ABSTRACT: The digital synchronization network consists of clocks connected by digital facilities. This document provides criteria that apply to these various clocks deployed in telecommunications equipment such as transport Network Elements (NEs), Digital Switches, and Timing Signal Generators (TSGs). Since these clocks can have a critical impact on network performance, GR-1244 may be of significant value to telecommunications equipment manufacturers (including both synchronization-related component and system manufacturers) and telecommunications service providers.

The updates in Issue 4 should significantly assist the reader's understanding of the criteria (and expected clock performance characteristics) in areas such as holdover stability, wander generation, and phase build-out. Specific updates include:

• The equations for calculating fractional frequency offset and drift were corrected, and additional information on the use of those equations was provided
• The temperature component of the holdover frequency stability requirement for stratum 3 clocks was changed to align with the corresponding specification in ATIS-0900101
• Significant explanatory test was added regarding the holdover stability curves provided in Section 5
• Additional explanatory text was provided regarding the conditions under which the wander generation requirements apply
• The proposed value of one of the parameters used in defining test cases for testing a clock's phase build-out performance was changed to reflect the long time constants of the filters used in stratum 2 and 3E clocks
• Additional information was provided regarding the applicability of various criteria to NEs/clocks used in SONET or "synchronous Ethernet" applications.