FFT Analyzer Basic FAQ

リアルタイム周波数レンジより低い周波数レンジにおいては、新たにFFT処理する時間窓での時間データが1つ前の時間データと1部だけ同じデータとして処理することが可能となります。このように時間窓を重ねて平均処理することをオーバラップ処理と呼びます。

The amount of overlap depends on the processing power of the FFT analyzer and the frequency range (or the length of the time window being captured). If the frequency range is around 1 kHz or less, the default setting (Max Overlap) will not allow much new time data to be incorporated into the averaging process, so you will need to set the overlap amount. For typical Hanning window settings, an overlap of around 50% is appropriate.

There are two ways to set how much averaging is performed: by the number of averaging cycles and by the averaging time. Setting it by averaging time allows for sufficient averaging without having to worry too much about the amount of overlap.

	Overlap processing (FFT basic terminology glossary)