Pulse-amplitude modulation is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Pulse-amplitude modulation is now rarely used, having been largely superseded by pulse-code modulation, and, more recently, by pulse-position modulation.
... 4 - Russo-Japanese War: Russian troops in Korea retreat toward Manchuria followed by 100,000 Japanese troops.
April 30 - Louisiana Purchase Exposition World's Fair ...