Path: ...!3.eu.feeder.erje.net!feeder.erje.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Cursitor Doom Newsgroups: sci.electronics.design Subject: Re: dBs Date: Sun, 26 May 2024 17:58:48 -0000 (UTC) Organization: A noiseless patient Spider Lines: 18 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Sun, 26 May 2024 19:58:48 +0200 (CEST) Injection-Info: dont-email.me; posting-host="81079c507858f4224e8e635fbc04d78a"; logging-data="3672111"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+8fqknl0JCmEZuT6/lA4Roe371oFoZUC4=" User-Agent: Pan/0.149 (Bellevue; 4c157ba) Cancel-Lock: sha1:3ddABBqKM6A47RTc9RwD+cUP/Ao= Bytes: 1767 On Sun, 26 May 2024 19:25:41 +0200, Jeroen Belleman wrote: > On 5/26/24 19:09, Cursitor Doom wrote: >> I'm feeling cognitively-declined today, probably as a consequence of my >> vast age and general ignorance of matters mathematical and everything >> else in fact, with the sole exception of "fatuous conspiracy theories." >> Can some kind soul assist? >> If my RF power meter is reading -13dbm when there's a 20dB attenuator >> in line, what is the true power level, please? >> I've got an exhaustive App Note from Rhode & Schwartz which claims to >> cover everything about decibels, but, er, doesn't. >> >> CD. > > That would be -13 + 20 = +7dBm, provided that impedances are matched > everywhere. I was under the impression that one couldn't simply just add dBs to dBms?