Alpha (navigation)

Lore & Background

Alpha was developed in parallel with the U.S. Omega navigational system and operates in the VLF range. Its three active transmitters are located near Novosibirsk, Krasnodar, and Khabarovsk, while two others at Revda and Seyda were not operational as of 2010. The system radiates signals of 0.4 second duration in a 3.6 second cycle on three primary frequencies, with additional alternative frequencies available. A radio fix is obtained by measuring the phase difference of received signals.

Reader's Guide

Alpha (RSDN-20) represents a significant Russian contribution to long-range radio navigation, developed during the Cold War era alongside its Western counterpart, Omega. Its ability to provide positioning for aircraft, ships, and even submerged submarines made it a strategic asset. The system's reliance on VLF signals allowed for propagation over vast distances, up to 10,000 km, though with a relatively large position error of several kilometers. The gradual deactivation of transmitters beginning in 2014 and the continued operation of some as of 2017 reflect the system's declining role in an era of satellite-based navigation. Its legacy is tied to the broader history of terrestrial radio navigation systems like LORAN and CHAYKA, which have been largely superseded by GPS and GLONASS.

Did You Know?

• Alpha is also known as RSDN-20, with RSDN standing for 'radio-technical long-distance navigation system' in Russian.
• The system was developed in parallel with the U.S. Omega navigational system.
• Alpha's coverage extends up to 10,000 km from the master station, with a position error of 2.5 to 7 km.
• Two transmitters at Revda and Seyda were not operational as of 2010.