Patent ID: 6904104

Claim:
An apparatus for demodulating a data signal previously modulated using linear modulation, comprising: a receiver section for receiving the linear modulated data signal and producing an in-phase signal and a quadrature phase signal from the linear modulated data signal; a conversion section for transforming by sampling and quantizing the in-phase signal into an in-phase sample stream and the quadrature phase signal into a quadrature sample stream, respectively, the in-phase sample stream and the quadrature sample stream being over-sampled at a rate of N times a symbol rate of the data signal; a decimation section for fitering the in-phase sample stream and the quadrature sample stream to produce a reduced in-phase sample stream and a reduced quadrature sample stream at a rate of M times the symbol rate, wherein M is less than or equal to N; an in-phase buffer pair for receiving the reduced in-phase sample stream, each in-phase buffer holding L 1 samples of the reduced in-phase sample stream; a quadrature buffer pair for receiving the reduced quadrature sample stream, each quadrature buffer holding L 2 samples of the reduced quadrature sample stream; a decision component for calculating, for each in-phase buffer and each quadrature buffer, the magnitude of a combination of the L 1 samples of the in-phase buffer and the L 2 samples of the quadrature buffer and for selecting an in-phase buffer of the in-phase buffer pair and a quadrature buffer of the quadrature buffer pair, respectively; wherein, the selected in-phase buffer and the selected quadrature buffer are associated with the combination of samples having a largest magnitude; wherein, responsive to the in-phase buffer selection, an in-phase sample is output; and wherein, responsive to the quadrature buffer selection, a quadrature sample is output.