| 摘要 |
PURPOSE:To take quick carrier synchronization even from a reception burst having a large frequency detuning at a low transmission speed. CONSTITUTION:A time division PLL loop(TDPLL) is formed by a complex multiplier 1, a phase difference detector 2, a low pass filter 3, an adder 4 and a digital VCO 5. A DC level representing a recovered carrier component of a reception burst is obtained by a square circuit 9 from a base band signal being an output of the complex multiplier. The TDPLL acts like a PLL having a different frequency lock range from time division at the unreception of a burst and at a first half of the carrier recovery part in the reception burst. The TDPLL acts like a PLL in a frequency range in which the DC level obtained during time division is maximized after the end of time division operation. |
