Thursday, June 02, 2005

The FRD-10: An endangered species

FRD-10 array

In the early 1960s the U.S. Naval Security Group began deploying a network of large high-frequency direction-finding (HF-DF) circularly disposed antenna arrays, the AN/FRD-10s, to detect, monitor, and plot the location of Soviet submarines and other radio emitters in the Atlantic and Pacific oceans.

Sometimes dubbed Elephant Cages or Dinosaur Cages, the FRD-10 arrays were enormous structures. In the centre of each array was a two-storey operations building, about 40 metres square, where the station personnel worked. Surrounding this building were two concentric rings of HF antennas, one for shorter HF wavelengths, containing 120 sleeve monopoles, and one for longer HF wavelengths, containing 40 folded dipoles. The shorter wavelength ring was about 260 metres in diameter and the longer wavelength ring was about 230 metres in diameter. Inside each ring there was also a large wire screen, supported by 80 towers, which was designed to prevent HF signals from crossing the array and interfering with its operations. The inner screen, corresponding to the longer HF wavelengths, was roughly 36 metres high. A horizontal ground screen about 390 metres in diameter surrounded the entire site. (Aerial views of an FRD-10 array here.)

Fourteen of the huge arrays were eventually deployed by the NSG (not counting two built at Sugar Grove, WV, for communications rather than intelligence-gathering):
  • Adak, Alaska
  • Edzell, Scotland
  • Galeta Island, Panama
  • Guam
  • Hanza, Okinawa
  • Homestead, Florida
  • Imperial Beach, California
  • Marietta, Washington
  • Northwest, Virginia
  • Rota, Spain
  • Sebana Seca, Puerto Rico
  • Skaggs Island, California
  • Wahiawa, Hawaii
  • Winter Harbor, Maine
Another two were built by the Canadian Forces Supplementary Radio System: one at Gander, Newfoundland and one at Masset, British Columbia (both built in 1970-71).

The FRD-10 arrays became the backbone of the BULLSEYE net, the Atlantic and Pacific HF-DF nets. They were supplemented by a number of smaller, simpler CDAAs known as Pushers, including a Canadian Pusher in Bermuda. (Canada also has Pushers deployed at Leitrim and Alert.)

The FRD-10s offered four major improvements over their predecessors, the GRD-6 in NSG service and the GRD-501 in Canadian service:
  1. transmissions could be recorded for immediate or subsequent DF-ing;
  2. bearings were four times as accurate;
  3. antenna gain was about four times higher than previous systems; and
  4. the system had the ability to select wanted signals and reject interfering signals or noise.
As noted in the Supplementary Radio Activities Consolidation Plan (30 May 1966), the improvement expected as a result of deploying the FRD-10s was "a combination of more accurate and reliable fixes, producing reduced search areas in ocean areas of prime responsibility so fresh in time as to enable maritime commanders to deploy their forces more economically and with much greater prospect of making contact with the target than is now the case."

The following maps show the locations of FRD-10 (black circles with pink dots) and Pusher arrays (empty black circles) during the system's heyday.

Atlantic HF-DF stations
Click to see full-sized image


Pacific HF-DF stations
Click to see full-sized image


In the mid-1990s, however, the NSG began to close down its FRD-10 arrays. The demise of their Soviet targets, a desire to refocus collection efforts and cut costs, and, presumably, a decision to rely on alternative ocean surveillance technologies has led to the near-extinction of the FRD-10. Canada's two arrays are the only ones left in service. Most of the others have already been dismantled. (Al Grobmeier has written more on the fate of the NSG FRD-10s.)

The Canadian FRD-10s themselves were converted in 1997 so they could be remotely operated from CFS Leitrim. Presumably they are primarily used for HF intercept operations now, although DF would remain as a residual capability. The Masset and Gander arrays no longer have other FRD-10s to work with, but they can still work with the Canadian Pusher arrays at Leitrim and Alert, and possibly with other arrays still operated by UKUSA allies.

