Method and apparatus for continuously measuring volumetric flow
US5146414A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 18, 1990 |
| Grant date | Sep 8, 1992 |
| Priority date | — |
| Expiry date | Apr 18, 2010 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/7257
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
Method and apparatus for adapting the volumetric flow rate measurement system taught by Yelderman in U.S. Pat. No. 4,507,974 to clinical environments by reducing the effects of physiological noise. Signal processing techniques are used to characterize the background noise power spectrum of the system under test so that the effect of noise aberrations on the measured data may be eliminated and so that the predominant periodicities of the background noise spectra may be avoided. The invention further cross-correlates the input data of the system with the corresponding ouput data of the system to determine weighting values for each input frequency so that data collected at noisy frequencies is discounted. Low frequency noise or drift is also removed from the output signal by fitting the average of the output data to a quadratic function which is then subtracted from the original output signal, point by point. Finally, the processed data is fit to a lagged normal normal distribution curve in the frequency domain to solve for the parameters necessary to mathematically model the transfer function of the system. Given the input to the system as well as the frequency domain transfer functi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.