System for detection and localization of impedance mismatches in SMATV-networks, which comprises: - a radio frequency input for receiving a signal in a point of the SMATV network; - a device for detecting energy of this signal; - a mixing stage for converting this signal; - a bandpass filter for filtering the converted signal; - an automatic gain control circuit for adapting the filtered signal; - an analog-to-digital converter for digitalization of the adapted signal; - a module for detection and localization of impedance mismatches (308, 311), which comprises: a first block configured for calculation of a spectrum of the signal digitized by the analog-to-digital converter; a second block configured for calculation of a module of the spectrum of the signal is; a third block configured to reduce the noise of the module of the spectrum of the signal; a fourth block configured to spectrum transform the noise-reduced module of the spectrum of the signal, wherein the spectrum transform comprises performing an operation (1041, 1042) with the noise-reduced module to the nth power; a fifth block configured for calculation of an inverse Fourier-transformed of the transformed noise-reduced module of the spectrum of the signal; a sixth block configured for calculation of a module to the n-th power of the inverse Fourier-transformed of the transformed noise-reduced module of the spectrum of the signal; and a seventh block configured to detect and localize impedance mismatches in the SMATV-network at the positions of maxima in the module to the nth power of the inverse Fourier transform of the transformed noise-reduced module of the spectrum of the signal. - a radio frequency input for receiving a signal in a point of the SMATV network; - a device for detecting energy of this signal; - a mixing stage for converting this signal; - a bandpass filter for filtering the converted signal; - an automatic gain control circuit for adapting the filtered signal; - an analog-to-digital converter for digitalization of the adapted signal; - a module for detection and localization of impedance mismatches (308, 311), which comprises: a first block configured for calculation of a spectrum of the signal digitized by the analog-to-digital converter; a second block configured for calculation of a module of the spectrum of the signal is; a third block configured to reduce the noise of the module of the spectrum of the signal; a fourth block configured to spectrum transform the noise-reduced module of the spectrum of the signal, wherein the spectrum transform comprises performing an operation (1041, 1042) with the noise-reduced module to the nth power; a fifth block configured for calculation of an inverse Fourier-transformed of the transformed noise-reduced module of the spectrum of the signal; a sixth block configured for calculation of a module to the n-th power of the inverse Fourier-transformed of the transformed noise-reduced module of the spectrum of the signal; and a seventh block configured to detect and localize impedance mismatches in the SMATV-network at the positions of maxima in the module to the nth power of the inverse Fourier transform of the transformed noise-reduced module of the spectrum of the signal. a first block configured for calculation of a spectrum of the signal digitized by the analog-to-digital converter; a second block configured for calculation of a module of the spectrum of the signal is; a third block configured to reduce the noise of the module of the spectrum of the signal; a fourth block configured to spectrum transform the noise-reduced module of the spectrum of the signal, wherein the spectrum transform comprises performing an operation (1041, 1042) with the noise-reduced module to the nth power; a fifth block configured for calculation of an inverse Fourier-transformed of the transformed noise-reduced module of the spectrum of the signal; a sixth block configured for calculation of a module to the n-th power of the inverse Fourier-transformed of the transformed noise-reduced module of the spectrum of the signal; and a seventh block configured to detect and localize impedance mismatches in the SMATV-network at the positions of maxima in the module to the nth power of the inverse Fourier transform of the transformed noise-reduced module of the spectrum of the signal.