Tracking Cold War Signals

Adcock four element antenna array
WWII Naval direction finding station
(source: Frontline Ulster)

The Cold War was also a war of signals. This battle comprised chatter over radio, Morse, data and technical signals. Eavesdropping on enemy communications and analyzing their technical signals was a vital part of that battle. However, to know where those signals came from was just as important.

Directional antennas find the bearing of a signal. Early simple loop antennas had to be turned mechanically to find the signal bearing. With two or more such antennas on different locations, the target is located at the crossing of those bearings, but it was a cumbersome task. Later, double loop antennas and Adcock antenna arrays with four elements improved performance, but many more special  direction finding (DF) antennas were built to locate signals, and some were quite extraordinary.

German Wartime Research

The Wullenweber antenna array
(source: FGCRT)

Significant progress was made during the Second World War by Dr. Hans Rindfleisch, who invented the Circularly Disposed Antenna Array (CDAA). Rindfleisch also headed the Communications Research Command of the German Navy, and together with Telefunken they developed his antenna array under the codename Wullenweber.

The first Wullenweber, build in Skibsby in northern Denmark, was designed as high-frequency direction finding (HF/DF) antenna array and operated in the 6-20 MHz range. The above drawing shows, at the top, the view of the antenna array and the reflector screen wires behind them (click image to enlarge)

 

First Wullenweber at Skibsby site
(source unknown)

The antenna consisted of 40 vertical radiator elements, each supported by a wooden structure and placed in a large circle, 120 m (392 ft) in diameter. Inside that circle was a reflector screen of wires, supported by 40 poles and arranged in a smaller circle, 105 m (344 ft) in diameter.

The Foundation for German communication and related technologies (main page) has a description of the Wullenwever (original spelling), including German Naval research on Wullenwever (pdf p11-20) and the Landsberg-Lech conference (pdf) with technical details and several photos of  the Skibsby Wullenweber site.

German Technology in Soviet Hands

Many German scientists were rounded up by US and Soviet forces in the final days of the war. Both were interested in this new CDAA technology, but the Soviets were the first to start building them in 1951 with assistance of German scientists.

The Soviets eventually build 31 CDAA's of various types and called them KRUG. They were placed in Russia, Warsaw Pact countries, Mongolia, Cuba, Vietnam and Burma. These KRUG stations tracked radio communications of US and NATO reconnaissance aircraft and nuclear bombers. GlobalSecurity has info and photos on Soviet KRUG antenna arrays.

The Global U.S. Antenna Network

One of the German antenna researchers was moved to the United States to assists in the development of a CDAA. The US version of the Wullenweber was the AN/FLR-9 antenna, nicknamed "Elephant Cage". The first was built in 1962 at the RAF Chicksands base in the UK, leased by the US Air Force.

FLR-9 at USASA Field Station Augsburg, Germany (source: US Air Force ISR)

The huge FLR-9 antenna had an outer diameter of 440 m (1,443 ft) and height 37 m (121 ft). A network of eight FLR-9 was constructed in Alaska, England, Germany, Italy, Japan, Philippines, Turkey and Thailand. This network could accurately locate HF signals anywhere on Earth, to track enemy airplanes, ships or ground based transmitters, but also to follow own or friendly targets.

The US Naval Security Group operated the AN/FRD-10, also a Wullenweber antenna but smaller than the FLR-9. Its outer diameter was 263 m (863 ft). A network of sixteen FRD-10's was located at coastal lines of the Pacific and Atlantic on US mainland and Alaska, Hawai, Puerto Rico, Canada,  Panama, Japan, Spain and Scotland.

More about the Wullenweber

FLR stands for Fixed Countermeasures Receiving. FRD stands for Fixed Radio Direction-finder (see JETDS designations). More about the FLR-9 on FAS and Freedom Through Vigilance Association (USAFSS). Navy Radio has details of the AN/FRD-10. There's a report on the dismantling of the AN/FLR-9 at Misawa air base in Japan and the decommissioning of Joint Base Elmendorf-Richardson in Alaska (video). See also locations of AN/FLR-9 antenna system at the Station Hypo website.

More on WWII direction finding at the RSS Secret Listeners website and on Frontline Ulster's WWII Aircraft Direction Finding in the UK.

The NSA video below explains the history and purpose of the FLR-9.

The Last Elephant Cage

 
The American Forces Network Pacific gave a look inside Misawa’s FLR-9, build in 1962. The antenna was demolished in 2014.

FLR-9 AFN Misawa

More on Signals

Many different signals were sent, received and analyzed during the Cold War. Below some posts on this blog about Signals Intelligence (SIGINT), but there's much more to discover...

• Mysterious Cold War signals Fascinating signals revealed
• Field Station Berlin ASA/NSA listening post
• Russia’s Modern Early Warning Systems
  
• Electronic Intelligence at NSA History of  ELINT
• More posts about signals intelligence...

Visit also the Cold War Signals page about the battle over radio waves on our website

Le Carré's Legacy for Spies

David Cornwell - John Le Carré
Source: Krimidoedel

David Cornwell passed away last December. He was not only a brilliant writer, but also someone who once in a while kicked the conscience of the establishment. John Le Carré was the alter ego of David Cornwell, who wrote his first three novels while still working for MI5 and MI6, from 1959 to 1964.

Le Carré is renowned for spy novels that depict pretty realistically the live of spies, their masters and a bureaucracy full of backroom politics with a distinguished disregard for the very spy who risked his life for them. A huge contrast to the James Bond action-packed books and movies. History has unfortunately shown that the success of intelligence services is mostly measured by their failures and rarely by their successes, because the latter often should stay secret to remain a success.

Filter this blog by the label espionage and you will encounter many failures, tormented spies, executions and imprisonment. They often leave behind lots of debris, if not their life. The not so glorious life of spies, as Le Carré described so masterfully in his books.

From his Cold War marvels such as The Spy Who Came In from the Cold, Tinker Tailor Soldier Spy, A Small Town in Germany, A Perfect Spy or his brilliant but introvert spy catcher George Smiley, to his more recent and more critical Our Kind of Traitor, Legacy of Spies or Agent Running in the Field. All these, and many more books Le Carré wrote, and were filmed, show the game of espionage, all but glamorous, often taking a heavy toll on people involved.

Update: His last book Silverview was released in October 2021. I also took the change to read his first book again, the 1961 Call for the Dead that intruduced the famous secret service agent George Smiley.

He also wrote The Pigeon Tunnel: Stories from My Life, a splendid biography with countless dramatic, hilarious and weird events, with all kinds of people, honourable or questionable, that he encountered. Only a former MI5/MI6/secretary/consul/journalist could have lived such a curious life, of course neither confirmed nor denied. Le Carré's real legacy for spies is the knowledge that their life won't be all that great.

John Le Carré, the spy novel master who made it almost impossible for writers to create a credible spy with a loyal wife, a successful career, and caring superiors. He will forever remain my favourite writer of stories that could have been so beautiful but end so tragic.

Below some of the rare interviews David Cornwell gave. Or was it John Le Carré? One thing's for sure, we'll miss him dearly.

60 Minutes archives: Le Carré

In a CBC 2017 audio interview with John Le Carré (67 min), he talks about his early life, his work for the intelligence service, the characters in his books, the TV series and movies, and shares his view on contemporary politics. A Conversation with John le Carré (27 min) is a 2002 video interview about his books, the Cold War and intelligence services.

In the CIA Studies in Intelligence Volume 61 No 1, historian David Robarge wrote A Review of The Pigeon Tunnel (pdf, archived).  More about John Le Carré's life at The Guardian's Obituary.