New Life for LORAN Part 1

摘要

It's not very often that a guy gets to witness "the changing of the guard" during his lifetime, but I've been fortunate enough to do just that. As the years have gone by, we've all seen technology change in unimaginable ways that stun us with "gee whiz" events. December 8, 2003 marked the beginning of the end in an era of vacuum tube LORAN "C" (LOng RAnge Navigation) transmitters. The last of the US Coast Guard's highest powered vacuum tube transmitters (AN/FPN-45) — 1.6 megawatts pulsed power output — was shut down on that date. In its place, a solidstate transmitter (Accufix Model 7500) at 1.3 megawatts was placed on air to continue the LORAN legacy at LORAN C Station George, WA. LORAN's history dates back more than six decades, with LORAN "A" sprinkled near coastlines around the world. It was the major wide area coverage navigational system before LORAN "C" was implemented, eventually replacing the "A" stations. LORAN A operated on 1750, 1850, 1900, and 1950 kHz. Amateur radio operators using 160 meters were restricted in frequency use and DC power input — daytime and nighttime — depending upon geographic location in the US and Canada. The restrictions were imposed because of anticipated interference to LORAN A signals. Gradually, LORAN C stations took over the navigation duties and forced the LORAN A stations into history. The last series of A stations were taken off the air from July 1979 to July 1980 in the CIS. Amateurs no longer suffer 160 meter restrictions.