North Atlantic Radio System
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The North Atlantic Radio System (NARS) was a chain of five tropospheric scatter communication sites that stretched from Iceland to RAF Fylingdales, forming an extension of the Distant Early Warning Line (DEW Line).
Built for the United States Air Force (USAF) during the early 1960s by Western Electric (AT&T), the sites were maintained under contract by ITT Federal Electric Corporation (now ITT Federal Services Corp.). The NARS network relayed Air-Defence radar data from co-located radars at each site, sending and receiving data via large fixed billboard style antennae, which bounced their signals off the bottom of the Troposphere, hence tropospheric scatter.
Although not a part of the (DEW Line), the NARS connected with the North American network at the common DYE-5/NARS 41 Site in Iceland. It also provided connectivity for the Ballistic Missile Early Warning System (BMEWS) site at RAF Fylingdales.
From 1960 the troposcatter sites were built as:-
- Site 41 – Keflavik, Iceland
- Co-located with DYE-5. Technically, western half of site was DYE-5, eastern half was NARS 41. Connecting with co-located USAF radar site H-1 at Rockville AS.
- Site 42 – Höfn, Iceland
- Connecting with co-located USAF radar H-3 at Hofn AS.
- Site 43 – Tórshavn, Faroe Islands
- Connecting a co-located Royal Danish Air Force radar.
- Site 44 – RAF Mormond Hill
- Near Fraserburgh, connecting the radar at RAF Buchan, co-located with an ACE High troposcatter station as well as LOS microwave links.
- Site 46 – RAF Fylingdales
- Connecting the BMEWS radar.
The NARS used AN/FRC-39A(V) transmitting and receiving equipment, manufactured by Radio Engineering Laboratories, which could be configured for 1 kW, 10 kW or 50 kW power output depending on the range and/or quality of signal required. NARS sites were configured for 10 kW output, with the exception of site 41 in both directions and site 42's connection to site 41. Each set consisted of two transmitters and four receivers, for redundancy and to boost signal to noise ratios, using vacuum tube technology which proved time consuming to maintain at high levels of efficiency. Levels of service proved extremely variable with the effects of weather and finicky equipment frequently causing loss of connection. Improvements were gained through improved maintenance procedures but did not change significantly until the introduction of solid state technology, with the system able to transmit at 9.6kbit/s, (a very fast internet connection for that time), by the time the system was closed down in 1992 after 30 years of service. With the advent of satellite communications the days of the Troposcatter networks were over, but NARS was closed down early due to the loss of the DYE-2 DEW Line station in 1988, severing the networks connection with the rest of the DEW line. Site 46 also had to close to make way for the new BMEWS Phased Array Radar at RAF Fylingdales.
- Radio propagation
- ACE High - Cold war era NATO European troposcatter network
- White Alice Communications System - Cold war era Alaskan tropospheric communications link
- List of White Alice Communications System sites
- TV-FM DX
- List of DEW Line Sites
- Distant Early Warning Line