  Due to its conceptual simplicity and its proven effectiveness in real-time
detection and removal of radio frequency interference (RFI) from radio
astronomy data, the Spectral Kurtosis (SK) estimator is likely to become a
standard tool of a new generation of radio telescopes. However, the SK
estimator in its original form must be developed from instantaneous power
spectral density (PSD) estimates, and hence cannot be employed as an RFI
excision tool downstream of the data pipeline in existing instruments where any
time averaging is performed. In this letter, we develop a generalized estimator
with wider applicability for both instantaneous and averaged spectral data,
which extends its practical use to a much larger pool of radio instruments.
