  This paper presents a detailed analysis of the applicability and benefits of
baseline dependent averaging (BDA) in modern radio interferometers and in
particular the Square Kilometre Array (SKA). We demonstrate that BDA does not
affect the information content of the data other than a well-defined
decorrelation loss for which closed form expressions are readily available. We
verify these theoretical findings using simulations. We therefore conclude that
BDA can be used reliably in modern radio interferometry allowing a reduction of
visibility data volume (and hence processing costs for handling visibility
data) by more than 80%.
