| 摘要 |
PURPOSE:To provide the small and stable demodulation device of a pi/4 QPSK modulation wave, in which adjustment is simplified by digitalizing whole circuits. CONSTITUTION:The demodulation device by the delay detection system of the pi/4 QPSK modulation wave multiplies a reception signal by a reception signal delayed in a delay means by one symbol time by a multiplier, detects an I base signal, fetches the signal through a sampling means, multiplies the reception signal by a signal obtained by changing the phase of the reception signal delayed in the delay means by one symbol time by 90 degrees in the multiplier, detects a Q base band signal and fetches the signal through the sampling means. Shift registers 1 and 2 operating by a clock signal S2 are used as the method of the delay means and the phase shift means, the D flip flops 5 and 8 as the sampling means and the whole circuits are digitalized. |
