1. dB=10 log10 (Pout / Pin) Pout: tso zis muaj zog; Tus pin: input lub zog
2. dBm=10 log10 (P / 1mw), yog ib chav ua haujlwm dav siv hauv kev sib txuas lus engineering; nws feem ntau sawv cev ntawm lub zog kho qhov muag nrog 1 milliwatt raws li siv;
3. dBu=10 log10 (P / 1uw)
