A novel measurement and post-processing technique for estimating if impulsive noise is capable of degrading the performance of digital communication systems (DCS) is presented. It is based on the well-known capability of the amplitude probability distribution (APD) to estimate the bit-error-rate of digital communication system in the presence of electromagnetic interferences. However, the APD shall be computed from measurements taken in the absence of the useful signal of the communication system, which is a strong handicap for in-situ measurements. The main contribution of the work presented is the combination of time domain EMI measurements and decomposition techniques for separating the impulsive noise from the narrow band signals of the digital communication systems. Therefore, although the communication system signal is present at the test site, the APD diagram is obtained without the influence of the communication system, which is crucial to directly relate the shape of the diagram with the bit-error-rate introduced by the impulsive noise. This is an important step forward compared with the traditional approach as it offers the possibility to study the impact of impulsive interferences although DCS, such as broadcasting services, are present at interference scenarios.