Taken https://blog.csdn.net/shij19/article/details/52946454
dBm
Physical meaning is: a representation absolute value of the power (power of 1mW can be thought of as a ratio to reference)
A precise formula
The formula is: dBm = 10log (power value / 1mw)
mW=power(10,dBm/10)
W=(power(10,dBm/10))/1000
Second, a rough calculation
"A benchmark": 30dBm = 1W
"Two principles": 1) + 3dBm, power by 2 times; -3dBm, power take 1/2 |
2) + 10dBm, the power by 10 times; -10dBm, power take 1/10
Example: 33dBm = 30dBm + 3dBm = 1W × 2 = 2W
27dBm＝30dBm－3dBm＝1W×1/2=0.5W
Example: 40dBm = 30dBm + 10dBm = 1W × 10 = 10W
20dBm＝30dBm－10dBm＝1W×0.1=0.1W
More simply referred to as:
30 is a reference, equal to 1W whole, not difficult to exchange, it counts to be completed.
Multiplied by 2 plus 3, plus 10 by 10; 3 divided by 2 minus, minus 10 divided by 10 .
Almost all integers are available dBm or more "reference 1" and "2 principle" is converted to W.
Example 1: 44dBm = W?
44dBm=30dBm+10dBm+10dBm－3dBm－3dBm
=1W×10×10×1/2×1/2
=25W
Example 2: 32dBm =?
32dBm=30dBm+3dBm+3dBm+3dBm+3dBm-10dBm
=1W×2×2×2×2×0.1
=1.6W
Computing skills: + 1dBm and computing skills 2dBm of +
+1dBm=+10dBm－3dBm－3dBm－3dBm
=X×10×1/2×1/2×1/2
=X×1.25
+2dBm=－10dBm+3dBm+3dBm+3dBm+3dBmw
=X×0.1×2×2×2×2
=X×1.6
Generally speaking, in engineering, and between dBm dBm (or dBw and dBw) only addition and subtraction, multiplication and division no. The most used is the subtraction: dBm reduction is actually two power divided dBm, signal power and noise power is divided signal to noise ratio (SNR). dBm plus dBm is actually two power multiplied.