Giving concrete digital-modulated form, the mean power spectrum density of the signals discussed can be obtained in this way. The calculation can be done on computers.

给定具体的数字调角形式，用这种方法可在计算机上计算所给信号的平均功率谱密度。

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But doing so will mean replacing high-power-density sources that are reliable and low cost with low-power-density sources that are highly variable and high cost.

FORBES: Magazine Article