AFC CIRCUIT, CARRIER RECOVERY CIRCUIT AND RECEIVER

摘要

PROBLEM TO BE SOLVED: To recover a carrier signal synchronously with an input signal while avoiding occurrence of pseudo synchronization or the like even in the case that a synchronizing period of the input signal is short or noise is included in the input signal. SOLUTION: A phase detection circuit 22 being a component of a fine-tuning AFC circuit 14 detects a phase difference of a BPSK signal in I axis, Q axis base band signals while generating the I axis, Q axis base band signals by reception of an antenna 2, guadrature demodulation of a rough adjustment AFC block 4 and frequency conversion of an ODU3. Furthermore, a differentiation circuit differentiates the phase difference to convert the phase difference into a frequency difference and an oscillated frequency of a numerically controlled oscillator NCO circuit 20 is adjusted based on the frequency difference to adjust a rotation angle of a phase rotation circuit thereby nullifying a frequency shift and a phase shift of the I axis, Q axis base band signals.