| 摘要 |
PURPOSE:To realize a unique word detection circuit which is stably operated even when a frequency of a receiver has an error against to a frequency of a reception signal. CONSTITUTION:A local oscillator 1 almost tuned to a reception signal implements quasi-synchronization detection to convert the signal into a complex specified band signal, and A/D converters 6,7 sample and implement A/D conversion to the signal. The sampled value is inputted to shift registers 8,9 for N- sample length. On the other hand, a unique word pattern generator 11 generates a known unique word pattern in a complex number form and the pattern is subject to complex multiplication with each tap signal from the shift registers at complex multipliers 101-10n. A filter group 12 receiving N sets of parallel outputs from the complex multipliers implements the FFT arithmetic operation then the absolute values of the N-sets of the outputs subject to FFT arithmetic operation are compared and it is discriminated that the unique work is in existence in the presence of an output of the absolute value larger than a mean value by a specified threshold value and a frequency error of the reception signal is simultaneously detected from its output terminal in this unique word detection circuit. |
