An emitter for emitting radiations at a specific wavelength which is the characteristic wavelength of a particular fluid, comprising: a Joule-heated emitting electrical conductor , configured to emit radiations at the specific wavelength at an emission temperature at which radiations at the specific wavelength are emitted, a controller configured, in operation, to control a variable voltage (v DD ) subjected to the Joule-heated emitting electrical conductor and modulated according to a duty cycle, the duty cycle being variable between: a high-average power duty cycle, during hot periods , so that the Joule-heated emitting electrical conductor is subjected to a high-average power to reach and maintain the emission temperature to emit radiations at the specific wavelength; and a low-average power duty cycle, during cold periods alternated to the hot periods , so that the Joule-heated emitting electrical conductor is subjected to a low-average power to reach a temperature smaller than the emission temperature so that the Joule-heated emitting electrical conductor does not emit, or emits only a negligible amount of, radiations at the specific wavelength, wherein the low-average power duty cycle is smaller than the high-average power duty cycle, characterized in that the controller is configured to obtain at least one temperature-indicative measured value indicative of the ambient temperature provided by a temperature sensor , wherein the high-average power duty cycle and the low-average power duty cycle are defined based on the at least one temperature-indicative measured value indicative of the ambient temperature as measured. a Joule-heated emitting electrical conductor , configured to emit radiations at the specific wavelength at an emission temperature at which radiations at the specific wavelength are emitted, a controller configured, in operation, to control a variable voltage (v DD ) subjected to the Joule-heated emitting electrical conductor and modulated according to a duty cycle, the duty cycle being variable between: a high-average power duty cycle, during hot periods , so that the Joule-heated emitting electrical conductor is subjected to a high-average power to reach and maintain the emission temperature to emit radiations at the specific wavelength; and a low-average power duty cycle, during cold periods alternated to the hot periods , so that the Joule-heated emitting electrical conductor is subjected to a low-average power to reach a temperature smaller than the emission temperature so that the Joule-heated emitting electrical conductor does not emit, or emits only a negligible amount of, radiations at the specific wavelength, wherein the low-average power duty cycle is smaller than the high-average power duty cycle, characterized in that a high-average power duty cycle, during hot periods , so that the Joule-heated emitting electrical conductor is subjected to a high-average power to reach and maintain the emission temperature to emit radiations at the specific wavelength; and a low-average power duty cycle, during cold periods alternated to the hot periods , so that the Joule-heated emitting electrical conductor is subjected to a low-average power to reach a temperature smaller than the emission temperature so that the Joule-heated emitting electrical conductor does not emit, or emits only a negligible amount of, radiations at the specific wavelength, wherein the low-average power duty cycle is smaller than the high-average power duty cycle, characterized in that the controller is configured to obtain at least one temperature-indicative measured value indicative of the ambient temperature provided by a temperature sensor , wherein the high-average power duty cycle and the low-average power duty cycle are defined based on the at least one temperature-indicative measured value indicative of the ambient temperature as measured. <EOS>