There are some simple rules that will enable the cable telephony operator to meet and exceed PSTN voice quality. Place GPS PRSs with holdover clocks in all headend locations. Follow the BITS concept at all locations where sync is deployed. If practical, deploy a PRS at all CTMSs. It is recommended that one refer to the key telecommunications synchronization standards as illustrated in Figure 1 for a detailed review of common synchronization practices and associated equipment.
Synchronization is required for new VoIP cable telephony and digital video services.
Fortunately, synchronization equipment has evolved with GPS technology, enabling lower-cost components and simple installations everywhere capable of producing highly accurate signals traceable to the national standard. All these tools are available to provide PSTN QoS for cable multiservice networks. Ed Butterline is a technical consultant with Symmetricom. Once a cable TV network operator decides to step up, move into the digital arena and give the legacy telephone carrier a run for the money, synchronization needs to be part of the plan. Generic analog TV doesn t need sync.