A DIGITAL APPROACH TO AUTOMATIC-CONTROL OF A LONG-BASE-LINE INTERFEROMETRIC ANTENNA FOR GRAVITATIONAL-WAVE DETECTION

A digital control system is probably the best technical solution to th e problem of automatic control of the Virgo interferometric antenna fo r gravitational wave detection, provided that very critical specificat ions concerning residual noise introduced by the digital system in the measurement band are met. For this purpose, a model of the digital sy stem has been developed and tested to quantify the main sources and le vels of noise. Experimental measurements, obtained using a prototype o f the automatic control system, and theoretical analysis of the perfor mances of the digital control loops have demonstrated the feasibility of a digital control system.