前言
　在數(shù)據(jù)采集系統(tǒng)中,，模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換" title="模數(shù)轉(zhuǎn)換">模數(shù)轉(zhuǎn)換器是其中至關重要的環(huán)節(jié)，模數(shù)轉(zhuǎn)換器的精度以及系統(tǒng)的成本直接影響到系統(tǒng)的實用性,，因此,，如何提高模數(shù)轉(zhuǎn)換器的精度和降低系統(tǒng)的成本是衡量系統(tǒng)是否具有實際應用價值的標準。
　一般來說,，想提高模數(shù)轉(zhuǎn)換器的精度,，勢必會引起成本的增加，這就要求我們按照具體的精度要求合理的設計模數(shù)轉(zhuǎn)換器,，來達到具體的要求和降低系統(tǒng)的成本,。在精度要求不是很高的場合，我們經(jīng)常利用嵌入微控制器片內(nèi)的A/D轉(zhuǎn)換器來實現(xiàn)模數(shù)轉(zhuǎn)換,，以此來降低系統(tǒng)的成本,，但由此又產(chǎn)生了另外的問題，嵌入式模數(shù)轉(zhuǎn)換器是否具有所要求的精度,，若超出測量范圍如何與測量電路進行接口,，以及如何減小微控制器的電磁干擾提高嵌入式模數(shù)轉(zhuǎn)換器的精度問題。這都要求我們采取不同的措施來提高嵌入式模數(shù)轉(zhuǎn)換器的精度,。
　　1 精度與分辨率
　　ADC的精度和分辨率是兩個不同的概念,。精度是指轉(zhuǎn)換器實際值與理論值之間的偏差,；分辨率是指轉(zhuǎn)換器所能分辨的模擬信號的最小變化值。ADC 分辨率的高低取決于位數(shù)的多少,。一般來講,，分辨率越高，精度也越高,，但是影響轉(zhuǎn)換器精度的因素很多,，分辨率高的ADC，并不一定具有較高的精度,。精度是偏移誤差,、增益誤差、積分線性誤差,、微分線性誤差,、溫度漂移等綜合因素引起的總誤差。因量化誤差是模擬輸入量在量化取整過程中引起的,，因此,，分辨率直接影響量化誤差的大小，量化誤差是一種原理性誤差,，只與分辨率有關,，與信號的幅度，采樣速率無關,，它只能減小而無法完全消除,，只能使其控制在一定的范圍之內(nèi)，一般在±1／2LSB范圍內(nèi),。
　　1.1 偏移誤差
　　偏移誤差是指實際模數(shù)轉(zhuǎn)換曲線中數(shù)字0的代碼中點與理想轉(zhuǎn)換曲線中數(shù)字0的代碼中點的最大差值電壓,。這一差值電壓稱作偏移電壓，一般以滿量程電壓值的百分數(shù)表示,。在一定溫度下,，多數(shù)轉(zhuǎn)換器可以通過對外部電路的調(diào)整，使偏移誤差減小到接近于零,，但當溫度變化時,，偏移電壓又將出現(xiàn)，這主要是由于輸入失調(diào)電壓及溫漂造成的,。一般來說,，溫度變化較大時，要補償這一誤差是很困難的,。
　　1.2 增益誤差
　　增益誤差是轉(zhuǎn)換器輸出全“1”時，實際模擬輸入電壓與理想模擬輸入電壓之差,。它使傳輸特性曲線繞坐標原點偏離理想特性曲線一定的角度,，即增益誤差表示模數(shù)轉(zhuǎn)換特性曲線的實際斜率與理想斜率的偏差,，它的數(shù)值一般用滿量程的百分比來表示。
　　ADC的理想傳輸函數(shù)的關系式是
（1） 

