I have some noisy signal. When I substract real (for calibration it is known) or filtered signal I get residuals. When I plot distribution of these residuals I see that it is sum of exponential and Gaussian distributions. Is it possible to speculate about what does it means? Maybe it is common situation? Could you help me with explanation?
Your side-lobes appear to be approximately at +/- twice your signal amplitude, i.e. when the two signals are 180 degrees out of phase (peak of one = trough of the other). The prevalence likely arises because the blue signal is much higher frequency than the red, so the blue signal goes through several cycles over any interval where the slower red signal is near a peak/trough.