The first step in this direction may have been Project Polo (G1777), which was established in the late 1980s to "modernise the CFSRS High Frequency/Direction Finding (HF/DF) system at CFS Masset and Gander, and to equip CFS Alert for netted DF Operations."

Did Canada see the demise of the FRD-10 network coming? It seems unlikely that the authors of Challenge and Commitment, the 1987 Defence White Paper (précis: "The Soviet Threat will go on forever"), expected the UKUSA allies' main ocean surveillance networks to be shut down within a decade, so assuming the two sites remain useful and we're not just stuck with a couple of White Elephant Cages, maybe we got lucky.

[Update 25 August 2005: Corrected to include the FRD-10 built at Marietta, Washington, and update info on the fate of the NSG FRD-10s. The FRD-10 at Marietta was dismantled in 1972, possibly as a result of the Masset array's entry into service.]

[Update 14 December 2007: As noted in the comments, the NSG detachments at US Army/Air Force FLR-9 CDAA sites also participated in the BULLSEYE net, as did some older NSG sites that continued operating the GRD-6 system (and older Canadian sites operating the GRD-501 system) for a number of years.]

[Update 24 June 2009: Information on the roughly equivalent Soviet Krug HF-DF network here.]

22 Comments:

Anonymous Anonymous said...

Check out cage at Elmendorf (Anchorage)

Not on your list

December 13, 2005 2:38 am  
Blogger Bill Robinson said...

Thanks for the feedback!

The Elmendorf "elephant cage" is an FLR-9, part of an Army/Air Force network that was separate from the FRD-10s of the BULLSEYE net. You can see the full list of FLR-9 sites here.

December 13, 2005 11:34 pm  
Anonymous Anonymous said...

Thanks for all the info.
My name is Peter Lewis. I was stationed at some of the sites. My father, Edward J. Lewis Jr. was involved in the location and construction of these sites. He was a CTCM and served 31 years in the Navy. He also taught code in Imperial Beach. It is gratifying to see what a challenge he had to face in the work he did.
Thanks again.
My email is: pclewisover50@hotmail.com

April 04, 2006 9:33 am  
Anonymous Bill said...

You did not include some of the USAF sites. One of which was San Vito, IT. Also, Clark AFB, PI.

May 02, 2007 6:38 pm  
Anonymous Anonymous said...

In 1975 to 77 I was ststioned in my home town of Homestead, Florida. At that time I was amused that we had Canadian Forces stationed there also and they were on Foriegn Duty. Never thought the US was foriegn duty till then.

May 02, 2007 7:14 pm  
Anonymous Anonymous said...

I was an HDFD instructor and "taught" many a Canadian (or in some cases they taught me). Also served a stint at Gander (I miss the Screech!!). You guys were/are a bunch of pro's and I value my time served with you.

May 02, 2007 7:59 pm  
Blogger Bill Robinson said...

Hi, all. Thanks for the recent comments. This is not a high traffic blog, so the 400 or so visits in the last 24 hours equal about a month's worth of normal traffic around here. I'm assuming that somebody sent a notice about the FRD-10 posting to some massive NSG retirees list. I deliberately left the FLR-9 sites off my list, but I guess the NSG dets at those sites did participate in the BULLSEYE net so I really should mention them. Did all the FLR-9s participate?

May 03, 2007 5:10 pm  
Anonymous Anonymous said...

Check out Sidi Yahia, Morocco for an FRD-10 site.

May 04, 2007 11:05 am  
Anonymous Anonymous said...

I was stationed at the Hanza Okinawa Japan CDAA for about 3 years in the mid to late 60's. The physical facilities are still there, including the antennas. This CDAA facility is clearly visible using Google Earth images. I'm not sure what the date of the image is,but within the last few months the image resolution in the area was increased significantly. So if it has since been removed, it has been only in the last few months.

I'm ptetty sure that Naval Security Group is no longer using the site. for its originally intended purpose.

May 06, 2007 1:23 am  
Anonymous Steve Atwell - USMC said...

