Apparatus and method for carrier recovery of base-band receiver in high order QAM systems

摘要

An apparatus and a method for recovering a carrier in a baseband receiver of a QAM(Quadrature Amplitude Modulation) system of a high order are provided to maintain a capturing time uniformly although a carrier frequency offset increases by operating a carrier recovering device having a wide frequency recovering range and a fast capturing time. An apparatus for recovering a carrier in a baseband receiver of a QAM(Quadrature Amplitude Modulation) system of a high order includes a phase detection unit(250), a polarity detection unit(230), a frequency detection unit(240), and a fixed signal detection unit(260). The phase detection unit detects a phase offset of a baseband signal of which a phase is changed. The base band signal is received to a carrier recovering device. The polarity detection unit detects a polarity of a selected symbol used for recovering the carrier. The polarity detection unit detects a phase offset of the selected symbol based on the polarity. The frequency detection unit detects the frequency offset based on an output of the polarity detection unit. The fixed signal detection unit detects whether the phase offset and the frequency offset of the carrier are removed below a predetermined reference value. The fixed signal detection unit switches one of the output of the phase detection unit, the output of the polarity detection unit, and the output of the frequency detection unit to be used for capturing the carrier.