Slave clock generation system and method for synchronous telecommunications networks
US6121816A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 1999 |
| Grant date | Sep 19, 2000 |
| Priority date | — |
| Expiry date | Apr 23, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F1/10
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A slave clock generation system and method suitable for use with synchronous telecommunications networks generates one or more slave clocks from a selected reference clock using a direct digital synthesis technique. A multiplexer selects a reference clock from a number of available sources, each of which can be at its own spot frequency, based on a predetermined selection order. Toggle detectors monitor each of the available clock sources, and block the selection of any that are not within a specified frequency range. A local oscillator establishes short-term and long-term measurement periods; the cycles of the selected reference clock are counted over consecutive short-term measurement periods to determine the relative frequency of the selected clock with respect to the frequency of the local oscillator. The cycle counts are fed to a phase-to-clock converter, which produces a slave clock output having a frequency that varies with the relative frequency measured for the selected clock. Rounding errors are countered by monitoring both the generated slave clock and the selected reference clock over a long-term measurement period, with the difference between these two cycle counts use…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.