Interesting info on your web site. I worked in the FRD10 in the swamp at NSGA Homestead from 1981 to 1984. What a great mission and a great time to be in Florida (no hurricanes). It would be great to find some of the Canadians I worked with in Florida. Very sharp troops.

May 22, 2007 10:00 pm  
Blogger Bill Robinson said...

Hi, Steve.

Thanks for the comment. Check out Online Oldtimers and 291 Happenings for lots of contact information for current and former 291ers.

May 22, 2007 10:38 pm  
Anonymous Anonymous said...

Hi,

The new HBO series, John from Cincinnati has the Imperial Beach station in the show. I had no idea what the character was looking at until an IMDB post directed me to your site. I'm now much more enlightened.

Thanks

Kleinzeit & Archie

July 06, 2007 11:58 am  
Blogger bombadil said...

A few months ago I went to Google earth and looked up the old array at Clark AB in the Philippines and it appeared that someone had turned the thing into something that looks like a pavilion.

September 10, 2007 1:09 pm  
Anonymous Anonymous said...

Bill,

You asked if all the FLR-9 sites participated in the network. I can tell you that Elmendorf did. There were also still some sites participating using the old GRD-6 arrays also (Iceland).

November 11, 2007 8:11 pm  
Anonymous Anonymous said...

Also, in the early 70's the Navy was deploying a flr-15, haven't heard much of what happened to them

March 30, 2008 4:43 pm  
Anonymous Anonymous said...

Bill:
Just 'stumbled' on your blog...
'Velly Intellesting...'
I did about 60-75 TDY's to Gander from 1975 to 1999, plus visits to all the other CFSRS sites(less Alert!).
I retired from the 'business' in 2000.
Overall info in your Blog + comments about 90-95 % accurate, Well Done!

"Long may your big jib draw"

Dennis Skiffington

August 17, 2008 3:27 pm  
Anonymous Craig Reed said...

My father helped invent and deploy the BULLSEYE network in the 1960s. As a former submariner turned writer, I'm writing a book about submarine programs that includes this technology. I'm interested in talking with anyone involved with these systems during the cold war. Please contact me at wc@reedwriting.com.

November 07, 2008 1:33 pm  
Blogger Bob said...

Bill,
Thanks for web page, took me back to when I was in SecGru 61 - 69. Worked on FRD-10 on Guam, Edzell and communicated with Chicksands when working on Audley St. London(66-69). Hope maybe one day to see full storey about FRD's. Thanks again and Well Done.

Bob H.

September 30, 2009 11:12 am  
Anonymous Anonymous said...

As a ham radio operator I found your site about the HFDF antennas interesting. I also am interested in what is now being called COLD WAR relics!

Thanks,
Mike KD4LLA

January 23, 2010 3:46 pm  
Anonymous Anonymous said...

Has anyone noticed lately that there are a lot of vehicles parked around the ops building at the Imperial Beach FRD-10A? I'd swear the thing was in operation.

32°35'39.02"N
117° 7'48.16"W

March 10, 2011 10:24 pm  
Anonymous Mike P said...

I worked with the Pongo's at both CFS Massett and CFS Gander back in the 70s and early 80s. Good duty, boy, could the guys at Massett put away the Labatt's!

December 31, 2011 4:57 pm  
Anonymous m2jranch@yahoo.com said...

'Anonymous' mentioned Iceland; assume
he was referring to the Keflavik NSG
sites at Hafnir and 'Rockville'. The
Hafnir and mainbase (NSG comms relay)
sites were closed in 1978 and conso-
lidated into a new building at Rock-
ville with a 'Pusher'. That site has
been closed now for a number of years
unless USAF (or civilians) are using
it. 'Bob H' mentioned his time at
7 N Audlry in 66-68 time frame. Were you on 7th deck or at 2 PC? I
was there 1/65-12/67 at both loca-
tions (watched 'em build 2PC. Jim

August 22, 2012 3:19 am  

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