Editing Time and frequency transfer (section)

==Common view==
The time difference between two clocks may be determined by simultaneously comparing each clock to a common reference signal that may be received at both sites.<ref>{{Citation |first1=David W. |last1=Allan |first2=Marc A. |last2=Weiss |title=Accurate Time and Frequency Transfer During Common-View of a GPS Satellite |journal=Proceedings of the 34th Annual Frequency Control Symposium USAERADCOM |place=Ft. Monmouth, NJ |date=May 1980 |pages=334–346 |doi=10.1109/FREQ.1980.200424 |url=http://www.boulder.nist.gov/timefreq/general/pdf/192.pdf}}</ref>  As long as both end stations receive the same satellite signal at the same time, the accuracy of the signal source is not important.  The nature of the received signal is not important, although widely available timing and navigation systems such as GPS or LORAN are convenient.

The accuracy of time transferred in this way is typically 1–10&nbsp;ns.<ref>{{Citation |url=http://tf.nist.gov/time/commonviewgps.htm |title=Common View GPS Time Transfer |author=Marc Weiss |publisher=NIST Time and Frequency Division |access-date=2011-11-22 |url-status=dead |archive-url=https://web.archive.org/web/20121028043917/http://tf.nist.gov/time/commonviewgps.htm |archive-date=2012-10-28 }}</ref>