The invention provides a system and method for measuring vital signs (e.g. SYS, DIA, SpO2, heart rate, and respiratory rate) and motion (e.g. activity level, posture, degree of motion, and arm height) from a patient. The system features: first and second sensors configured to independently generate time-dependent waveforms indicative of one or more contractile properties of the patient's heart; and a cuff-based oscillometric module. A processing component, typically worn on the patient's body and featuring a microprocessor, receives the time-dependent waveforms generated by the different sensors and processes them to determine patient-specific calibration values for use in a continuous blood pressure measurement based on pulse wave velocity (PWV).