A variation on the quadrature amplitude modulation (QAM) signal modulation scheme. 256-QAM yields 256 possible signal combinations, with each symbol representing eight bits (2 8 = 256). The yield of this complex modulation scheme is that the transmission rate is eight times the signaling rate. In the United States, 256-QAM is used in digital CATV applications. See also amplitude, bit, modulation, QAM, signal, signaling rate, symbol, and transmission rate.