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This paper describes a common-view disciplined oscillator (CVDO) that locks to a reference time scale through the use of common-view global positioning system (GPS) satellite measurements. The CVDO employs a proportional-integral-derivative controller that obtains near real-time common-view GPS measurements from the internet and provides steering(More)
B efore the invention of atomic clocks, the second was defined by dividing the period of an astronomical event into a shorter time interval. For example, the second was once defined by dividing the average period of one revolution of the Earth on its axis. The mean solar second was equal to 1/86,400 of the mean solar day. To create a more stable unit of(More)
1 1.. I In nt tr ro od du uc ct ti io on n There is a small but growing demand for calibration laboratories and research facilities to maintain a high accuracy time standard. This requires the laboratory to continuously generate a 1 pulse per second (pps) on-time signal, and for laboratories in the United States, to be able to state the uncertainty of that(More)
The Sistema Interamericano de Metrologia (SIM) is a regional metrology organization (RMO) whose members are the national metrology institutes (NMIs) located in the 34 nations of the Organization of American States (OAS). The SIM/OAS region extends throughout North, Central, and South America and the Caribbean Islands. About half of the SIM NMIs maintain(More)
The timing pulse from a Global Positioning System (GPS) receiver is typically within 1µs of Coordinated Universal Time (UTC) kept at NIST, called UTC(NIST), even if the receiver and antenna have not been calibrated for delays. However, it is not possible for most laboratories to make an accurate measurement of their GPS receiver's time offset with respect(More)
NIST ended its Geostationary Operational Environmental Satellites (GOES) time code service at 0 hours, 0 minutes Coordinated Universal Time (UTC) on January 1, 2005. To commemorate the end of this historically significant service, this article provides a retrospective look at the GOES service and the important role it played in the history of satellite(More)