It is measured in nanowatts.
EDIT: Also, in another comment that I called out (later in this very thread), you said the exact opposite. What part are you talking about? Make up your mind. This thread has thoroughly disproven your concerns for every part of the signal chain involved, and yet you keep flipping what part you are talking about, disregarding that all parts have been discussed now.
I think you are trolling. Wrap yourself in tinfoil and move on.