Radio

1
Radio

• Chapter 7

2
Basic Radio Facts

• 11,000 radio stations in U.S.
• 6.6 radio receivers in average HH
• More people receive their morning news from radio
  than from any other medium.

3
Radio technology

• Electromagnetic spectrum

4
Radio technology

• modulation means to change
• AM Amplitude modulation means to change the
  amplitude of the electromagnetic waves.

5
Radio technology

• modulation means to change
• FM Frequency modulation means to change the
  frequency of the electromagnetic waves.

6
Radio technology

• Radio uses the electromagnetic spectrum that
  exists in nature.
• 1895 Marconi sent a wireless code through the
  electromagnetic spectrum.
• The first application of this technology was for
  ships at sea.
• 1906 Reginald Fessenden sent music over the
  air.

7
Radio technology

• Bounce back effect - AM waves bounce off the
  ionosphere and follow the earths contour.
• FM waves dont bounce back therefore have a
  shorter range.
• Pp. 156, 157

8
Radio history

• KDKA, 1920 1st licensed, commercial station
• NPR National Public Radio went on air in 1970.