You clearly have considered this problem in some depth. It seems the best approach is to look at the filtered signal and go from there. Hopefully, there is some periodic threshold to 'latch' onto. Shawn >From: Benjamin Bromilow >Reply-To: pic microcontroller discussion list >To: PICLIST@MITVMA.MIT.EDU >Subject: Re: [PIC] Heart Rate/Pulse Monitor >Date: Mon, 27 May 2002 01:34:35 +0100 > >The main problem with the acoustic option that I can see is that it relies >on nice clean heart sounds. A heart murmur or diminished heart sounds (e.g. >due to a pericardial effusion) would result in a poor signal. Then again, >if >you had either of the above, you you would want to know more than your >exercising pulse rate!!! >Normally you'll get two noises per heart beat. Sometimes the second heart >sound can be split into two distinct peaks. This can vary with breathing. >So >the second heart sound would need an acoustic debounce if that makes any >sense... Other than that it should be fairly straightforward... >Ben > >-- >http://www.piclist.com hint: To leave the PICList >mailto:piclist-unsubscribe-request@mitvma.mit.edu _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu