INSIDE GNSS NEWS just recently published an article featuring Satelles: “A new satellite-based positioning and timing system now available from partners Iridium and Satelles incorporates layered security elements into a service that offers 20- to 50-meter unaided position accuracy worldwide and could serve as a GNSS backup, according to the companies.

The Satelles Location and Timing (STL) service, also offers microsecond timing accuracy, said Satelles CEO Michael O’Connor — and that can be improved with more advanced receivers.

“Incorporating a higher quality clock in the user equipment results in higher performance,” O’Connor told Inside GNSS.  “We’ve even seen, in some cases, better than 100 ns timing accuracy with, for example, the rubidium oscillator.”

The reason for the range in position accuracy has to do with the data going into the navigation solution. Instead of using signals from three or four different satellites at once, the Satelles user equipment receives signals from the same low Earth orbit (LEO) spacecraft as it passes overhead.

“An Iridium satellite goes from horizon to horizon in less than eight minutes, and that does two things,” said Greg Gutt, the Herndon, Virginia–based company’s president and chief technology officer. “The first is that it provides a very strong Doppler signature, which can be used in the navigation solution. GPS receivers rely significantly less on Doppler because the satellites don’t move very quickly in a typical scenario. With the LEOs, the Doppler signature is quite strong — and that helps.”  Link to full article, credit:  Dee Ann Divis, Inside GNSS News, June 15, 2016