Similar for power, except that a doubling of power is +3dB. A decibel is a ratio between two voltages or powers and is stated as a logarithmic change, so if a voltage is halved it has a relative level of -6dB, or double, it has +6dB of gain. Hertz is the name given to a number of cycles-per-second or frequency, for instance, human hearing is acknowledged to be 20Hz to 20000Hz.
What is the relationship between hertz and decibels? For sound power the dimension is Watt the usual reference value is 1 PicoWatt (pW).ģ. For instance, the dimension of the variable in sound is Pascal the reference value is 20 micro pascals. This reference value and the variable in question have the same dimension. It is based on the ratio of a variable and a corresponding reference variable. One decibel (0.1 bel) equals 10 times the common logarithm of the power ratio.Ģ. (1) 10lg2 = lg2^10 = lg1024, and because lg1000 = 3, 10lg2≠3, but very close.ĭecibel (dB), unit for expressing the ratio between two physical quantities, usually amounts of acoustic or electric power, or for measuring the relative loudness of sounds. If the transmit power is 1W, the converted value in dBm unit should be: 10lg (1000mW/1mW) = 30dBm
If the transmit power is 1mW, the value after conversion in dBm unit should be: 10lg (1mW/1mW) = 0dBm The calculation formula is: dBm = 10lg (power value/1mW) -10dBm, the power is multiplied by 1/10ĭBm and W are a unit that represents the absolute value of power.+10dBm, the power is multiplied by 10 times.The formula for converting arbitrary power P(mW) to x(dBm) is as follows:įor example, the conversion of 1 milliwatt (1 mW) into dBm is 0 dBm the conversion of 1 Watt (1 Watt) is 30 dBm. Such as:ĭBm is written as decibel relative to one milliwatt, which is the absolute value of power, and it is only a relative value different from dB. The introduction of dB is to change the multiplication and division relationship into an addition and subtraction relationship, which is more convenient for engineering calculations. It couldn't be simpler, that is, a very large (followed by a long string of 0s) or a very small (preceded by a long string of 0s) number is relatively short. If the power of A is 46dBm and the power of B is 40dBm, it can be said that A is 6dB greater than B.If the power of A is twice as large as the power of B, then 10 lg A/B = 10 lg 2 = 3dB.The calculation formula is: when calculating how many dB the power of A is larger or smaller than that of B, it can be calculated according to the formula 10 lg A/B. dB = 20lgX, often used for voltage/current gain -3db means that the amplitude becomes the original (radix 2)/2, which is 0.707 times, 20lg ((radix 2)/2) = -3.ĭB is the unit of power gain and represents a relative value. (2) A unit that represents the ratio of two voltage or current values or similar sound quantities (such as sound pressure or particle velocity), equal to 20 times the common logarithm of the voltage or current ratio, if the two voltages or currents are at the same Words measured on the resistance. This parameter is mostly used for two-dimensional graphics analysis. dB = 10lgX, often used to calculate the bandwidth by power -3db means that the power becomes 1/2 of the original, 10lg0.5 = -3, -3dB is equivalent to 0.5 in the decimal system a drop of 3dB is a power drop the half, -3dB point refers to the half power point. (1) A unit that represents the ratio of two kinds of electric or acoustic power, which is equal to 10 times the common logarithm of the power ratio. It is also a unit for measuring the relative loudness of sound.
First of all, dB (Decibel) is a unit that characterizes the relative value, that is, the ratio of two kinds of electric or sound power or the ratio of two voltage or current values or similar sound quantities.
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