Fig. 1

The operating window of the SWIRD detector within the solar irradiation. The difference between the terrestrial (red) solar spectral irradiance (ASTM G-173-03) and the extraterrestrial (blue) spectrum (ASTM E-490) is due to the attenuation of the signal by the atmosphere. There are areas where the electromagnetic radiation of the sun is almost completely absorbed. This is what makes tracking possible. The operating window (cyan) (i.e. the range in which the receiver () is sensitive) is given due to the full width at half maximum (25 nm and the center wavelength (1400 nm)) of the utilized band pass filter