| 摘要 |
PURPOSE:To decrease the number of analog circuits such as a voltage controlled oscillator, to attain no adjustment of the circuit and to reduce the cost by implementing synchronization control digitally. CONSTITUTION:Whether the phase of a PN code is advanced or delayed is outputted corresponding to 0, 1 level of a digital signal depending whether a correlation output is positive or negative. The driving clock frequency of a PN code generator 7 is controlled by varying the frequency division ratio of a variable frequency divider 11 based on the output. Thus, the synchronization of the PN code at a transmission side and a reception side is attained. On the other hand, a demodulation signal is obtained by passing an input signal to the variable frequency divider through a low pass filter(LPF) 12. Thus, the number of analog circuits such as a voltage controlled oscillator is reduced. |
