phy1020.DVI

Shortwave broadcast content typically includes news and cultural features from that country, and often

propaganda as well. Shortwave stations are not assigned a single fixed frequency the way our AM and

FM stations are. Instead, they broadcast in blocks of an hour or so in length, with each block at a

specific time and frequency, and in a specific language directed to a particular part of the world. And

the broadcast schedules are often changed throughout the year. For this reason, a printed or on-line

shortwave broadcast guide is helpful for finding times and frequencies of English-language broadcasts

directed to North America.

Some of the best known shortwave stations are:

• Voice of America(United States)


• Radio Canada International(Canada)


• BBC World Service(United Kingdom)


• Radio Deutsche Welle(Germany)


• Radio Sputnik, (formerlyRadio MoscowandVoice of Russia; Russia)


• Radio Australia(Australia)


• China Radio International(formerlyRadio Peking; China)

Just very recently, a number of these stations (marked with an asterisk) have stopped broadcasting by

radio, in favor of Internet service.

• Television.Television signals are sent in much the same way as radio signals, with information about
  the television picture being sent along with the audio. Television signals were encoded by frequency
  modulation until the switch to digital television in 2009. Television channels are broadcast in several
  contiguous “blocks” of frequencies, as shown in Table 43-1. Each television channel is 6 MHz wide.
  Originally, with analog television this was to to allow room for both the video signal (lower part of the
  band) and audio signal (upper part of the band). Now with digital television, each channel requires less
  “bandwidth”, and so television stations often divide their 6 MHz channel into several sub-channels,
  each carrying different programming.

Table 36-1. Television channel frequencies.^1

Channels Frequencies (MHz)

2-4 54-72

5-6 76-88

7-13 174-216

14 - 36 470 - 608

37 - 61 614 - 764

62 - 64 776 - 794

• Cellular telephone.Cellular telephone transmissions occur over a range of frequencies lying between
  800 MHz and 2700 MHz. At these high frequencies, radio signals do not travel very far, so cellular tele-
  phone relies on a nation-wide system of “repeater” transmitters, which receive signals and re-transmit
  them until they reach their destination. (The range of each repeater is the “cell” of cellular telephone.)


• Amateur radio.Radio amateurs have access to a number of blocks of frequency all over the radio fre-
  quency spectrum. They use these for informal hobby chatting (calledragchewing), emergency commu-
  nications, and experimenting with radio technology. Transmitting on the amateur radio bands requires
  an amateur radio license from the Federal Communications Commission.

(^1) There is no television channel 1. Channel 1 existed at one time, but was eliminated by the Federal Communications Commission in
1948 as part of negotiating competing interests in the radio frequency spectrum.