A pixel-data processing circuit delivers a fixed number of pixels to a video processing stage using an irregular sampling pattern that is defined by a variably-definable sampling window. The tank may have two compartments, one above the other, formed by a separating baffle. The drain and source electrodes are on a first face of the layer of semiconductor at locations that are spaced apart on either side of a channel. The estimations of the transmitted, symbols are obtained based on a threshold relating to the phase of the received symbol which is compensated in phase, in the case of a modulation of the PSK type. The water soluble containers can be made by thermoforming or injection molding.