Am Fri, May 16, 2025 at 10:38:04AM +0200 schrieb Johannes Berg: > On Fri, 2025-05-16 at 16:15 +0800, Chen-Yu Tsai wrote: > > > The frequencies 5470 - 5725 have a power of 500 mW. It results in 26 dBm. But I > > > believe 27 dBm are allowed. > > Seems like. But units are hard... > > The link in the db went stale, but the current versions > > https://urldefense.com/v3/__https://www.bundesnetzagentur.de/SharedDocs/Downloads/DE/Sachgebiete/Telekommunikation/Unternehmen_Institutionen/Frequenzen/Allgemeinzuteilungen/MobilfunkDectWlanCBFunk/WLAN_5GHz_pdf.pdf?__blob=publicationFile&v=1__;!!I9LPvj3b!Hih48oBC7IPvu59VI1FRTqSb45uwWEnAELFqlK_ubfJdtkTnODDPuyA5gG6olCgbiPxC6m0zQdcuNJ3nzRJ1RJ_PT6ux0w$ > > states (page 5): > > -------------------- > Frequenzband 5470–5725 MHz > ... > Maximale mittlere EIRP für > bandinterne Aussendungen > > 1 W > Ausnahmen: > für Anlagen in Straßenfahrzeugen gilt eine maximale > mittlere EIRP von 200 mW. > > ... > > Maximale mittlere EIRP-Dichte für > bandinterne Aussendungen > > 50 mW/MHz in jedem 1 MHz-Band > > ... > > Sendeleistungsregelung (TPC) > > TPC muss durchschnittlich einen Abschwächungsfaktor von > mindestens 3 dB gegenüber der höchstzulässigen > Sendeleistung der Systeme erbringen; oder ohne TPC muss die > höchstzulässige mittlere EIRP und die Obergrenze für die > entsprechende mittlere EIRP-Dichte um 3 dB verringert > werden. > -------------------- > > > So to be _really_ precise you'd end up with 1W reduced by 3dB which of > course _is_ precisely 27dBm since 1W is 10^30 or precisely 30 dBm. > > (Except in "street vehicles", apparently. Rail has its own things, so I > guess that really does mean cars/trams/etc.) > > But given the unit conversions are hard, we should probably just do this > in the db in dBm? > > johannes I referred to the following EU Rules: * ETSI EN 300 328 V2.2.2 (2.4 GHz) * ETSI EN 301 893 V2.1.1 (5 GHz) * ETSI EN 300 440 V2.2.1 (5.8 GHz) The problem with them is that almost always the unit _mW_ is used. And the reduction without TPC then is given in _dBm_. However, for 5.8 GHz (SRD devices) the transmission power is stated as 25 mW. Does the EU Rules means 14 dBm or only 13 dBm are allowed? Best regards Alexander Wilhelm
