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Quick TIPS to calculate between dBm and Watt for RFID signal
1/23/2018 6:08:22 AM / Editor - yoyo / Source - RFID FUWIT

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dBm is a value that represents the absolute value of power (which can also be considered as a ratio based on a power of 1 mW), calculated as 10 log (power value / 1 mw). Here we introduce a method of calculating dBm to W, which is summarized as "1 benchmark" and "2 principles":


1 benchmark:

30dBm=1W


2 principles:

Principle one:

+ 3dB, power by 2 times; -3dB, power by 1/2


Example:

33dBm=30dBm+3dBm=1W×2=2W

27dBm=30dBm-3dBm=1W×1/2=0.5W


Principle two:

+ 10dBm, power by 10 times; -10dBm, power by 1/10


Example:

40dBm=30dBm+10dBm=1W×10=10W

20dBm=30dBm-10dBm=1W×0.1=0.1W


The above can be simply recorded as: 30 is the benchmark, equal to 1W whole, swap is not difficult, the most simple port count. Add 3 times 2, plus 10 times 10; subtract 3 from 2, minus 10 to 10.


The dBm for almost any integer can be converted to W with "1 benchmark" and "2 principles" above.


example 1:

44dBm=?W

44dBm=30dBm+10dBm+10dBm-3dBm-3dBm   

            =1W×10×10×1/2×1/2 =25W


example 2:

32dBm=?W

32dBm=30dBm+3dBm+3dBm+3dBm+3dBm-10dBm

      =1W×2×2×2×2×0.1=1.6W


Calculation skills:


+ 1dBm and + 2dBm calculation skills


+1dBm=+10dBm-3dBm-3dBm-3dBm

           =X×10×1/2×1/2×1/2

           =X×1.25


+2dBm=-10dBm+3dBm+3dBm+3dBm+3dBm

           =X×0.1×2×2×2×2=X×1.6w


In the calculation, sometimes according to the above rules can be transformed into -1dBm and -2dBm, to achieve the purpose of rapid mouth speed, namely:


-1dBm=-10dBm+3dBm+3dBm+3dBm

             =X×0.1×2×2×2

             =X×0.8

-2dBm=-3dBm+1dBm

             =X×1/2×1.25

             =X×0.625


example 3:

51dBm=30dBm+10dBm+10dBm+1dBm

           =1W×10×10×1.25

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