1. An apparatus, comprising: an input interface configured to provide signals from at least two sensors for at least two positions of the subject, including: signals, dependent upon blood presence, from the first sensor when the subject is in a first position signals dependent by the presence of blood, from the first sensor when the subject is in a second position signals, depending on the presence of blood from the second sensor when the subject is in a first position, isignaly dependent on the presence of blood from the second sensor when sous The object is in the second position, iobrabatyvayuschuyu circuitry configured to determine and output a metric by combining said signals provided according to a predetermined calibration dannym.2. The apparatus of claim 1, wherein the signals for each combination of sensor and position comprise at least one logarithm of detected sveta.3 intensity. The apparatus according to claim 1 or 2, wherein the signals for each combination of sensor and position comprise: a) a component detected light intensity which varies in time and the quasi-static component of the detected light intensity and / or b) the logarithm of a time varying component of detected light intensity and a logarithm of a quasi-static component of the detected light intensity and / or c) signal based on a signal intensity of light detected by the optical reflection sensor and a signal based on the light intensity signal detected by a sensor of the optical transmission and / or d) a signal based on the light intensity signal detected at a first wavelength, but not at the second wavelength1. Устройство, включающее:входной интерфейс, сконфигурированный для предоставления сигналов по меньшей мере от двух датчиков по меньшей мере для двух положений субъекта, включая:сигналы, зависящие от наличия крови, от первого датчика, когда субъект находится в первом положениисигналы, зависящие от наличия крови, от первого датчика, когда субъект находится во втором положениисигнал
