| 摘要 |
PURPOSE: To allow the system to receive an analog signal to be modulated and convert the signal frequency into a lower coherent frequency, so as to convert the analog signal into a filtered digital signal without a phase error. CONSTITUTION: In an embodiment, the conversion system 10 has an analog signal multiplier 16, an A/D converter 18, an oscillator 12 and a frequency divider 14. The signal multiplier 16 converts a frequency of the analog signal, and the A/D converter 18 converts the analog signal into a digital signal. The frequency divider 14 receives a clock signal from the oscillator 12 and divides the frequency of the clock signal. Since the same clock signal is used for frequency conversion and A/D conversion, no phase error is included in the output digital signal. Furthermore, the frequency divider 14 forcibly sets an integer ratio to the frequency of the analog signal and the digital signal, so as to be demodulated later.
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