System and method for increased accuracy in determining CPR chest compression depth in real time

A method of determining, using a processor, chest compression depth during CPR being performed on a patient or manikin, comprising:

• receiving an acceleration signal representing an acceleration value of the chest compression;
• filtering the acceleration signal at least once;
• double integrating the filtered acceleration signal;
• receiving and adjusting an independent reference signal to produce an adjusted reference signal;
• filtering the adjusted reference signal at least once to produce a filtered adjusted reference signal;
• determining, using a processor operatively coupled to receive the double integrated filtered acceleration signal, the filtered adjusted reference signal, and the adjusted reference signal, a compensation signal by subtracting the filtered adjusted reference signal from the adjusted reference signal;
• and
• determining, using the processor, the chest compression depth by adding the double integrated filtered acceleration signal and the compensation signal.