In chapter 6, you learn how to use the decibel. The decibel is used in calculation because it is easier to write than using exponents, and it turns multiplication into addition. Although we mostly use computers for radar calculation today, representing numbers in decibel form still makes it easier to communicate.
There is also a decibel calculator available. We recommend you do not use it until you learn how to solve decibel problems. To use it, just enter the appropriate numbers in any box. All the other appropriate numbers will be adjusted
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Why do we use capital letters with the B in dB?The B in dB stands for the Bel, a unit of measure named after Alexander Graham Bell, inventor of the telephone. Since Bell is a name, the unit named after him always begins with a capital letter - Bel. The decibel is 1/10 of a Bel, so the B in decibel is capitalized in the abbreviation dB. When we look at the unit of power, the Watt, it is capitalized for the same reason. The abbreviation for Watt is W. When you examine decibels relative to a watt, the abbreviation is dBW, since Bell and Watt are both people's names. When we use milliwatts, the abbreviation is mW. When you examine decibels relative to a milliwatt, the abbreviation is dBm, since milli is not a person's name. With decibels relative to a square meter, there is no name involved. The abbreviation is dBsm, deciBels relative to a square meter. The proper writing of these terms is dB, dBm, dBW, dBsm. |