Patent ID: 8295402

Claim:
An apparatus, comprising: an intermediate variables calculator having a symbol input and an output, wherein the symbol input is adapted to accept a plurality of DQPSK symbols that are each characterized by a real component and an imaginary component, and wherein said intermediate variables calculator is adapted to output three intermediate variables that are each based on one or more second order products of the real components and the imaginary components of the DQPSK symbols, wherein each of the second order products is a second order product of the real component of a DQPSK symbol and the imaginary component of the same symbol; a channel amplitude estimator coupled to the intermediate variables calculator and adapted to output an estimate of the channel amplitude that is responsive to the intermediate variables; a channel phase estimator coupled to the intermediate variables calculator and adapted to output an estimate of the channel phase that is responsive to the intermediate variables; and a channel noise variance estimator coupled to the intermediate variables calculator and adapted to output an estimate of the channel noise variance that is responsive to the three intermediate variables.