System and method for estimating clock error in a remote communication device
US5953648A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 13, 1996 |
| Grant date | Sep 14, 1999 |
| Priority date | — |
| Expiry date | Aug 13, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02D30/70
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a mobile telephone that includes an internal voltage controlled crystal oscillator clock, a clock error compensation system is provided that dynamically determines and compensates for clock error during periods in which the mobile telephone is asleep. The system drives the control voltage of the clock to one of the clock's voltage limits, at which limit the sleep error of the clock can be expected to occur. This expected sleep error is then added to the number of clocking pulses which, in the absence of any clock error, would correspond to the length of the desired sleep period, to generate a corrected internal time. At the end of the sleep period as determined by the corrected internal time, the mobile telephone reacquires a system timing signal that represents actual system time, and the corrected internal time is then compared to the system time. The difference between corrected internal time and actual system time is added to the expected sleep error for the next sleep cycle, with succeeding sleep cycles being progressively longer as the expected sleep error of the clock is recursively determined and applied to the output of the internal clock.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.