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dBm or dB mW (decibel-milliwatts) is a unit of power level expressed using a logarithmic decibel (dB) scale respective to one milliwatt (mW). It is commonly used by radio, microwave and fiber-optical communication technicians & engineers to measure the power of system transmissions on a log scale , which can express both very large and very ...
The decibel watt (dBW or dB W) 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.
A power level of 0 dBm corresponds to one milliwatt, and 1 dBm is one decibel greater (about 1.259 mW). In professional audio specifications, a popular unit is the dBu . This is relative to the root mean square voltage which delivers 1 mW (0 dBm) into a 600-ohm resistor, or √ 1 mW × 600 Ω ≈ 0.775 V RMS .
High-powered transmissions, such as those used in broadcasting, are expressed in dB-millivolts per metre (dBmV/m). For very low-power systems, such as mobile phones , signal strength is usually expressed in dB - microvolts per metre (dBμV/m) or in decibels above a reference level of one milliwatt ( dBm ).
A field level (or root-power level) is a logarithmic quantity used to measure quantities of which the square is typically proportional to power (for instance, the square of voltage is proportional to power by the inverse of the conductor's resistance), etc., with commonly used units neper (Np) or decibel (dB).
−25 dBm astro: cosmic microwave background radiation per square meter 10 −5: 5 × 10 −5: −13 dBm biomed: sound power incident on a human eardrum at the threshold intensity for pain (500 mW/m 2). 10 −3: milli-(mW) 1.55 × 10 −3: −4.7 dBm astro: power per square meter received from the Sun by Sedna at its aphelion 5 × 10 −3: 7 ...
The dBm is an absolute reference level measurement (see Decibel § Suffixes and reference values) with respect to 1 mW power. When the nominal signal power is 0 dBm at the TLP, the test point is called a zero transmission level point, or zero-dBm TLP. The abbreviation dBm0 stands for the power in dBm measured
The decibel unloaded reference voltage, 0 dBu, is the AC voltage required to produce 1 mW of power across a 600 Ω impedance (approximately 0.7746 V RMS). [2] This awkward unit is a holdover from the early telephone standards, which used 600 Ω sources and loads, and measured dissipated power in decibel-milliwatts ( dBm ).