The IT9100 filters out unwanted frequency components from the signal to improve the purity of the waveform, thereby increasing the accuracy of the test. The oscilloscope function of the IT9100 series power meter allows users to directly observe the fluctuations in the voltage, current, and power trend display when testing the performance of household appliances and can be set to display trends, waveforms, values, and histograms. Throughout the peripheral USB storage interface it directly captures the waveform and records the value, without the need for an external oscilloscope.