Design of carrier recovery algorithm for high-order QAM with large frequency acquisition range

We propose a polarity decision carrier recovery algorithm that is useful for carrier acquisition in high order-QAM (quadrature amplitude modulation). The PD (phase detector) output and its variance characteristics are mathematically derived and the simulation results are presented. We design a carrier recovery loop with this polarity decision PD and ATC (automatic transfer-mode controller), which is proposed to detect a proper time for mode change and to yield fine phase tracking error in the steady state. While the conventional DD (decision directed) algorithm can only acquire frequency offsets of less than ±10 kHz, the proposed carrier recovery algorithm can acquire up to ±200 kHz without AFC (automatic frequency control). We show the RMS (root mean square) phase error performance using the proposed carrier recovery PLL (phase locked loop)