設備の維持費、AMはFMの約50倍 AM（Amplitude Modulation）ラジオ放送は「中波放送」とも呼ばれ、日本では526.5〜1606.5 kHzという周波数を使用しています。AMの特徴は、電波が遠くまで届くということ。電波は山々を回り込んで伝わるため、ラジオ事業者は出力の ...

A starry-eyed few thousand owners of the latest fangled radio sets in areas around New York City, Boston, Washington, Columbus (Ohio), Chicago and Milwaukee, nowadays enjoy radio entertainment that is ...

Modulation is the act of translating some low-frequency or baseband signal (voice, music, and data) to a higher frequency. Why do we modulate signals? There are at least two reasons: to allow the ...

AM and FM radio before 1920 -- Congestion and frequency-modulation research, 1913-1933 -- RCA, Armstrong, and the acceleration of FM research, 1926-1933 -- The serendipitous discovery of staticless ...