Sonifex AVN-GMCOS - OCXO IEEE1588 PTP Grandmaster Clock with GPS ReceiverAVN GMCOS OCXO Oven Controlled Oscillator accurate to 0. 1 parts per million (worst case 1 sec gain loss every 115 days) The AVN GMCS is a PTPv2 grandmaster clock for use with AoIP applications. IEEE1588 2008 PTPv2 (precision time protocol) is used to synchronise all the nodes within a network. To achieve this one of the nodes must become the master clock and distribute time packets to the others. The AVN GMCS is designed to perform this role simply