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From Friday, April 19th (11:00 PM CDT) through Saturday, April 20th (2:00 PM CDT), 2024, ni.com will undergo system upgrades that may result in temporary service interruption.
We appreciate your patience as we improve our online experience.
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頻率的精確度通常是用ppm表示(百萬分之ㄧ). 這可以利用簡單的公式換算成頻率的誤差: 頻率誤差=(取樣頻率*頻率精確度). 如果你的裝置使用25ppm的取樣時脈精確度和100KS/s的取樣頻率來對訊號做取樣,則時脈的精確度為 100,000(S)*25/1,000,000=2.5Hz.因此實際的取樣時脈就是100kHz±2.5Hz.
考慮你要量測一個實際值為1kHz的sine波.使用100kS/s的取樣時脈,則你量測的精準度為1,000*25/1,000,000=0.025Hz.因此對這個波的頻率量測的結果就是1 kHz ± 0.025 Hz.
Note: 你必須使用超過Nyquist頻率的取樣頻率來避免失真並確保能量測到正確的頻率.Nyquist頻率是你所量測訊號的最大頻率的兩倍.
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