A Comparison of Current Broadcast Amplitude-Modulation Techniques

From the beinning, plate moduladon has been the dominant method of modulation used in commercial amplitude-modulation (AM) broadcast transmitters. Recently, however, alternate modulation schemes have been employed in commercial transmitters in growing numbers, namely, pulse-duration modulation (PDM), modified Doherty, and modified Chireix (Ampliphase). This paper discusses traditional plate modulation and compares it, critically, to the newer methods being employed. Performance parameters and economic factors of each of the systems are reviewed and compared. A tutorial approach is used.