I have a device interface with Pi.
It said its RF output power is 20dBm and 100mW.
what does it mean 20 dBm?
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DougieLawson
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Re: RF interface device Output power
Try looking in the Wiki
https://en.wikipedia.org/wiki/DBm
https://en.wikipedia.org/wiki/DBm
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Re: RF interface device Output power
It means decibels over 1mW.
decibels is a logarithmic scale. Every ten decibels is an increase in power of ten times. So 20dBm is 1mW x 10 X 10 = 100mW.
The gain in an aerial is often given as dBi, which is the gain over a theoretical aerial that radiates equally in all directions. The i stands for "isotropic". No aerial is as bad as an isotropic one; the worst you can get is a dipole, which is about 2.5dBi.
decibels is a logarithmic scale. Every ten decibels is an increase in power of ten times. So 20dBm is 1mW x 10 X 10 = 100mW.
The gain in an aerial is often given as dBi, which is the gain over a theoretical aerial that radiates equally in all directions. The i stands for "isotropic". No aerial is as bad as an isotropic one; the worst you can get is a dipole, which is about 2.5dBi.