Chip-Scale Atomic Frequency References
Nov 1, 2007
By:
John Kitching
|
New marvels of miniaturization — the fabrication and performance of chip-scale atomic frequency references — will be moving from the lab to the factory any day now.
Using Precise Point Positioning for Clock Comparisons
Nov 1, 2006
By:
François Lahaye, Diego Orgiazzi, Patrizia Tavella, Giancarlo Cerretto
|
One of the great technological accomplishments on the 18th century was the solution of "the longitude problem." Although latitude could be determined to high accuracy using astronomical observations and navigation tables alone, a determination of longitude additionally required knowing the time at Greenwich (Greenwich Mean Time or GMT) at the instant of the observations. Although astronomical techniques for determining GMT or time on some reference meridian had been developed as far back as the 1500s, they didn't provide sufficient accuracy and many marine disasters occurred because of inaccurately determined longitudes.
The National Security Space Office (NSSO) is gathering information on positioning, navigation, and timing (PNT) to develop an evolutionary path for a robust National PNT Architecture for the 2025 time period. Interested companies or organizations may present during meetings October 10-12 or October 17-18.
Synchronizing GSM Mobile Telephones to Microseconds
Jul 1, 2005
By:
Peter J. Duffett-Smith, Paul Hansen
|
A new Matrix positioning method provides precise-time aiding to terminals in un-synchronized communications networks.
GPS Harness for Large-Area Electrical Grid
Apr 1, 2005
By:
Dennis C. Erickson, Carson Taylor
|
A control system uses GPS to timetag with microsecond accuracy voltage and current measurements throughout a large-area power grid.
GPS-Galileo Offset Will Bias Position
Mar 1, 2005
By:
Alexandre Moudrak, Andriy Konovaltsev, Johann Furthner, Jens Hammesfahr, Pascale Defraigne, Andreas Bauch, Stefan Bedrich, Arno Schroth
|
The offset between GPS and Galileo system timescales will cause a bias between GPS and Galileo measurements in combined
navigation equipment and lessen the accuracy of user position and time solutions.
GPS and Power Grid Intermesh
Nov 1, 2003
By:
Paul Stergiou, David Kalokitis
|
Engineers rebuilding lower Manhattan's power supply grid after 9/11 devised a GPS-clocked intermesh solution to bring new substations online. The process measured power sine waves, and developed software to link GPS to the electrical distribution system ? shortening a 72-hour operation to four hours, without service interruption. The method accurately measures any two low-frequency sine waves and compares them remotely for phase-angle displacement and voltage magnitude difference in real time.
Europe's proposed Galileo system has become the focus of mounting political pressures from inside and outside the European Union.
