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 ...

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 ...

For high-speed and large-capacity optical communication applications and improvement of accuracy in microwave generation and evaluation equipment Results: NTT and their partners have developed a ...

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 ...