1. In a reconfigurable programmable digital filter structure suitable for use as a deghosting filter; wherein said structure includes first and second input-weighted digital filter means each of which has a given number of multiplier-coefficient taps; a combination comprising: input means for providing input signals to said digital filter means; filter-reconfiguration means including multiplexer means coupled to said digital filter means (1) for configuring said first and second digital filter means for operation as a single complex digital filter means with said given number of complex multiplier coefficients for a complex sampled input signal provided thereto by said input means, or (2) for configuring at least one of said first and second digital filter units for operation as a separate real digital filter means with twice said given number of real multiplier coefficients for a real sampled input signal provided thereto by said input means; and output means for receiving output signals from said digital filter means.