Patent ID: 6911009

Claim:
A sphygmogram measure method for measuring pulse pressure at two adjacent measure points, comprising the steps of: Step 1: positioning an upstream pressure sensor and a downstream pressure sensor at a certain distance L in accordance with the bloodstream direction; Step 2: acquiring the signals from the upstream and the downstream pressure sensors and passing the signals through preamplifier and filter circuits and offset adjust circuits to acquire an analog form of upstream pressure P 0 (t) and downstream pressure P L (t); Step 3: converting the analogy analog form of upstream pressure P 0 (t) into a digital upstream pressure P 0 (n) using an A/D converter at a sampling frequency of 200 to 400 Hz and then storing the digital upstream pressure into a digital signal process unit; Step 4: filtering the analog form of upstream pressure P 0 (t) and downstream pressure P L (t) by two low-pass filters to obtain their fundamental waves; Step 5: detecting the zero-cross signal of the fundamental wave of the upstream and downstream pressure signals to trigger and stop the counting of a counter, and obtaining the time lag τ between the two pressure signals by output of the counter: Step 6: storing the digitized upstream pressure signal P 0 (t) and time lag τ in the digital signal process unit; and Step 7: calculating the digital downstream pressure P L (n) in the digital signal process unit by using the digital upstream pressure P 0 (n) and time lag τ, where P L (n) P 0 (n+τ).