IEC 61920-2004 pdf – Infrared free air applications.
1 Scope and object This International Standard describes the classification of IR devices into groups and classes in order to identify and clarify problems caused by mutual interference. Mutual interference is caused by the increasing parallel application of different infrared (IR) systems. Due to its physical characteristics, the possibility of local limitation is a special feature of IR radiation. In this standard, the wavelength range from 700 nm to 1 600 nm is considered. All systems based on free air application which intentionally or unintentionally use IR radiation in this range, are included. Products which unintentionally emit IR radiation, such as illumination equipment are not deemed to be IR application systems. They are, however, integrated into this standard in order to enable facility planners to take into consideration and to foresee provisions against disturbance of IR application systems by such unintentionally emitted radiation. The object of this standard is to prevent or at least to minimize mutual interference and to allow the coexistence of different IR products. It is intended to identify each IR product by its characteristics, according to the classification criteria. It is not the object of this standard to describe the consequences of interference between IR systems or safety aspects of optical radiation. All applications of fibre-optic technology are excluded. In this context “free air” means freely radiated IR in indoor or outdoor applications. If the IR systems are used for information transmission, this standard is only relevant in connection with the physical layer of the open systems interconnection (OSI) reference model (ISO 7498-1). NOTE The reader should be aware that a risk of interference between different infrared systems as assessed by this standard is based on general parameters and therefore cannot take all the parameters involved into account.
3.5 interference disturbance experienced in the reception of a wanted signal, caused by an unwanted signal or noise 3.6 infrared radiation optical radiation for which the wavelengths are longer than those for visible radiation [IEV 845-01-04] NOTE For infrared radiation, the range between 780 nm and 1 mm is commonly subdivided into: IR-A 780 nm to 1 400 nm; IR-B 1,4 µm to 3 µm; IR-C 3 µm to 1 mm. 3.7 infrared system system which uses IR radiation in free air application consisting of IR radiator and IR receiver 3.8 irradiance E irradiance (at a point of a surface) is the quotient of the radiant flux d Φ e incident on an element of the surface containing the point, by the area dA of that element E = d Φ e /dA NOTE Irradiance is expressed in [mW/m²]. [IEV 845-01-37] 3.9 modulation frequency electrical signal frequency which modulates the IR radiation 3.10 peak intensity I p maximum intensity I p [mW/sr] of the optical radiation inside the optical radiation pattern NOTE It should be taken into account that a different radiation pattern may occur in different wavelength ranges in the same application.
5 Classification 5.1 General The classification considers four main aspects for description of IR systems consisting of radiators and receivers: – physical characteristics of radiators (see 5.2); – physical characteristics of receivers (see 5.3); – product groups (see 5.5); – user areas (see 5.6). 5.2 Physical characteristics of radiators 5.2.1 General There are five criteria, 1 to 5, on which the classification for physical characteristics of radiators is based. They are operating characteristics, selected from the rated values given by the manufacturer (see Table 1). 5.2.2 Ranges of wavelength (criterion 1) The lower ( λ 1l ) and the upper ( λ 1u ) optical wavelengths determine the optical range of an IR radiator. Both the lower and the upper optical wavelengths of an IR radiator are defined by the reduction of the peak intensity I p λ by 3 dB, taking into account the effects of temperature and component deviations (see Figure 2).