초록 ▼

A discrete multitone modulation transmission system is described in which frame synchronization is monitored at the receiver by correlating frequency domain complex amplitudes of a synchronizing frame with a stored synchronizing pattern. If the correlation result falls below a threshold, indicating

A discrete multitone modulation transmission system is described in which frame synchronization is monitored at the receiver by correlating frequency domain complex amplitudes of a synchronizing frame with a stored synchronizing pattern. If the correlation result falls below a threshold, indicating a loss of frame synchronization, a plurality of correlations are performed, in each case using the stored complex amplitudes of the synchronizing frame multiplied by a respective complex value representing a respective complex derotation corresponding to a respective possible time shift of the synchronizing frame. The best correlation result, if it exceeds another threshold, indicates a time shift for restoring frame synchronization, this being possible before the next synchronizing frame is received.

대표청구항 ▼

A method of monitoring frame synchronization in a multicarrier modulation transmission system in which a synchronizing frame containing at least a synchronizing pattern is transmitted, said method comprising: (a) receiving values of the synchronizing frame, the values of the synchronizing frame bein

A method of monitoring frame synchronization in a multicarrier modulation transmission system in which a synchronizing frame containing at least a synchronizing pattern is transmitted, said method comprising: (a) receiving values of the synchronizing frame, the values of the synchronizing frame being complex amplitudes; (b) comparing the values of the synchronizing frame with corresponding stored values of the synchronizing pattern to produce a comparison result; (c) comparing the comparison result with at least one threshold value to provide an indication of existence or loss of frame synchronization; (d) determining an adjustment amount to restore frame synchronization when said comparing (c) indicates that the frame synchronization has been lost, said determining (d) including the operations of (d1) derotating of the complex amplitudes of the synchronizing frame in accordance with respective time shifts to produce a plurality of derotated complex amplitudes, and (d2) correlating the stored values of the synchronizing pattern with respective ones of the derotated complex amplitudes of the synchronizing frame to produce a plurality of correlation results; and (e) adjusting a frame boundary in accordance with the adjustment mount to restore frame synchronization.