The motivation to control and temporarily isolate a single quantum mechanical event like an electronic transition has driven the quest for ever shorter light pulses. Controlling a highly intense electric field in the visible to infrared wavelength range on a sub-cycle time scale becomes feasible with the concept of the parametric waveform synthesizer. High harmonic generation(HHG) is explored as a primary application with the aim to generate isolated attosecond pulses and high photon energies in the "Water Window" spectral region from 284 eV to 533 eV. The tight synchronization of pulses from optical parametric amplifiers (OPAs) spanning from 650 nm to 2200 nm is achieved with long-term synthesized waveform stability. To work out and monitor the ideal synthesis parameters, a set of characterization methods are developed in the time and spatial domain.