EDWARDS AIR FORCE BASE, Calif -- An Air Force Flight Test Center aircrew flew a C-141A on a nonstop 15-hour from Edwards Air Force Base, California, to the United States East Coast and back. The sortie, covering 6,535 miles, was conducted to evaluate the APN-151 Loran C radio navigation system.
The term LORAN is an acronym derived from the words LOng RAnge Navigation. The original design concept has been extended to meet increasing requirements for accuracy, resulting in the development of three successive systems designated LORAN-A, LORAN-C, and LORAN-D. LORAN-C and LORAN-D have matured to provide accurate and reliable positioning information. With the development of fully automatic receivers for LORAN-C and LORAN-D, system characteristics have become hidden to the general user of LORAN. This has contributed to a general lack of understanding of LORAN and its capabilities. This report is an overview of the LORAN system and LORAN receiver signal processing. The material is organized in three levels of technical complexity: First, a basic discussion of system characteristics to familiarize the reader with LORAN; second, a more detailed description of the LORAN signal; finally, a review of signal processing in LORAN receiving systems.