  We investigate the performance of the generalized Spectral Kurtosis (SK)
estimator in detecting and discriminating natural and artificial very short
duration transients in the 2-bit sampling time domain Very-Long-Baseline
Interferometry (VLBI) data. We demonstrate that, while both types of transients
may be efficiently detected, their natural or artificial nature cannot be
distinguished if only a time domain SK analysis is performed. However, these
two types of transients become distinguishable from each other in the spectral
domain, after a 32-bit FFT operation is performed on the 2-bit time domain
voltages. We discuss the implication of these findings on the ability of the
Spectral Kurtosis estimator to automatically detect bright astronomical
transient signals of interests -- such as pulsar or fast radio bursts (FRB) --
in VLBI data streams that have been severely contaminated by unwanted radio
frequency interference.
