GNSS Accuracy and Resiliency Improvements Using Real-Time Common View Time Transfer

Multi-band (dual-band) GNSS receiver is essential for meeting PRTC-B (or tighter) requirements. In case of accidental or intentional jamming of one of the two frequencies (note that L1 jamming is much more common), dual-band GNSS receivers would no longer be able to meet the PRTC-B requirements (see picture below).

One of the findings of STRIKE3 project, which was focused on monitoring of GNSS interference across different sites, was that there is an upward trend in the number of reported interference events throughout the course of the campaign. Note that with proliferation of personal GNSS devices we could expect proliferation of personal jamming devices. Therefore it is important that GNSS based timing devices, which would be installed near locations with higher density of jamming incidents (major roads, and highways, etc.) are equipped with jamming mitigation methods.

Our innovative approach, which relies on distribution of GNSS measurements from a reference site to clients, helps client GNSS receivers to maintain PRTC-B or better performance throughout single band jamming incidents. Note that single band jamming incidents on L1 frequency are six times more likely than jamming on other GNSS frequencies (L2, or L5), for details on that see here.

Timing Solutions has developed a Real-Time Common View Time Transfer technique that has the following advantages:

  • Receiver independent solution;
  • Maintain at least PRTC-B performance throughout jamming incidents;
  • Improve single band receiver performance to meet at least PRTC-B;
  • Improve Resiliency by using authenticated data approach for any constellation and any receiver;
  • Remove most GNSS data related threats/issues (UTC parameters, satellite clock corrections, frequency dependent effects, etc.). RTCVTT would NOT be affected by GPS’ January 2016 anomaly, nor Galileo’s week-long outage;
  • A very powerful GNSS threats detector: simulators & data replays;
  • Cost effective enabler of coherent network PRTC (cnPRTC) architecture;
  • No monthly fees, no external data required, everything internalised within customer’s private network.

Real Time Common View Time Transfer solution is based on a Server – Client architecture, much like PTP. Data needs to be sent every minute or so. It is possible to improve performance of clients over a very large distance ~1000 km.

Our solution was verified at NSAI NML at Dublin, Ireland.