The single-input linearly varying gain factor model (LVGFM) is general
ised for the multiple-input single-output case. It is shown that the m
ultiple-input linearly varying gain factor model (MILVGFM) is a constr
ained form of the Volterra function model. The MILVGFM is much easier
to calibrate and to apply in practice than the second-order Volterra f
unction model for the case of multiple-input systems and yet its assoc
iated results are not significantly different from those of the latter
model.