Abstract: A method for automatically identifying the source of fluctuations in a trans-ionospheric radio signal, by acquiring a portion of the radio signal and computing statistics on it, including mean, standard deviation, scintillation index, skew, kurtosis, decorrelation time, and spectral slope. The scintillation index, skew, kurtosis, decorrelation time, and spectral slope are compared to thresholds, and based at least in part upon the comparisons, at least one condition present in the portion of the radio signal is selectively indicated to an operator, where the condition is selected from the group of no signal fluctuations, RF interference, multipath interference, noise, and ionospheric scintillation.