[Questions] dBm versus dB

Hi all,

I come across with these 2 conversion table

Here's the dBm to watts http://www.cpcstech.com/dbm-to-watt-...nformation.htm

Here's dB to watts
http://www.atim.com/iso_album/db_to_...sion_table.pdf

why is the 2 table the same even with different units of dB and dBm

Cheers
Jason

The first table is correct.
The second table is incorrect. "dB" should be changed to dBm.
dBm is power relative to 1mW. For example , 1mW=10*log(1mW/1mW)=0dBm, and 2mW=10*log(2mW/1mW)=3dBm.

Yes, the second should be changed.
dBm is absolute power unit measure.
dB is relative power unit measure.
So you should say for example:
the max output power of this amp is 30 dBm and its gain (@ a certain polarization) is 15 dB.

Max