Modulation order

The modulation order of a digital communication scheme is determined by the number of the different symbols that can be transmitted using it. The modulation order of a digital communication scheme is determined by the number of the different symbols that can be transmitted using it. Modulation order can only be defined for digital modulations. The simplest forms of digital modulation are of second order because they can transmit only two symbols (usually denoted as '0' and '1' or as '-1' and '1'). They are called binary shift keying (BSK). Modulations which have an order of 4 and above usually are termed as higher-order modulations. Examples of these are quadrature phase shift keying (QPSK) and its generalisation as m-ary quadrature amplitude modulation (m-QAM).