The US Coast Guard (USCG) NAVIGATION CENTER .
Peter Dana at the Univ. of Texas and Navtech are other sources of GPS links.
Tony Fisher has made some co-ordinate transformation software available.
GPS NAVIGATION :
The US Coast Guard (USCG) NAVIGATION CENTER .
Peter Dana at the Univ. of Texas and Navtech are other sources of GPS links.
TIME AND FREQUENCY :
The IEEE UFFU Ultrasonics, Ferroelectrics and Frequency Control Society
The US Naval Observatory Directorate of Time is all about time standards and services including time from navaids.
In the UK the National Physical Laboratory is responsible for the UK time standard.
In the USA NIST (ex NBS) is responsible for the US time standard, there is also a live clock.
Gordon Uber has a lot of clock, time and frequency information.
Professor David L. Mills has also provided information on time transfer and other related topics.