Masimo Set Technology - Datascope Accutorr Plus Service Manual

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2.2.11 Masimo SET Technology
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Masimo SET Technology, combines advances in fundamental sensor technology, digital
signal processing, an easily portable platform and a low noise hardware platform
incorporating multiple wavelengths applicable to many physiological parameters.
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Masimo's SET Technology is composed of three components; (1) new signal processing
apparatus, (2) a new method for invivo measurement, and (3) new sensor technologies.
The main benefit of Masimo's technology is the effective cancellation of unpredictable
"in-band noise" (noise which is in the same frequency, phase and/or amplitude space as
the desired signal).
Conventional fixed filters, whether analog or digital form, have been designed to pass
certain frequencies while rejecting others. For example, a bandpass filter with a lower
cut-off frequency of 1hz and an upper cut-off frequency of 10Hz will pass all frequencies
between 1hz and 10Hz and reject frequencies below 1hz and above 10Hz. Therefore, any
"noise" that has a frequency outside the pass band is rejected and not considered
(i.e. 120Hz due to room light and 60Hz noise from electrical lines). However, if noise
exists between the pass band of 1hz and 10Hz it will enter the system with the desired
signal and corrupt the measurement (i.e. patient motion at 2Hz). Fixed filters will always
have this limitation.
Masimo has overcome these problems by developing a novel technique to accurately
determine the noise reference (patents issued and pending); thus, making adaptive filters
work in real-time even when applied to medical monitoring of widely variable and
unpredictable patients. With this new technique, Masimo is able to solve the perennial
problem of motion artifact in pulse oximetry.
Masimo licenses this technology to Datascope. Further technical information is available
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from Masimo on the Internet at www.Masimo.com.
Accutorr Plus Service Manual 2-31
Revised 12/20/00
Chapter 2 - Theory of Operation