October 20th Luncheon Meeting

Space-based PNT is great … until it isn’t.  Why Loran is here to stay

Charles “Chuck” Schue is the Founder and CEO of Ursa Navigation Solutions, Inc. (d/b/a “UrsaNav”)

A globally recognized expert in positioning, navigation, and timing (PNT) systems, his contributions have led to major critical infrastructure and safety-of-life system improvements in the United States and abroad. Chuck is also a founder/owner of several other advanced engineering firms, with products as diverse as in-space electric propulsion and pre-shot sniper detection.

Chuck holds three master’s degrees and is a Senior Member of the American Society for Quality and the Institute for Electrical and Electronics Engineers. He is a Fellow of both the Institute of Navigation and the Royal Institute of Navigation.

The history of Long-Range Radionavigation (LORAN, n/k/a Loran) has always been tightly  coupled with military operations. The mission critical need for radionavigation systems was driven  by military necessity and by a need to provide a competitive advantage over adversaries. Aviation requirements were the dominant factor during the early history of the development of radionavigation systems prior to and during WWII. Various systems were developed, tested, and  deployed during this time, including Gee, LRN, CYCLAN, and various versions of Loran (e.g.,  Loran-A, Loran-B). These systems, and others, were all part of the family tree of what eventually became Loran-C, which was first deployed by the US Navy in 1957. 

While most early uses of Loran were for military operations, Loran-C evolved into a Positioning, Navigation, and Timing (PNT) solution widely used for civilian and military applications. These uses included timing and frequency for telecommunication systems and other terrestrial command and control systems, maritime navigation, messaging, and aviation use in military and general  aviation aircraft. The widespread use of Loran-C during Operation Desert Storm was the  culmination of these developments. 

The parallels with the evolution of GPS are clear and historically interesting, but eventually the widespread availability of GPS signals, the elimination of Selective Availability, and the significant reduction in the cost of GPS receiver equipment because of mass market effects led many to believe that no other PNT source was required. After significant debate, much of the world’s Loran-C infrastructure was closed and removed or mothballed. Over time, many users of PNT services became aware of the vulnerabilities of satellite-based signals. These inherently weak  signals from space are easy to jam and the signals have been shown to be vulnerable to spoofing.  At the same time, GPS has become ubiquitous in both military and civilian applications. As the  most easily accessible source of PNT, GPS signals have become a significant target of adversaries.  Perhaps we were a little hasty in our zeal to eliminate alternative PNT solutions. 

This presentation will focus on the evolution of Loran-C from its roots, through various  modernizations, and then to what is now called Enhanced Loran (eLoran). Then we will explore how eLoran can provide the PNT resilience required to protect National Critical Infrastructure  and Key Resource Sectors. We will discuss options and applications for uses of eLoran for aviation, location-based, land-mobile, maritime, and timing and frequency users. 

Other advances in eLoran will also be discussed, such as mixed-use or “private” eLoran. Most previously deployed Loran systems used open signals that were available to any user with a Loran receiver. Some systems also included the ability to send secure messages. Private eLoran might  include limiting some portion of the signal and/or the data channels to authorized users, such as is done with modern GPS.