Modernized LORAN-C timing test bed status and results

Abstract

LORAN-C is being examined as a viable backup to GPS for timing and navigation. Accuracy from the LORAN-C network has always been limited by variations in the propagation delay of the 100 kHz LORAN pulse. Using common-view techniques that are commonly used in GPS, LORAN data can be corrected to improve timing accuracy. The USCG plans to transmit corrections in real time via a new pulse in the LORAN signal called the LORAN data channel (LDC). Initial testing was conducted using a 3 monitor network of Timing Solutions Corporation (TSC) in Boulder CO, NIST in Boulder CO and LORAN Station Gillette WY. This provided a short baseline between TSC and NIST and a long baseline between TSC and Gillette. This setup showed that even in the long baseline, LORAN-C could be used as a precision (sub 50 ns RMS) time recovery system in the western US. Upon completion of the proof-of-concept test in Colorado and Wyoming, a second, more extensive experiment was initiated on the east coast where greater variations in propagation delay have been historically observed. Monitors have been configured at the LORAN Support Unit in Wildwood, NJ, the United States Naval Observatory in Washington D.C. and the Naval Research Laboratory in Washington D.C. These monitors collect data that will initially be post processed in a common-view LORAN solution between the different collection points. As the test progresses, corrections from some or all of these monitors will be transmitted via the LDC and processed in real time by the network of prototype receivers. This paper will present results to date on the east coast network and provide the schedule for the testing of real time corrections via the LDC