Decibel watt

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The decibel watt or dBW is a unit for the measurement of the strength of a signal expressed in decibels relative to one watt. It is used because of its capability to express both very large and very small values of power in a short range of number; e.g., 1 milliwatt = −30 dBW, 1 watt = 0 dBW, 10 watts = 10 dBW, 100 watts = 20 dBW, and 1,000,000 W = 60 dBW.

{\mbox{Power in dBW}}=10\log _{{10}}{\frac {{\mbox{Power in W}}}{1{\mathrm {W}}}}

Compare to dBm, which is referenced to one milliwatt (0.001 W). Certain dBW value in dBm is always 30 more because 1 watt is 1,000 milliwatts, and ratio of 1,000 (in power) is 30 dB; e.g., 10 dBm (10 mW) is equal to −20 dBW (0.01 W).

Although the decibel (dB) is permitted for use alongside SI units, the dBW is not.

See also

Decibel units (dB)
See also
logarithmic unit
link budget
signal noise
telecommunication
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