PURPOSE:To receive a data signal satisfactorily by repeating the phase change of a spread code by using spread codes with code speed different by little so that a noise level included in a demodulation signal can be set less than a prescribed value. CONSTITUTION:The clock pulse frequency of each clock generation circuit 13 is set so that the code speed of an M series code on a transmission side can be set at 2MHz and the code speed on a reception side can be set at the one higher by 5 to 10Hz than that. A counter 142 starts a count operation when no synchronism between the M series codes on the transmission and reception sides is taken, and the phase of the M series code on the reception side is delayed sequentially by every 1/4 bit, and such operation is continued until the voltage of a noise level signal goes less than a constant voltage VA. When phase delay is stopped, the voltage of the noise level signal goes over the constant voltage VA again. Then, a phase delay operation is started again. Thus, it is possible to always maintain the synchronism between both M series codes, and to perform data communication satisfactorily. |
