| 摘要 |
A pulse oximeter has several processing channels for measurement signals which are measured during the switched-on phase of transmission diodes and which are used to determine the oxygen saturation (SpO2) of a patient. An additional measurement channel processes an ambient light signal which was measured while the transmission diodes were switched off or their intensity modified, in the same way and thus provides a measure of the spectral composition of the ambient light interference. A useful-to-noise-signal ratio (NSV) is derived from the ambient light signal and a measurement signal, which represents a measure of the signal quality and which can be compared with threshold values (G), where an alarm is triggered if the value falls below the threshold values.
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