SEL SP–157 - acoustic and vibroacoustic protection system of speech information
System is a technical mean of information protection, intended for protection of premises from soliciting through walling and engineered technical communications. Operating principle is based on forming wideband acoustic and vibroacoustic masking noise interferences consisting of analog white noise and speech-like noise (converted from digital). The system consists of a central generator unit and connected to it by wire passive electromagnetic (vibration) or electrodynamic (acoustic) transducers.
