Featured Research

from universities, journals, and other organizations

NIST Method Improves Reliability Of GPS Clocks

Date:
October 12, 2005
Source:
National Institute of Standards and Technology
Summary:
A statistical method, developed by the National Institute of Standards and Technology (NIST) and tested and implemented with the help of several collaborators, has made the job of analyzing the accuracy and reliability of Global Positioning System time signals significantly faster and easier. The method will help ensure that GPS clocks produce accurate location and distance measurements and remain closely synchronized with official world time.

A U.S. Air Force staff sergeant acquires Global Positioning System coordinates.
Credit: Photo by S. A. Cuomo/U.S. Air Force

Widelyused by the military, first responders, surveyors and even consumers,GPS is a navigation and positioning system consisting of ground-basedmonitors and a constellation of satellites that rely on atomic clocks.A statistical method, developed by the National Institute of Standardsand Technology (NIST) and tested and implemented with the help ofseveral collaborators, has made the job of analyzing the accuracy andreliability of these satellite-borne time signals significantly fasterand easier. The method will help ensure that GPS clocks produceaccurate location and distance measurements and remain closelysynchronized with official world time.

The NIST method, describedin a recent paper,* has been incorporated over the past few years intothe GPS clock analysis software system managed by the Naval ResearchLaboratory (NRL). The satellite clocks—commercial devices based in parton research originally done at NIST—use the natural oscillations ofrubidium atoms as "ticks," or frequency standards. The algorithm helpsdetect and correct GPS time and frequency anomalies. The algorithm alsocan be used to improve the control of other types of atomic clocks andhas been incorporated into commercial software and instruments forvarious timing applications, according to NIST electronics engineerDavid Howe, lead author of the paper.

A GPS receiver pinpointsits location based on the distance to three or more GPS satellites atknown locations in space. The distance is calculated from the time ittakes for satellite radio signals to travel to the receiver. Thus,timing accuracy affects distance measurements. The NIST method makes aseries of mathematical calculations to account for numerous measures ofrandom "noise" fluctuations in clock operation simultaneously. Thismakes it easier to estimate many sources of error and identify theonset of instabilities in the clocks in minutes or hours rather thandays. Adjustments then can be made promptly. The technique also couldaccelerate the evaluation of clocks during the process of building GPSsatellites, where test time is at a premium. "Ultimately, it shouldimprove reliability, stability and accuracy for many people who use GPSfor time and navigation,"said Howe.

Co-authors of the paperinclude scientists from NRL, the Jet Propulsion Laboratory at theCalifornia Institute of Technology, the Observatoire de Besancon inFrance, and Hamilton Technical Services in South Carolina.

###

* D.A. Howe, R.L. Beard, C.A. Greenhall, F. Vernotte, W.J. Riley,T.K. Peppler. Enhancements to GPS operations and clock evaluationsusing a "total" hadamard deviation. IEEE Transactions on Ultrasonics,Ferroelectrics, and Frequency Control. August 2005.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology. Note: Materials may be edited for content and length.


Cite This Page:

National Institute of Standards and Technology. "NIST Method Improves Reliability Of GPS Clocks." ScienceDaily. ScienceDaily, 12 October 2005. <www.sciencedaily.com/releases/2005/10/051011074428.htm>.
National Institute of Standards and Technology. (2005, October 12). NIST Method Improves Reliability Of GPS Clocks. ScienceDaily. Retrieved July 26, 2014 from www.sciencedaily.com/releases/2005/10/051011074428.htm
National Institute of Standards and Technology. "NIST Method Improves Reliability Of GPS Clocks." ScienceDaily. www.sciencedaily.com/releases/2005/10/051011074428.htm (accessed July 26, 2014).

Share This




More Matter & Energy News

Saturday, July 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins