PDH hardware is designed for transmission of Е1 flows via one single-mode optical fiber at distance up to 60 km. One system is capable to transmit from 2 to 16 E1 flows, as well as arranges service traffic and Ethernet channel. Reception and transmission are performed at different lengths of waves. Media converters operate as per point-point circuit. They are performed in 19” case and have double supply system -48 V and 220 V. We also provided light system of indication of emergencies and various modes of operation that provides quick diagnostics.