AM stereo: five competing options

The name of the game in consumer audio is stereo. Phonograph record manufacturers dropped monaural products from their catalogs years ago, and music lovers of all persuasions now find the FM band predominantly filled with stereo broadcasts. However, AM radio listeners are still stuck with obsolete monaural sound - not because of lagging technology, but because AM broadcasters showed little initial interest in stereo. The Federal Communications Commission (FCC) tabled AM stereo proposals in the early 1960s to encourage the growth of FM stereo. But the situation is changing dramatically. The AM broadcasters now proclaim they need a stereo option to stay competitive with FM, and broadcast-equipment manufacturers are anxious to oblige. Five competing AM stereo systems are now before the Commission; one of them is likely to be proposed for commercial use later this year. Here's a look at all five candidates- and a challenge: Can you predict which system will be chosen, and why? Spectrum will make a summary of your comments public once the FCC has reached its own conclusions on the matter (see box, p. 31).