Systems and methods of this invention display data using pixels with information indicated by color and intensity changes, particularly used for monitoring of physiological variables in real time. The filter is a longitudinally coupled resonator type surface acoustic wave filter using an SH type surface acoustic wave, which has first and second grooves formed in a piezoelectric substrate at the top surface thereof so as to be substantially parallel to each other and spaced from each other by a predetermined distance. Otherwise, if the late slack value is not less than zero, the method restricts the early proxy slack value to a maximum of the early slack value and the negative of the late slack value.