One of the sources of spurious signals in DDFS is the use of smaller number, W, of the most significant bits (MSB) applied for the output sine wave reconstruction from all R bits stored in the accumulator. The result is a phase modulation of the output signal. The problem was first solved by Nicholas et al. [1987-8] in a rather complicated way with the result that the level of the largest spurious signal is about -6 W dB below the carrier with an increase of 3.9 dB in some instances. The present paper investigates the validity and correctness of these generally cited results.
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机译:DDFS中伪信号的来源之一是使用较小的W个最高有效位(MSB)从存储在累加器中的所有R位应用到输出正弦波重构。结果是输出信号的相位调制。 Nicholas等人首先解决了这个问题。 [1987-8]以相当复杂的方式进行操作,其结果是,最大杂散信号的电平比载波低约-6 W dB,在某些情况下增加了3.9 dB。本文研究了这些被普遍引用的结果的有效性和正确性。
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