Those interested in GNSS and the law (what country's?) might like to see this article entitled: "Reliable time from GNSS signals" from the March/April 2017 Inside GNSS magazine, page 38. As far as I can determine, the URL is: http://online.qmags.com/GNSS0317#pg39&mode2 It was less technical than I had hoped from the title, being somewhat more about traceability than reliability, but I suppose it depends on your point of view! Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-taylor@blueyonder.co.uk Twitter: @gm8arv