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Emission-aware programming is a design philosophy aiming to reduce the amount of electromagnetic radiation emitted by electronic devices through proper design of the software executed by the device, rather than changing the hardware. ==Emission Sources== Emission considerations require the evaluation of many details such as the clock frequencies and switching rates which are related to the oscillator. Rise/fall times and signal harmonics are related to the output driver. The data transfer rates can be dependent on hardware or can be controlled by software and often have to meet a certain protocol. Impedances, trace loading and the various circuit components are hardware related and must be considered from the beginning of the design. Three basic actions for emission reduction can be defined: *Avoidance of unnecessary RF-noise. :Only this action can be applied to software based emission control. Reduction of for instance the switching frequency or the number of switching circuits reduces the power consumption and therefore the emissions. For example this could be low voltage operation or the usage of power reduction modes. *Keeping RF-energy insulated from antenna structures. :RF-energy is not a problem if the structures dealing with it are too small〔In RF-Engineering the unit of measurement is the wave length λ. Geometrical measures are taken as a multiple of the wave length. The geometrical distance ''d'' between two points are quantified in ''d''/λ. Thus terms like small or large are always related to wave length. Electromagnetically large structures accord to ''d'' >= 1 and small to ''d'' < 0.1 or ''d'' = λ/10. The range between electromagnetically small and large is the resonant frequency range.〕 for acting as effective antennas. A decoupling capacity keeps most of the RF-energy locally in a small loop between the device and the capacitor as shown in the figure. *Transforming RF-energy into heat. :Any impedance formed by coils, capacitors, resistors, ferrites etc. can be used for this purpose. In the following all components that can be influenced by the software design will be described. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Emission-aware programming」の詳細全文を読む スポンサード リンク
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