| 摘要 |
A receiver comprises a demodulation circuit configured to detect and to recover a received signal comprising one or more frames each with a preamble comprising a plurality of bootstrap Orthogonal Frequency Division Multiplex (OFDM) symbols. A first of the bootstrap symbols has a first time domain structure (C-A-B) configured so that a receiver can synchronise to a useful part of the bootstrap symbols and one or more of the other bootstrap symbols have at least a second time domain structure (B-C-A) and carry signalling data indicating parameters for detecting and recovering the payload data. The receiver uses all of the bootstrap symbols in synchronisation timing for a more accurate of the optimum FFT trigger point 1790 and fine frequency offset 1792. The receiver detects from the bootstrap symbols synchronisation timing and converts, using an inverse Fourier transform, the temporal length of the bootstrap symbols or the payload symbols from the time domain into the frequency domain in accordance with the identified synchronisation timing. The detection utilises a first (auto)correlator 1703 adapted to the first time domain structure (C-A-B) of the first bootstrap symbol and one or more second correlators 1705 adapted to the second time domain structure (B-C-A) of the one or more other bootstrap symbols, one or more delay units 1710, 1712, 1714, 1750, 1752, 1754 configured to delay results produced by the first correlator and the at least one second correlators so that the correlation results are produced contemporaneously for the first and the one or more other bootstrap symbols of the preamble. A combined signal 1744 from the first and second correlators is used to identify the synchronisation timing. |
