Photoplethysmographics using component-amplitude-division multiplexing
US5349953A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 5, 1991 |
| Grant date | Sep 27, 1994 |
| Priority date | — |
| Expiry date | Mar 5, 2011 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/1455
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A plurality of carrier signals, distinguishable by amplitudes of signal components (e.g., frequency components), are respectively applied to a plurality of energy emitters (e.g., infrared and red light emitters). A detector receives the sum of the energy after modulation at each emitter wavelength, e.g. by blood tissue of a patient. An output of the detector is then demultiplexed, whereby a component of modulation at each emitter wavelength may be determined. The carrier signals may comprise time-varying periodic signals with identical frequency and frequency components, such as mixtures of identical sets of pure sine waves. When the number of signal components exceeds the number of emitter wavelengths, sufficient information is provided during demultiplexing to detect and correct errors introduced by ambient light sources and other interference.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.