An absorbing wave maker operated by means of on-line signals from digital FIR filters is presented.

Surface elevations are measured in two positions in front of the wave maker. The reflected wave train is seperated by the sum of the incident and reflected wave trains by means of digital filtering and subsequent superposition of the measured surface elevations. The motion of the wave paddle required to absorb reflected waves is determined and added to the original wave paddle control signal.

Irregular wave tests involving test structures with different degrees of reflection show that excellent absorption characteristics have been achieved with the system.