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Radio in US

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发表于 2007-5-22 01:01:27 | 只看该作者 回帖奖励 |倒序浏览 |阅读模式

Why is the last digit of a radio program an odd number.  E. g FM 98.1, not 98.0 or 98.2?
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沙发
发表于 2007-5-22 08:04:58 | 只看该作者

回复:Radio in US


Actually, there are FM 103.4, AM1300, AM1600.....
 


 
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板凳
发表于 2007-5-23 08:06:15 | 只看该作者

You are right. All the FM radios are odd number of


frequency. I checked it today. I tried to use tune to find a radio, but the increment step is 0.2. I can not ajdust the radio to something like 98.2...
 
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地板
发表于 2007-5-23 21:29:42 | 只看该作者

Here seems to be the answer----


FM radio stations all transmit in a band between 88 megahertz (millions of cycles per second) and 108 megahertz. The band is divided into 100 channels, each 200 kHz (0.2 MHz) wide. The center frequency is located at 1/2 the bandwidth of the FM Channel, or 100 kHz (0.1 MHz) up from the lower end of the channel. For example, the center frequency for Channel 201 (the first FM channel) is 88.0 MHz + 0.1 MHz = 88.1 MHz. So there can be a station at 88.1 megahertz, 88.3 megahertz, 88.5 megahertz, and so on. The 200-kilohertz spacing, and the fact that they center on odd numbers is completely arbitrary and was decided by the FCC. In Europe, the FM stations are spaced 100 kilohertz apart instead of 200 kilohertz apart, and they can end on even or odd numbers.
www.ddhw.com

 
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