【 Weak current college 】 fast computation power units

<br> <BR> If you are sure to make wireless communications experience these units, dB, dBi, dBd, dBc, dBm, dBw. .Simple to explain: <BR> 1, dBdB is a characterization of the value of the relative value, the ratio of pure, saying only that the relative size of the relationship between two quantities, there is no unit, when considering a power of power compared to larger or smaller number of B .a dB, according to the following formula: 10log (A power / B power), if compared with the voltage between the two terms, use 20log (A V / B voltage). .<BR> [Patients] A B power than double the power, then 10lg (A power / B power) = 10lg2 = 3dB. .In other words, the power of a great power than the B 3dB. .Conversely, if B of A's power is the power of the half, the power of a small power than B 3dB. .<BR> 2, dBi, and dBd dBddBi and the antenna power gain is the amount of both a relative value, but not the same as the reference standard. .a reference for the whole dBi directional antenna, dBd point of reference for the dipole, so the two are slightly different. .Generally believed that the same gain, represented by dBi dBd be expressed than larger 2.15. .<BR> [Patients] for the side of the antenna gain 16dBd, which converted into units of dBi gain when compared with 18.15dBi (generally ignore decimal places, as 18dBi). .<BR> [Patients] 0dBd = 2.15dBi. .<BR> 3, dBcdBc is a relative value, said power unit, with exactly the same as the calculation of dB. .In general, dBc relative to the carrier (Carrier) power is concerned, in many cases, used to measure the relative value of the carrier power, as used to measure interference (co-channel interference, intermodulation interference, crosstalk, with .outside interference, etc.) and coupling, spurious and so the relative value. .Where the introduction of dBc, in principle, can also use dB instead. .<BR> 4, dBmdBm is an absolute value of said power (1mW power can also be considered as a benchmark is a ratio) is calculated as: 10log (power value / 1mw). .<BR> [Patients] If the power P is 1mw, after converted into dBm 0dBm. .<BR> [Patients] to 40W of power, according to dBm units after conversion value should be: 10log (40W/1mw) = 10log (40000) = 10log4 +10 log10000 = 46dBm. .<BR> 5, dBw with dBm as, dBw is a unit of the absolute value of said power (1W power can also be considered as a benchmark is a ratio) is calculated as: 10log (power value / 1w). .dBw and conversion between dBm is: 0dBw = 10log1W = 10log1000mw = 30dBm. .<BR> [Patients] If the power P is 1w, after conversion to dBw 0dBw. .<BR> Short, dB, dBi, dBd, dBc is the ratio between two quantities, indicating the relative size between the two quantities, and dBm, dBw is that the absolute size of the value of the power. .In dB, dBm, dBw calculation, should pay attention to basic concepts, with a dBm (or dBw) by another dBm (dBw), the result is dB, such as: 30dBm-0dBm = 30dB. .In general, in engineering, dBm (or dBw) and dBm (or dBw) only between the addition and subtraction, multiplication and division do not. .The most used is the subtraction: dBm dBm actually two power by dividing the signal power and noise power division is the signal to noise ratio (SNR). .Add dBm dBm power is actually multiplied by two. .<BR> DBm into the calculation method of W's mouth (from MSCBSC Mobile Communication Forum) <BR> <BR> dBm is an absolute value of said power (1mW power can also be considered as a benchmark is a ratio), calculated .formula is: 10log (power value / 1mw). .W here will dBm into the mouth is the first rule to remember operator "a benchmark" and the "two principles": <BR> "1 benchmark": 30dBm = 1W <BR> "2 principles": <BR> .1) +3 dBm, the power by 2 times;-3dBm, power by 1 / 2 <BR> example: 33dBm = 30dBm +3 dBm = 1W × 2 = 2W <BR> 27dBm = 30dBm-3dBm = 1W × 1 / 2 = 0.5W .<BR> 2) +10 dBm, power by 10 times;-10dBm, the power by 1 / 10 <BR> example: 40dBm = 30dBm +10 dBm = 1W × 10 = 10W <BR> 20dBm = 30dBm-10dBm = 1W × 0.1 = 0.1 .W <BR> more simply written as: 30 is the benchmark, the whole is equal to 1W, swap is not difficult, port count can be completed. .Plus 3 multiplied by 2, plus 10 multiplied by 10; minus 3 divided by 2, minus 10 divided by 10. .<BR> DBm almost all integers above are available, "a benchmark" and the "two principles" into W. .<BR> 44dBm = 30dBm +10 dBm +10 dBm-3dBm-3dBm <BR> = 1W × 10 × 10 × 1 / 2 × 1 / 2 <BR> = 25W <BR> 32dBm = 30dBm +3 dBm +3 dBm +3 dBm +3 dBm .-10dBm <BR> = 1W × 2 × 2 × 2 × 2 × 0.1 <BR> computational techniques: <BR> +1 dBm and +2 dBm computing skills <BR> +1 dBm = +10 dBm-3dBm-3dBm-3dBm <BR .> = X × 10 × 1 / 2 × 1 / 2 × 1 / 2 <BR> = X × 1.25 <BR> +2 dBm =- [email = 10dBm +3 dBm +3 dBm +3 dBm +3 dBmwww.mscbsc.com3P # v / .@ (k% a (i2n8h] 10dBm +3 dBm +3 dBm +3 dBm +3 dBmwww.mscbsc.com3P # v / @ (k% a (i2n8h [/ email] <BR> = X × 0.1 × 2 × 2 × 2 × 2 .<BR> = X × 1.6 <BR> in the calculation, and sometimes the law can be transformed according to the above-1dBm and-2dBm, achieve rapid mouth of purpose, namely: <BR>-1dBm =- 10dBm +3 dBm + .3dBm +3 dBm <BR> = X × 0.1 × 2 × 2 × 25 <BR>-2dBm =- 3dBm +1 dBm <BR> = X × 1 / 2 × 1.25 <BR> = X × 0.625 <BR> Example 3: .51dBm = 30dBm +10 dBm +10 dBm +1 dBm <BR> = 1W × 10 × 10 × 1.25 <BR> = 125W <BR> cases 4:38 dBm = 30dBm +10 dBm-2dBm <BR> = 1W × 10 × 0.625 <BR> .= 6.25W <BR> port operator that is, is not that simple ah? do you remember? <BR> another: dBw and W conversion <BR> / dBw and dBm, like, dBw is an absolute value of said power .units (1W power can also be considered as a benchmark is a ratio) is calculated as: 10log (power value / 1w). <BR> dBw and conversion between dBm is: 0dBw = 10log1W = 10log1000mw = 30dBm. < .BR> If the power P is 1W, after conversion to dBw 0dBw. <BR> short, dB, dBi, dBd, dBc is the ratio between two quantities, indicating the relative size between the two quantities, and dBm, dBw the .is that the absolute size of the value of the power. in dB, dBm, dBw calculation, should pay attention to basic concepts, with a dBm (or dBw) by another dBm (dBw), the result is dB, such as: 30dBm-0dBm = .30dB. generally speaking, in engineering, dBm and dBm (or dBw and dBw) only between the addition and subtraction, not multiplication and division. And the most used is the subtraction: dBm dBm actually two power by dividing the signal power .division is the signal to noise ratio and noise power (SNR). dBm dBm increase is actually two power multiplied. <BR> <BR> <BR> <BR>.