On 4 Feb 2005 20:02:05 -0800, "jason" wrote:

Hello to all that Helps
You are all very kind and genius.
It is first time I asked question in newsgroup and I received so many
kind answers.
I am so happy. Thanks a lot

So from what you have all explained, can I bold enough to say that I
can add any value in db and any value in dbm together without
converting to one db or dbm unit because they are in the ratio form and
having virtually the same 10log (P1/P2) formula and nothing else more??
Please verify

Dear Jason,

I am sorry to say that I cannot agree with your conclusion.

In my opinion, in the general case, you can NOT add dB and dBm. They
have different applications and were not intended to be added
together.

A quantity expressed in dBm is intended to convey, or imply, a
specific power level in a specific load impedance. On the other hand
the dB is NOT so defined. Therefore, I cannot think of a situation in
which you could simply add them together and have a result that anyone
would be able to iterpret at face value.


Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html