The reliable primary reference clock for the SDH optical telecommunication network

The mutually synchronized ensemble consisting of three primary reference clocks (PRCs), which is top level of the "oligarchic" synchronization network for SDH transport network supporting is proposed. This ensemble may be construed as an original PRC backup approach with not only "hot standby" but with effective use of equipment, because every PRC is active and contributes its stability in resulting reference. Moreover, the most unreliable part of the ensemble, that is backup switch selector, is excluded. The stability evaluation of the mutually synchronized ensemble is given