RSDN-20 (Alpha)
Identification
The supplied point matches the published position of the Revda transmitter of Russia’s ALFA/RSDN-20 long-range radionavigation network on the Kola Peninsula. Open technical sources place the Revda site at 68°02′07.8″N, 34°41′00.0″E, essentially the same location as the provided placemark, and a 2021 peer-reviewed review lists Revda as ALFA site MR. ([udxf.nl](https://www.udxf.nl/ELF-VLF-GUIDE-v1.0.pdf))
Network role
RSDN-20, known in Western literature as ALFA, is a Russian very-low-frequency long-range radionavigation system analogous to the former Omega system. ITU reporting in 2010 described ALFA as operating in the 10–17 kHz band with registered frequencies 11.905, 12.500, 12.649, 13.281, 14.881, and 15.625 kHz, using 3.6-second signal sequences and having a nominal operational range of about 10,000 km. ([itu.int](https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-RS.2186-2010-PDF-E.pdf))
Site layout
Open technical literature treats Revda as a transmitter field outside the named settlement rather than an urban facility. The 2021 review states ALFA sites use large antenna fields away from population centers and describes the network’s sites as seven-mast arrays in a hexagon-plus-center pattern; it places the Revda field about 120 km from Murmansk, while a 2025 VLF guide explicitly places the field on the Kola Peninsula. ([transnav.eu](https://www.transnav.eu/files/The_Russian_ALFA_System_in_the_Context_of_the_Development_of_Radionavigation_in_the_21st_Century%2C1166.pdf))
Status
Revda’s current operating status is not firmly confirmed in open sources. A 2021 peer-reviewed review, citing archived Russian Institute of Radionavigation and Time material, says the Revda station had been switched off and that by 2017 only Novosibirsk, Krasnodar, and Khabarovsk were operational; a 2025 specialist VLF guide likewise marks Revda as not active and presumed shut down. ([transnav.eu](https://www.transnav.eu/files/The_Russian_ALFA_System_in_the_Context_of_the_Development_of_Radionavigation_in_the_21st_Century%2C1166.pdf))
Arctic relevance
A 2025 scientific paper analyzing 2021 propagation data measured RSDN-20 signals from Khabarovsk, Novosibirsk, and Krasnodar, which is consistent with the three-transmitter active picture and provides no direct evidence that Revda was radiating in that period. The 2021 review nevertheless assessed the network’s northern geometry as oriented toward Arctic waters, which explains the geographic importance of a Revda/Kola site within the ALFA architecture if returned to service. ([zh-szf.ru](https://zh-szf.ru/temp/970df847c981fba6959da01e982d0518.pdf))