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Determination of Time Delay Using Cross Correlation Disclosure Number: IPCOM000018474D
Original Publication Date: 2002-Sep-01
Included in the Prior Art Database: 2003-Jul-23
Document File: 1 page(s) / 175K

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Åke Larsson: AUTHOR



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As can be seen from the insert of Fig.1 that shows indetail the ringed region, the output from the expira-tion pressure sensor is delayed with respect to thatfrom  the  inspiration  pressure  sensor  by  a time, t d.This   time, t d  is determined in a digital data processorfrom  a  cross  correlation  of  the  two  curves (1,2).Usefully, data processing may be limited to a timewindow during  which  large  pressure  changes  areexpected to be measured, for example at the begin-ning (t 0 ) or the end (t 1 ) of an inspiration phase. Thedata  processing  system  employed  to  perform thecross-correlation is therefor preferably operablyconnected  to  the  ventilator  so  as  to  collect and/oranalyse data from the pressure sensors in dependenceof signals from the control system of the ventilatorthat are provided in a timed relation with the opera-tion of the ventilator.

Determination of Time Delay UsingCross Correlation

Idee: Åke Larsson, SE–Solna


Pressure sensors are usually found in both the inspi-ration and the expiration branches of the gas flowcircuit in a patient ventilator system. At any time inthe breathing cycle there will exist a time delay be-tween pressure sensed by the different sensors. Forexample, during an inspiration phase the expirationsensor  will  measure  a  signal  that is delayed withrespect to that measured by the inspiration sensor. Aventilator is typically regulated using the combinedcontemporaneous outputs of these sensors, w...