Patent ID: 8172764

Claim:
A method for determining a plurality of temporal reference points within a quasi-periodic signal comprising the steps of: acquiring ( 304 ) a first quasi-periodic signal, the first quasi-periodic signal having a low temporal resolution, and a high signal-to-noise ratio; acquiring a second quasi-periodic signal, the second quasi-periodic signal being related to the first quasi-periodic signal, and having a high temporal resolution, and a low signal-to-noise ratio; determining ( 310 ) a nominal interval of the first quasi-periodic signal by determining a most common frequency component of the first quasi-periodic signal; constructing and providing ( 312 ) a shape filter for the first quasi-periodic signal using the nominal interval for determining ( 320 ) slope crossings; forming ( 324 ) a template for the first quasi-periodic signal; identifying ( 328 ) reference time points for the first quasi-periodic signal by comparing the template with the first quasi-periodic signal; providing ( 330 ) an envelope for the second quasi-periodic signal using the reference times; estimating ( 336 ) reference points for the second quasi-periodic signal within the envelope; forming ( 342 ) a second template for the second quasi-periodic signal; cross-correlating ( 346 ) the second template with the second quasi-periodic signal around the reference points resulting in a highest correlation peak ( 350 ); and setting ( 352 ) the reference points to the time of the highest correlation peak.