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How Listeners Thwarted Radio Jamming In Czechoslovakia

Russia-- A field of antennas used for the long-distance skywave jamming.
Russia-- A field of antennas used for the long-distance skywave jamming.

In Czechoslovakia, outside of the Prague Spring’s brief experiment with political liberalization, authorities invested immense financial and technical resources in jamming the signal of RFE’s Czechoslovak Service and other foreign broadcasts. Their purpose was to prevent listeners from accessing uncensored news and information, but listeners found ways to tune in.

The jamming began following Czechoslovakia’s 1948 Communist coup, drawing on Moscow’s technical direction and support. The Soviet Union already had a vast network comprising thousands of jamming stations. Its massive “Skywave” jamming transmitters could target RFE’s signal from Munich thousands of miles away, but not with great efficiency or reliability. The Czechoslovak authorities augmented the effort locally with smaller “groundwave” jamming transmitters stationed outside major cities.

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Because of jamming, tuning in to RFE broadcasts required some ingenuity, but Czech and Slovak listeners were endlessly creative in their attempts at defiance. Some listened at their cottages in the countryside where jamming was weaker. Other listeners remember waiting for power outages because they knew the jammers would also be down during the blackout and they could catch the signal.

“I lived in the Vysocany region [of Prague] from 1974 to about 1981, where I had my radio in the oven when I wasn’t baking anything,” remembered Marta Kubisova, a popular Czech singer blacklisted for her support of the Prague Spring reforms.“There must have been a signal coming through from the chimney because I could hear RFE very clearly.”

Some listeners waited until the sun went down to tune in, as the altered character of the ionosphere at night strengthens radio waves, making them more difficult to jam.

“The local devices jammed the signal in towns, but only within a 20-30 kilometer radius,” said RFE Czechoslovak Service listener Richar Ryvola. “The long- distance jammers were placed near Smolensk and Kaliningrad, Russia. And here was the Achilles heel: in the evenings on frequencies 13, 16, and 19, one could listen to RFE.”

Among the 1968 Prague Spring reforms was a gradual easing of media censorship that included the ending of local jamming operations. On August 21, however, the Soviet Union and Warsaw Pact allies invaded Czechoslovakia, and one of the occupying army’s first steps was to resume jamming of Western broadcasts.

Even while jamming was in full force, RFE had a weekly listenership of 30-40 percent of the adult population between 1963 and 1988, according to research conducted by RFE based on interviews with Czechoslovak citizens traveling abroad.

Jamming would continue until 1988, when the period of greater transparency and openness ushered in by the policy of glasnost in Russia spread across the Soviet Union and Eastern Block, leading to the Velvet Revolution that toppled communism in Czechoslovakia in 1989.

--Emily Thompson