Friday, March 02, 2007

The First Radio Beacon

A radio beacon is non-directional transmitter that usually transmits a constant signal on a licensed radio frequency. Before the days of VOR, GPS, LORAN, beacons were used with direction finding equipment to find ones relative bearing to a known location. The beacon being the known location.

There are a few different kinds of radio beacons. There are amateur radio beacons that are used to test propagation of radio signals. At sea, there are marine beacons, though largely phased out. In aviation they use a beacon called Non-directional Beacon (NDB). These are used to help find airports.

In 1921 the first non-directional radio beacon (N.D.B.) went into service. It was operated by the Bureau of Lighthouses to assist marine navigation. A manual radio direction finder that was light enough for airborne use was developed in 1934 for these very NDBs. They were the core of navigational technology for decades.

By June 30, 1955, there were 173 NDBs operating in the United States. Since then a variety of much more dependable and accurate systems have been developed. The current plan is to decommission these beacons over the next few years as they are replaced with newer supposedly better technology. But at least today NDBs still pepper the landscape. These that still remain in service are kept as an emergency backup system in the case that these more "sophisticated" modern systems fail. Old obsolete technology is always more sturdy somehow...