| 摘要 |
In a timing component extractor for a digital modulated signal, a frequency converting section 30 receives a complex baseband signal having a symbol rate fs and formed from an I signal and a Q signal, and converts frequency components ±fs/2, which are present in the complex baseband signal as the data changes, to frequency components ±fs/4. The I signal and Q signal of the complex baseband signal are then nonlinearly processed. In other words, multipliers 31, 32 square the I signal and the Q signal, respectively, and an adder 33 adds the respective results of the multipliers 31, 32 . A BPF 34 extracts the frequency components ±fs/2 from the output of the adder 33 , and outputs the extracted frequency components ±fs/2 as a timing signal. Accordingly, processing can be conducted at a sampling frequency which is twice the symbol rate fs. Moreover, timing extraction can be stably conducted without being affected by a carrier frequency offset.
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