Patent ID: 7298772

Claim:
A system for the detection of data packets from a baseband signal where said baseband signal includes data packets which are encoded with symbols which use orthogonal frequency division multiplexing (OFDM), said packets include a short preamble part and a data part, said short preamble part being formed from a plurality of short symbols, each said short symbol comprising a pattern of L said samples, said detection of said data packets comprising: said baseband signal coupled to a first delay line having a delay equal to the time required to receive said L samples, said delay line having an output; a conjugator coupled to said delay line output, said conjugator inverting the sign of imaginary part of said delay line output; a first multiplier having an output, said first multiplier output substantially equal to said baseband signal multiplied by said conjugator output; a first summer having an output equal the sum of L previous said first multiplier output values; a magnitude having an output which has a value equal to the magnitude of the output of said first summer; a second multiplier having a real output, said second multiplier generating said output substantially equal to said baseband signal multiplied by the conjugate of baseband signal; a second summer having an output equal to the to sum of twice said L previous said second multiplier output values; a third multiplier having an output equal to said second summer output multiplied by a first baseline, said output forming a threshold value; said packet detect output asserted when said magnitude output exceeds said threshold value.