AEMC OX III Series User Manual

Oscilloscope Mode - The "Horizontal" MenuIV - 78 SCOPIXOscilloscope Mode (cont'd)Min/MaxAcquisition Use this mode to view the extreme values of the signal acquired between2 acquisition memory samples.This mode:• detects wrong representation due to under-sampling• displays short-term events (Glitch, ≥ 2 ns).Whatever time base is used and the corresponding sampling speed, short-term events (Glitch, ≥ 2 ns) are displayed.* The " 9 " symbol indicates that the "Min/Max Acquisition" mode is active.AveragingNo averagingAverage rate 2Average rate 4Average rate 16Average rate 64Selection of a coefficient to calculate an average for the displayed samples.For instance, this is a way of attenuating random noise observed in a signal.For the averaging coefficient to be taken into account for representation of thesignal, the "Repetitive signal" option must be selected.The calculation is performed using the following formula:Pixel N = Sample*1/Average rate + Pixel N-1 (1-1/Average rate)with:Sample Value of new sample acquired at abscissa tPixel N Ordinate of pixel with abscissa t on the screen, at moment NPixel N-1 Ordinate of pixel with abscissa t on screen, at moment N-1* The "9" symbol indicates the averaging coefficient selected.FFT(Fast FourierTransform)*The Fast Fourier Transform (FFT) is used for calculating the discreterepresentation of a signal in a frequency domain from its discreterepresentation in the time domain.FFT can be used in the following applications:• measurement of the different harmonics and the distortion of a signal,• analysis of a pulse response,• search for noise source in logic circuits.The FFT is calculated over 2500 points.The Fast Fourier Transform is selected by the FFT icon in the control area.When the trace is zoomed, the FFT applies to the zoomed part of the trace(next to the time base adjustment).Description The Fast Fourier Transform is calculated using the equation:X (k) = 1 222 1N x n j nkNn NN* ( ) * exp −⎛⎝⎜ ⎞⎠⎟= −−∑ π for k ∈ [0 (N – 1) ]with: x (n): a sample in the time domainX (k): a sample in the frequency domainN: resolution of the FFTn: time indexk: frequency indexThe displayed trace represents the amplitude in V or dB of the various signalfrequency components according to the scale selected (linear or logarithmic).The DC component of the signal is removed by software.www.ShopAEMC.comShop for AEMC products online at: 1.877.766.5412