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Wartime Radio: The Secret Listeners

Direction-Finding Wireless Set (BBC photo) - RF CafeI have written often about the many contributions that hobbyists make to various fields of technology. Often times the efforts put out and methods used by amateurs are on par with those of professionals; the main difference between the two being that amateurs do not get paid for their work. This archived BBC video titled "Wartime Radio: The Secret Listeners," sent to me by longtime RF Cafe contributor Gary Steinhour documents how the work of two British amateur radio operators, Russell Clark (call sign THX) and R.J.B. Hippisley (call sign HLX), resulted in a significant strategic advantage during World Wars I and II. The two hams convinced the Admiralty that they were able to intercept German communications to and from submarines (U-Boats), surface vessels, and Zeppelins better than 'professionals' in the service.

After receiving a command position in the Royal Naval Reserve, Hippisley was essentially granted unlimited funds to establish wireless listening stations along the coast, whereupon his operators eventually devised means to triangulate signal origins and thereby locate and track movements of German craft. Highly sensitive vacuum tube circuits and careful antenna construction permitted angular resolutions in the neighborhood of less than 2°. Now having strong advocates within the service of the capabilities that amateur radio operators (including many members of the Radio Society of Great Britain) were able to lend to the country's defense efforts, a previously untapped resource of reliable and patriotic (ensured by proper vetting) technicians quickly grew the force's ranks. They received the designation of VIs (Volunteer Interceptors). Secrecy was maintained remarkably well for nearly three decades until in 1941 the Daily Mirror rag printed an article titled, "Spies Tap Nazi Code." Fortunately, it went largely unnoticed and did no apparent harm.

Relatively few spies were discovered amongst MI8 ranks, and those who were caught were either shot or turned into double agents. Those were the days when survival of nations depended on decisive action without regard for political correctness. Many people today, including yours truly, believe that is still the most efficient approach to security.

Once the Germans figured out that their messages were being routinely intercepted, they began encoding using methods familiar to radio amateurs, so it was not long before the MI8 crew figured out what was going on. The establishment of Hanslope Park in 1941 facilitated large-scale message interception and decryption activities. German secret service and Gestapo messages were intercepted in such great numbers that cryptographers were able to discern the entire network of broadcast stations, and even uniquely identify German operators by commonly mentioned towns, girlfriends, and families. This is the kind of scenario by which the old saying "loose lips sinks ships" got its origin. British intelligence exploited the back door entry into the German secret service by feeding false information to their operators, one result of which was the capturing of many spies who would be sent based on disinformation. "Operation Mincemeat" was a particularly spectacular - if gory -example.

If you have 30 minutes to spare and an interest in communications history, this film is well worth your time.






- Notice at around 5:20 on the video there is what appears to me a mechanized semaphore device that is signaling along with the sailor.

- 'R.S.S.' here is the Radio Security Service (MI8), not the present day RSS (Rich Site Summary)

- Notice at 19:15 the slide rule sitting on the desk of the direction finding station operator.

- Hugh Trevor Roper, one of the brainiacs behind WWII efforts, reminds me strongly of Charles Emerson Winchester, III, in M.A.S.H.



Posted September 24, 2014

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Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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