A decoder of a data signal subjected to phase shifting keying modulation uses an inner decoder for short block codes within a phase locked loop which is adapted to process the data signal with multiple initial phasefrequency error estimates and to output sets of codewords and phasefrequency error estimates respectively corresponding to the initial phasefrequency estimates. A direct digital synthesizer generates a waveform having intermediate angular changes during a transition time between symbol intervals. In another aspect, unwinding of the target power level is detected, after which the target power level is determined without considering wind-up. A displaybox can be created that distinguishes an area of the viewbox from the remainder of the display, which corresponds to content in the viewbox that would be displayed in normal zoom if the scroll handle were released at that location. 6 and a flow coefficient greater than or equal to 0.