What's the difference between dB and dBW?

[adeel.sid]

Hello to all.
anybody can differentiate b/w dB and dBW.
Are both same??
I also heard that:
to convert dBW to dBm, Add +30.

 

[subharpe]

db log dbw

By definition db is 10 log (Pout/Pin) where P is power. Without reference power or the input power there is no meanng of dB. Sometimes the reference or the input Pin is taken as watt and sometimes in terms of milliwatt. For specifically denoting the reference the notations dBW or dBm are used.
Also as you mentioned:
1dBW = 10 log(Pout/1W) = 10log(Pout/(1000*1mW)) = 10 log(Pout/1mW) - 10log1000 = 1dBm - 30
therefore
1dBm = 1dBW + 30.

 

[TwinT]

Re: dB and dBW

Have in mind that:

dBW, dBm: measures Power, Watts --> dBW, dBm

dB: measures ratios (of voltages, of powers, etc), W/W, V/V ---> dB

Regards

 

[ricksidd]

Re: dB and dBW

dB is a ratio, so you can not judge the exact watt or voltage.
dBW is ratio with respect to 1 Watt. That means you know what is the exact watt.
0dBW = 1W
-Sidd

 

[pngzhi]

Re: dB and dBW

Subharpe is true.