式中Un是沒有量化時的標準模擬電壓,，由于存在增益誤差,，式（1）變?yōu)?br /> （2）
式中的K為增益誤差因子。當K＝l時,，沒有增益誤差,。當K＞1時，傳輸特性曲線的斜率變大,，臺階變窄,，在輸入模擬信號達到滿量程值之前，數(shù)字輸出就己全“l”狀態(tài),。當K＜1時,，傳輸特性曲線的斜率變小，臺階變寬,，輸入模擬信號己超滿量程值時,，數(shù)字輸出還未達到全“1”狀態(tài)輸出。
　　在一定溫度下,，可通過外部電路的調(diào)整使K＝l,，從而消除增益誤差。
　　1.3 線性誤差
　　線性誤差又稱積分線性誤差,，是指在沒有偏移誤差和增益誤差的情況下,，實際傳輸曲線與理想傳輸曲線之差。線性誤差一般不大于1／2LSB,。因為線性誤差是由ADC特性隨輸入信號幅值變化而引起的,，因此線性誤差是不能進行補償?shù)模揖€性誤差的數(shù)值會隨溫度的升高而增加,。
　　1.4 微分線性誤差
　　微分線性誤差是指實際代碼寬度與理想代碼寬度之間的最大偏差,，以LSB為單位，微分線性誤差也常用無失碼分辨率表示,。
　　由于時間和溫度的變化,，電源可能會有一定的變化，有時可能是造成影響ADC精度的主要原因,，因此在要求比較高的場合,，必須保證電源的穩(wěn)定性，使其隨溫度和時間的變化量在所允許的范圍之內(nèi),，但在一般的場合,，往往可以不考慮其對系統(tǒng)的影響。
　　2 嵌入式模數(shù)轉(zhuǎn)換器的結構及影響轉(zhuǎn)換的原因和消除方法
　　所謂嵌入式模數(shù)轉(zhuǎn)換器是指將模擬多路開關,、采樣保持,、A/D轉(zhuǎn)換,、微控制器集成在一個芯片上，經(jīng)常采用逐次比較型進行A/D轉(zhuǎn)換,，模擬輸入信號一般為非負單極性,，且輸入信號的電壓范圍為0～AVREF，A/D轉(zhuǎn)換器具有獨立的模擬電源與參考電壓,。
　　在實際應用中,，由于輸入信號的輸出電阻不同，如果輸出電阻過大,，會引起實際測量的電壓分壓過小,，因而引起測量值較實際值偏小,；或者由于輸入信號為雙極性模擬信號,，不能直接與嵌入式微控制器相連，必須采取特殊措施,，使雙極性模擬信號轉(zhuǎn)換為可以直接測量的非負單極性信號,；還有如果輸入信號幅值過大，以至于超過參考電壓,，也必須引入將壓環(huán)節(jié),，使輸入電壓低于參考電壓，等等,，下面對以上影響逐一進行分析,。
　　2.1 模擬輸入信號阻抗對采樣的影響
　　采樣過程是采樣電容充電，跟蹤輸入模擬信號電壓的過程,，由于采樣電路存在模擬多路開關阻抗,、采樣開關阻抗和輸入信號源阻抗，因此,，其轉(zhuǎn)換時間受模擬多路開關阻抗,、采樣開關阻抗與輸入信號源阻抗的影響，模擬多路開關與輸入信號源的阻抗越大則其轉(zhuǎn)換時間越長,。
  逐次比較型A/D的輸入端等效電路如下圖所示： 
 

圖1 逐次比較型A/D的輸入端等效電路

　　其中,，RIN為輸入模擬信號內(nèi)阻，VS為輸入模擬電壓信號,，RSH為模擬多路開關與采樣開關的等效電阻,，VSH為采樣電容的充電電壓，由等效電路可以看出,，輸入模擬信號內(nèi)阻越大,，則采樣電容充電時間越長，因此，對于采樣頻率要求越高的場合,，要求模擬輸入信號內(nèi)阻必須越小,，在應用時必須首先估算在規(guī)定的采樣頻率下，對模擬輸入信號內(nèi)阻的要求,。由電路理論可以求得RIN所允許的最大值（假設采樣時間為T）： 
 

　　如果信號源內(nèi)阻達不到要求，則需使用一個輸出阻抗很小的緩沖器,，例如可以使用電壓跟隨器,，使信號源的輸出阻抗達到A/D轉(zhuǎn)換器所要求的輸入阻抗的范圍之內(nèi)。
　　2.2 模擬信號極性及幅值的變換
　　在數(shù)據(jù)采集系統(tǒng)中,，采集的模擬信號并非都是非負單極性信號,，經(jīng)常是雙極性信號，因此在使用嵌入式A/D轉(zhuǎn)換器的時候,，需要對模擬輸入信號進行極性轉(zhuǎn)換,，我們可以采用運算放大器組成的線性網(wǎng)絡來對其極性及幅值進行轉(zhuǎn)換，但須注意的是在引入線性網(wǎng)絡的同時,，又引入了一定量的非線性誤差,，其線性網(wǎng)絡原理圖可用下圖表示：  
 

