Editing Decibel (section)

=== Radio power, energy, and field strength ===
; [[dBc|dB{{sub| c}}]] : relative to carrier – in [[telecommunications]], this indicates the relative levels of noise or sideband power, compared with the carrier power. Compare dB{{sub| C}}, used in acoustics.
; dB{{sub| pp}} : relative to the maximum value of the peak power.
; dB{{sub| J}} : energy relative to 1&nbsp;[[joule]]. 1&nbsp;joule&nbsp;= 1&nbsp;watt second&nbsp;= 1&nbsp;watt per hertz, so power spectral density can be expressed in dB{{sub| J }}.
; [[dBm|dB{{sub| m}}]] : dB(mW) – power relative to 1&nbsp;[[milliwatt]]. In the radio field, dB{{sub| m}} is usually referenced to a 50&nbsp;Ω load, with the resultant voltage being 0.224&nbsp;volts.<ref>{{cite book |last=Carr |first=Joseph |author-link=Joseph Carr |year=2002 |title=RF Components and Circuits |publisher=Newnes |isbn=978-0750648448 |pages=45–46 }}</ref>
; dB{{sub| μV/m }}, dB{{sub| uV/m }}, or dB{{sub| μ }} :<ref name="dBμ">{{cite web |title=The dBμ vs. dBu mystery: Signal strength vs. field strength? |date=24 February 2015 |website=Radio Time Traveller (radio-timetraveller.blogspot.com) |type=blog |via=blogspot.com |url=http://radio-timetraveller.blogspot.com/2015/02/the-db-versus-dbu-mystery-signal.html |access-date=13 October 2016 }}</ref> dB(μV/m) – [[electric field strength]] relative to 1&nbsp;[[microvolt]] per [[meter]]. The unit is often used to specify the signal strength of a [[television]] [[broadcast]] at a receiving site (the signal measured ''at the antenna output'' is reported in dBμ{{sub| V}}).
; dB{{sub| f}} : dB(fW) – power relative to 1&nbsp;[[femtowatt]].
; dB{{sub| W}} : dB(W) – power relative to 1&nbsp;[[watt]].
; dB{{sub| k}} : dB(kW) – power relative to 1&nbsp;[[kilowatt]].
; dB{{sub| e}} : dB electrical.
; dB{{sub| o}} : dB optical. A change of 1&nbsp;dB{{sub| o}} in optical power can result in a change of up to 2&nbsp;dB{{sub| e}} in electrical signal power in a system that is thermal noise limited.<ref>{{cite journal |last1=Chand |first1=N. |last2=Magill |first2=P.D. |last3=Swaminathan |first3=S.V. |last4=Daugherty |first4=T.H. |year=1999 |title=Delivery of digital video and other multimedia services {{nobr|( > 1 Gb/s}} bandwidth) in passband above the 155&nbsp;Mb/s baseband services on a FTTx full service access network |journal=Journal of Lightwave Technology |volume=17 |issue=12 |pages=2449–2460 |doi=10.1109/50.809663 }}</ref>