A new country has been added to the list of Soviet allies that jam international radio broadcasts: Cuba. Since Radio Mart'i began broadcasting on May 20, the island nation has been jamming the United States government station, which was set up to present news about Cuba that the Reagan administration says is denied to Cubans by their government-controlled news media.
In retaliation for the broadcasts, Cuba also suspended an agreement that partially restored immigration between the two countries. The accord was reached with the US last December.
The interference with Radio Mart'i, which is on the air 14 hours a day, seven days a week, is unlike other Soviet-bloc jamming in that it does not obliterate the broadcasts.
``It's a tone that's being emitted on the frequency. You can still hear the broadcast, but it's annoying,'' said Gregory Lagana, a State Department spokesman.
The jamming affects AM broadcasts on 1180 kHz from Marathon, Fla., and the two shortwave frequencies that the Voice of America (VOA) has used to Cuba for more than 20 years, he adds. Radio Mart'i is run by VOA.
After the Soviet invasion of Afghanistan in 1979, the Soviet Union and its allies resumed jamming international shortwave broadcasts. The practice had been suspended during the era of d'etente.
Jamming is accomplished by transmitting a signal on the same frequency as the station to be jammed. The jamming transmitter generates noise, or nonintelligible transmissions, says Stanley Leinwoll, director of engineering (US) for Radio Liberty-Radio Free Europe.
He says that the Russian-language broadcasts of Radio Liberty, VOA, the British Broadcasting Corporation (BBC), Deutsche Welle (from West Germany), and Kol Israel (the Voice of Israel) are extensively jammed.
He says that now all jamming on a regular basis is done by the Soviet Union and its satellites.
``The number of facilities they have is finite. The number they need to jam is enormous.'' For example, at least 50 jamming stations surround Moscow, he says.
He estimates that the Soviets spend ``a rock-bottom minimum of a quarter of a billion dollars'' a year on jamming. ``That's estimating very conservatively.''
He says that programs in languages other than Russian are jammed: Radio Liberty's services to 12 other nationalities in the Soviet Union; Radio Free Europe (RFE) in Latvian, Lithuanian, Estonian, Polish (``extremely heavily''), Czech, and Bulgarian, but not in Hungarian or Romanian; VOA and the BBC in Polish; and Kol Israel in Yiddish and Hebrew.
Leinwoll says he ``wouldn't be at all surprised'' if Cuba carried through on a threat to blanket the East Coast with Cuban AM-band broadcasts on powerful 500-kilowatt transmitters. Cuban officials are said to be evaluating the content and effect of Radio Mart'i before deciding whether to begin rival broadcasts.
In fact, briefly in 1982, Havana beamed English-language programs to the US on several frequencies including 1040 kHz, interfering with WHO, a 50-kilowatt station in Des Moines. The broadcasts were understood to demonstrate Cuba's ability to retaliate should the US proceed with the Radio Mart'i project, which had then just been proposed.
There is no easy solution to jamming. ``There's really nothing that can be done,'' says Glenn Hauser, editor of the Review of International Broadcasting, ``except retaliation in kind, which is anathema -- as it should be -- to the Western mind.''