Industrial Technology Research Institute

Chun-Chian Lu

Chia-Chi Huang

Yung-Liang Huang

A synchronization system and method for obtaining frame, carrier, and sampling synchronization of an input OFDM modulated digital signal having a pseudoperiodic second symbol. The system includes an apparatus for obtaining frame synchronization, and the apparatus includes an envelope detector to detect the first symbol of the input signal, and a differentiator connected to the envelope detector to detect the second symbol. The differentiator includes a first filter having a transfer function H(z)=(1+z.sup.-1) and a second filter having a transfer function H.sub.p (z)=(1-z.sup.-n/2 +z.sup.-n -z.sup.-3n/2), where n equals to a number of samples in the input signal. Synchronization of the carrier frequency offset is obtained by first obtaining the fractional carrier frequency offset, and then obtaining the integral carrier frequency offset through a matched filtering process. Sampling frequency synchronization is obtained through the matched filtering process for determining integral carrier frequency offset.

Synchronization method and system for a digital receiver

A method of frequency estimation is disclosed which uses a Fast Walsh Transform (FWT) in place of a conventional Fast Fourier Transform (FFT) technique. The inventive method is based on a linear relationship between the unknown signal frequency and the sequency of a Walsh function which corresponds to the sample of the FWT with maximum absolute value. The resulting discrete data is smoothed mathematically by a sequency interpolation process, which improves resolution and accuracy. The disclosed FWT method provides greater speed and simpler implementation than the prior FFT technique, since the FWT method follows one simple repetitive data flow pattern (additions only), while the FFT technique follows more complicated butterfly patterns (multiplications and additions).

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Hsinwu Taoyuan, Taiwan

Chun-Chian Lu