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Patent of the Month: May 2020


Image of May 2020's Patent of the month title

Technology Description

Disciplined clocks work by using an external reference source to synchronize the time of their local clock, and to control the frequency of the clock’s local oscillator so that the clock is continuously kept on time.  The external reference source for a disciplined clock is typically a radio frequency (RF) signal that originates from a global navigation satellite system (GNSS), such as the U.S. Global Positioning System (GPS), the Russian Global Navigation Satellite System, or the European Galileo system.  Each GNSS system is referenced to a specific time scale that does not meet the legal and/or technical requirements of all applications. This problem is solved by the invention of the multi-source, common-view disciplined clock (MSCVDC) with fail-safe redundancy.


Line drawing of the disciplined clock system
This is a disciplined clock system that includes common view clock 102 to provide common view signal 108, disciplined clock 100 in communication with common view clock 102 to receive common view signal 108 from common view clock 102, reference clock 104 to receive common view signal 110 from common view clock 102 and to communicate reference signal 116, and remote timing analyzer 106 in communication with reference clock 104 to receive reference signal 116 from reference clock 104. Remote timing analyzer 106 produces analyzer signal 114 based on reference signal 116 and communicates analyzer signal 114 to disciplined clock 100. Reference signal 116 can include reference time difference RTD, and analyzer signal 114 can include reference time difference RTD, remote time difference RemTD, and the like, or a combination of the RTD and RemTD. In this manner, disciplined clock 100 can produce disciplined frequency 30 or disciplined time 32 based on reference time difference RTD or remote time difference RemTD.



Michael A. Lombardi
michael.lombardi [at] (michael[dot]lombardi[at]nist[dot]gov)

Technology Type

Advanced Networking, Computer Security, Cyber Security, Cyber Security/Information Assurance, Digital Information Access, Electronics, Information Technology, Intelligent Systems, Precision Measurement, Time and Frequency, Time and Frequency Services


More versatile than a GNSS disciplined clock because it allows the user to select the time scale that is used to discipline the clock.

Provides fail-safe layers of redundancy that a GNSS disciplined clock does not provide.  For example, if the network link to common-view data is unavailable, the clock can automatically switch to time obtained through GNSS satellites to provide holdover until the network connection is restored.

If the reference time scale is unavailable, the clock can automatically switch to another time scale simply by accessing common-view data from that time scale.

The MSCVDC can operate completely independent of GNSS if a non-GNSS source, such as a terrestrial radio station,  geostationary satellite, or network time source, provides the common-view signal.  This can eliminate concerns of dependency on GNSS time.

Click here for a printable description of the patent of the month.


Licensing Inquiries may be sent to TPO [at] NIST.GOV


A picture of a powerpoint slide describing Michael Lombardi's Patent number 10,466,363 B2
Created April 27, 2020, Updated August 23, 2023