Abstract: In order to reduce bit errors resulting in a space-diversity broad-band digital radio receiver from selective fading, an amplitude dispersion detector detects the amplitude dispersion caused, if any, by the selective fading in each of IF signals produced by the space-diversity reception and produces a detector output having an amplitude variable with the detected amplitude dispersion and used in combining the IF signals. The detector may comprise three band-pass filters having different narrow passbands in the IF band to produce filter outputs with amplitudes dependent on first-order and second-order dispersion components of the amplitude dispersion. Alternatively, the detector may comprise a band-pass filter having a narrow passband repeatedly variable throughout the IF band at a lower frequency to produce a filter output with an amplitude variable with the first-order and the second-order dispersion components and, above all, with a notch-shaped dispersion component.