Patent ID: 7076002

Claim:
An apparatus for symbol boundary synchronization in a multi-tone modem with a plurality of components forming a transmit path and a receive path: and the receive path components of the multi-tone modem comprising: a window synchronizer to obtain windowed portions of a received datastream with symbols each expressed with a corresponding set of tones in a time domain and with the windowed portions obtained in a training phase exhibiting varying degrees of misalignment with corresponding symbol boundaries and with the window synchronizer responsive to an alignment signal to obtain succeeding windowed portions of the incoming datastream aligned with the corresponding symbol boundaries therein; a converter coupled to the window synchronizer to convert the set of tones from each windowed portion from the time domain to a frequency domain; and a symbol boundary component coupled to the converter to evaluate a phasor angle characteristic of selected tones from each windowed portion converted by the converter and to convert the phasor angle characteristic of the selected tones from a selected one of the windowed portions to the alignment signal to align the window synchronizer with the symbol boundaries in the received datastream and the symbol boundary component including: a calculator for selecting at least one set of adjacent pilot tones within each successive windowed portion and for determining for each adjacent pair of tones in the at least one set a corresponding phasor resulting from multiplying a one tone of each adjacent pair by a complex conjugate of an other; a peak detector for detecting from among the phasors of successive windowed portions from the calculator, a peak phasor which exhibits a peak magnitude; and a converter for converting the phasor angle of the peak phasor detected in the peak detector to the alignment signal with a tone offset required to align the windowed portion obtained by the window synchronizer with the corresponding symbol boundaries.