Previous studies in animals, showed a different behavior between the variability of arterial pressure, arterial diameter and arterial elasticity when they were recorded during a couple of hours. On this basis, we proposed to advance in the simultaneous measurement of pressure and diameter of a central artery for 24 hours and provide new hypotheses on the variability of mechanical properties throughout the day. To that end, we have recently developed a prototype of an autonomous and portable device that allows continuous acquisition of physiological signals throughout the day, storing them in solid state memory for later analysis. In this paper we present the used methodology and the tuning of the implemented system, and first results obtained by recording continuously for 24 hours in a sheep, signals of pressure and aortic diameter, as well as pulse wave velocity as an indicator of arterial stiffness. Results using the here presented methodology encourage the realization of an experimental series in sheep aimed to study the variability of the arterial mechanical properties in 24 hours.