The extended Kalman filtering algorithm applied for carrier synchronization and the implementation are studied in this paper. The major advantage of the Kalman-based scheme over the conventional phase-locked loop (PLL) is the self-adaptation of loop bandwidth for better compromising the tradeoff between fast acquisition and small phase tracking variation. We have developed the idea to a practical application example of the cable modem downstream receiver. From simulations and implementation results, it is shown that the Kalman-based approach can achieve much shorter acquisition time than the conventional PLL structure. A 64-QAM receiver with a two-state Kalman filtering carrier recovery is designed and verified on Xilinx Spartan-3 FPGA.