David A Purdy

US Patent:

6472943, Oct 29, 2002

Filed:

Apr 13, 2001

Appl. No.:

09/834406

Inventors:

Anthony Chak Keung Soong - Superior CO
Bruce S. Schwartz - Boulder CO
Kate Jennings Lainson - Lafayette CO
David Purdy - Louisville CO

Assignee:

Telefonaktie Bolaget L.M. Ericsson - Stockholm

International Classification:

H03B 532

US Classification:

331 44, 331 74, 327105, 327291, 327513

Abstract:

An oscillating circuit ( ) includes a quartz crystal oscillator ( ) for generating a clock signal ( ). The clock signal is synchronized to a master signal ( ) during the lock-in periods when the oscillating circuit ( ) has access to the master signal ( ). During the holdover periods when the oscillating circuit ( ) loses access to the master signal ( ), an oscillation frequency function predicts the crystal oscillation frequency in terms the physical parameters, e. g. , time and temperature, that may affect the crystal oscillation frequency. The predicted frequency is compared with a standard frequency to generate an error signal. In response to the error signal, a fraction handler block ( ) determines whether adding cycles to or deleting cycles from the clock signal, thereby calibrating the oscillation signal ( ) of the oscillating circuit ( ).

US Patent:

7349501, Mar 25, 2008

Filed:

Jul 9, 2004

Appl. No.:

10/888452

Inventors:

Anthony C. K. Soong - Superior CO, US
David Purdy - Westminster CO, US
Larry Flowers - Westminster CO, US

Assignee:

Telefonaktiebolaget LM Ericsson (publ)

International Classification:

H04L 27/08

US Classification:

375345

Abstract:

A method and apparatus for automatic gain control of a receiver provides compensation of gain control operations for received signal disruptions. In one embodiment, an automatic gain control circuit remembers control state information from a time just before a given disruption, and uses it to reset the automatic gain control circuit at the end of the disruption, or to maintain the automatic gain control circuit during the disruption. The remembering function may be triggered, such by detecting an impending disruption, or done periodically at a high enough update rate that the remembered information is always current with respect to any given disruption. Thus, an exemplary automatic gain control circuit may generate a receiver gain control signal by filtering received signal power measurements, and compensate the generation of that gain control signal by capturing filter state information just prior to signal disruptions. Compensation may comprise resetting or freezing the filter.