Snap and crackle goes pop

PROPAGANDA, news, curiosity and even espionage were the fuel of short-wave radio broadcasts. Readers of a certain age may recall the thrill of hearing a crackly, venomously worded broadcast from far away, such as the Voice of Free China denouncing the communist bandits on the mainland, or Radio Peace and Progress in Moscow deriding the imperialist hullabaloo about human rights.

The huge advantage of short-wave was that such material was simple to send and hard to stop. Thanks to their high frequency and short wavelength, even low-powered signals can bounce off the ionosphere halfway round the world; anyone can listen. Jamming them—a favourite Soviet tactic, still practised by China today—is an expensive and patchy business.