圖2 線性網(wǎng)絡原理圖

　　只要改變電阻R1、R2,、R3的大小以及它們的比例關系便可調(diào)整模擬輸入信號的大小使其符合測量要求,。
　　下面介紹一種常用的芯片AT90S8535關于其A／D轉(zhuǎn)換器使用時應該注意的情況。
　　AT90S8535是ATMEL公司生產(chǎn)的一款基于AVR RISC結構的,，低功耗的8位單片機,，其內(nèi)部集成有模數(shù)轉(zhuǎn)換器，模數(shù)轉(zhuǎn)換器具有以下特點：
　　　10位分辨率,；
　　　±2LSB精確度,；
　　　0.5LSB集成線性度；
　　　65～260μs轉(zhuǎn)換時間,；
　　　8通道,；
　　　自由運行模式和單次轉(zhuǎn)換模式；
　　　ADC轉(zhuǎn)換結束中斷,；
　　　休眠模式噪聲消除,。
　　AT90S8535具有10位分辨率的逐次逼近型A／D轉(zhuǎn)換器。ADC與一個8通道模擬多路器相連,，這樣就允許A口作為ADC的輸入引腳,。ADC包含一個采樣保持放大器，ADC框圖如下所示：

 
 
圖3ADC框圖

　　ADC可以工作于兩種模式——單次轉(zhuǎn)換和自由運行,。在單次轉(zhuǎn)換模式下,，用戶必須啟動每一次轉(zhuǎn)換，而在自由運行模式下，ADC會連續(xù)采樣并更新ADC數(shù)據(jù)寄存器,。ADCSR的ADFR位用于選擇A／D轉(zhuǎn)換器的運行模式,。
　　由于模擬通道的轉(zhuǎn)換總是要延遲到轉(zhuǎn)換的結束，因此,，自由運行模式可以用來掃描多個通道,，而不中斷轉(zhuǎn)換器。一般來說,，ADC轉(zhuǎn)換結束中斷用于修改通道,，但需考慮一下因素；結果一旦準備好,，中斷就被觸發(fā),，在自由運行模式，中斷一被觸發(fā),，則下一次轉(zhuǎn)換馬上開始,。如果中斷觸發(fā)過后，模擬通道改變,，而下一次轉(zhuǎn)換已經(jīng)開始,，則仍舊使用以前設置。
　　3.1 ADC噪聲消除技術
　　AT90S8535的內(nèi)外部數(shù)字電路會產(chǎn)生電磁干擾,，從而影響模擬測量精度,。如果要求測量精度較高，則應采取如下技術以減少噪聲：
1)　　AT90S8535的模擬部分及其他的模擬器件在PCB板上要有獨立的地線層,。模擬地與數(shù)字地單點相連,；
2)　　使模擬信號通路盡量短。使模擬走線在模擬地上通過,，并盡量保持遠離高速數(shù)字通路的走線,；
3)　　AVCC要通過一個RC網(wǎng)絡連接到VCC；
4)　　利用ADC的噪聲消除功能減小來自CPU的噪聲,；
5)　　如果A口的一些引腳作數(shù)字輸出口,，則在ADC轉(zhuǎn)換過程中，這些口不要改變其狀態(tài),。
　　3.2　ADC噪聲消除功能的實現(xiàn)
　　ADC可以在CPU空閑模式下進行轉(zhuǎn)換,，這一特征使得可以抑制來自CPU的噪聲。為了實現(xiàn)這一特性,，需采取一下措施：
  A)　　必須選擇單次轉(zhuǎn)換模式,，ADC的轉(zhuǎn)換結束中斷必須使能；
ADEN=1;ADSC=0;ADFR=0;ADIE=1;
  B)　　進入空閑模式,。一旦CPU停止,，則ADC將開始轉(zhuǎn)換；
  C)　　如果在ADC轉(zhuǎn)換結束之前沒有發(fā)生其它中斷，則ADC中斷將喚醒MCU并執(zhí)行ADC轉(zhuǎn)換結束中斷,。

  微控制器片內(nèi)A/D轉(zhuǎn)換器由于自身的結構,、性能特點，在許多應用中會遇到與獨立A/D轉(zhuǎn)換器不同的問題,，但大多數(shù)嵌入微控制器的A/D器都具有像AT90S8535相似的結構和特點,，采取的消噪技術和方法也大致相同，我們需根據(jù)具體情況具體分析需采取嵌入A/D還是獨立A/D,，并根據(jù)具體需求采取必要的措施來提高A/D轉(zhuǎn)換器的精度,。