| 摘要 |
PURPOSE:To prevent malfunction of a receiver side of a demodulation main signal at the time of out of synchronism. CONSTITUTION:A phase modulation signal (a) is applied to a phase detector 1 and subjected to synchronization detection by a reproduced carrier (f) being an output signal of a VCO 4 and a base band signal (b) is outputted. The base band signal (b) is inputted to an identification device 2 and an APC 3, and a demodulation main signal (c) is outputted from the identification device 2. Moreover, the APC 3 outputs an APC signal (e) to control the VCO 4. The APC signal (e) is also fed to a carrier asynchronous detection circuit 5, and when the carrier asynchronous detection circuit 5 detects it that a reproduced reference carrier (f) is in the synchronization state, a control signal (g) controls a switch circuit 6 to output a demodulation main signal (c) outputted from the identification device 2 as a demodulation main signal (d). However, when the reproduced carrier is asynchronous, the carrier asynchronous detection circuit 5 uses the control signal (g) of a preset logic level to control the switch circuit 6 thereby preventing a random signal from being outputted from the identification device 2. |
