Patent ID: 7561643

Claim:
An apparatus comprising: a receiver configured to receive a signal transmitted via a communication channel, said received signal comprising digital data and training sequence bits modulated prior to transmission; a sampler configured to sample the received signal and to produce a plurality of received training signal samples (y) corresponding to the training sequence bits of the received signal, the received training signal samples possibly including a DC offset (a dc ); a processor configured to calculate a product of the received training signal samples (y) and a matrix A to provide an extended channel impulse vector (h e ) comprising m channel impulse elements (h) representing the communication channel and a further element representing the DC offset (a dc ), wherein the matrix A comprises a manipulation of an extended reference matrix (X e ) which has m+1 columns where m columns contain reference signal samples representing the training sequence bits and the m+1 column contains a set of rotation elements (e) dependent on the modulation applied to the digital data prior to transmission.