Patent ID: 8605830

Claim:
A method comprising: receiving samples {y(n)} of a received signal; computing an estimate of carrier frequency offset based on a frequency location of a largest peak in a magnitude spectrum S(k), wherein the magnitude spectrum S(k) is computed from the samples {y(n)} according to the expression S(k)=|DFT{y(n) 8 }|, wherein y(n) 8 denotes an 8th order non-linearity, wherein DFT denotes the discrete Fourier transform; applying a frequency correction to the samples {y(n)} based on the estimate of the carrier frequency offset in order to obtain samples {v(n)}; computing an estimate of symbol rate of the received signal by searching for a largest peak in a spectrum T(f) over a frequency range, wherein the spectrum T(f) is computed from the samples {v(n)} according to the relation T(f)=DFT{|v(n)| 2 }; computing two candidate values for symbol time offset from a value g(N) given by g ⁡ ( N ) = N 4 ⁢ ⁢ π ⁢ arg [ ( ∑ i ⁢ v 2 ⁡ ( ⅈ ) ⁢ exp ⁡ ( 2 ⁢ ⁢ π ⁢ ⁢ i / N ) ) ⁢ ( ∑ i ⁢ v 2 ⁡ ( ⅈ ) ⁢ exp ⁡ ( - 2 ⁢ ⁢ π ⁢ ⁢ i / N ) ) * ] , wherein N is a first estimate of an oversampling factor, wherein N is determined by the symbol rate estimate and a known value of sampling rate; downsampling the samples {v(n)} based on the symbol rate estimate and a first of the two candidate values for the symbol time offset in order to determine a first symbol sequence; and downsampling the samples {v(n)} based on the symbol rate estimate and a second of the two candidate values for the symbol time offset in order to determine a second symbol sequence; operating on the first and second symbol sequences to determine a type of modulation that was used to generate the received signal; and displaying an indication of the modulation type via a display device.