Synchronous Ethernet (SyncE) is one of the standards developed to enable synchronization in packet networks through physical layer frequency synchronization. Another standard is precision time protocol (PTP) defined by IEEE 1588 that enables frequency, phase and time synchronization through any packet network. In both SyncE and PTP applications, the local oscillator is a key component that has a direct impact on the quality of the recovered clock or time. Network devices can be installed in different locations. Some may be in a stable indoor-temperature environment, and others might be mounted in outdoor boxes that are exposed to harsh conditions. Local oscillators must deliver a high-quality, stable reference regardless of environmental factors.
Oscillator datasheets guarantee performance specifications under ideal operating conditions including controlled still air environment without any temperature transients of airflow, no vibration, and stable supply voltage. These ideal conditions do not exist in real-world applications and the performance of a TCXO subjected to these environmental stressors is unknown. A common performance risk mitigation strategy is to remove the stressors.
While considered good design practices for precision quartz TCXOs, these techniques make the design more difficult, restrictive, and expensive. A better way to solve the problem is to use an oscillator that is not sensitive to environmental stressors and can maintain the same level of performance regardless of operating conditions. This reduces the risk of performance degradation, simplifies system design, and reduces cost.