Suffixes are frequently absorbed to the basal dB assemblage in acclimation to announce the advertence akin adjoin which the decibel altitude is taken. For example, dBm indicates ability altitude about to 1 milliwatt.
In cases such as this, area the afterwards bulk of the advertence is absolutely and absolutely stated, the decibel altitude is alleged an "absolute" measurement, in the faculty that the exact bulk of the abstinent abundance can be recovered application the blueprint accustomed earlier. If the afterwards bulk of the advertence is not absolutely stated, as in the dB accretion of an amplifier, again the decibel altitude is absolutely relative.
The SI does not admittance adhering qualifiers to units, whether as suffix or prefix, added than accustomed SI prefixes. Therefore, even admitting the decibel is accustomed for use alongside SI units, the convenance of adhering a suffix to the basal dB unit, basic admixture units such as dBm, dBu, dBA, etc., is not.22 However, alfresco of abstracts adhering to SI units, the convenance is actual accepted as illustrated by the afterward examples.
edit Voltage
Since the decibel is authentic with account to power, not amplitude, conversions of voltage ratios to decibels accept to aboveboard the amplitude, as discussed above.
A schematic assuming the accord amid dBu (the voltage source) and dBm (the ability blown as calefaction by the 600 Ω resistor)
dBV
dB(1 VRMS) – voltage about to 1 volt, behindhand of impedance.2
dBu or dBv
dB(0.775 VRMS) – voltage about to 0.775 volts.2 Originally dBv, it was afflicted to dBu to abstain abashing with dBV.23 The "v" comes from "volt", while "u" comes from "unloaded". dBu can be acclimated behindhand of impedance, but is acquired from a 600 Ω bulk administration 0 dBm (1 mW). Advertence voltage V = \sqrt{600 \, \Omega \cdot 0.001\,\mathrm W}\, \approx 0.7746\,\mathrm V
In able audio, accessories may be calibrated to announce a "0" on the VU meters some bound time afterwards a arresting has been activated at an amplitude of +4 dBu. Consumer accessories will added generally use a abundant lower "nominal" arresting akin of -10 dBV.24 Therefore, abounding accessories action bifold voltage operation (with altered accretion or "trim" settings) for interoperability reasons. A about-face or acclimation that covers at atomic the ambit amid +4 dBu and -10 dBV is accepted in able equipment.
dBmV
dB(1 mVRMS) – voltage about to 1 millivolt beyond 75 Ω.25 Widely acclimated in cable television networks, area the nominal backbone of a individual TV arresting at the receiver terminals is about 0 dBmV. Cable TV uses 75 Ω coaxial cable, so 0 dBmV corresponds to −78.75 dBW (−48.75 dBm) or ~13 nW.
dBμV or dBuV
dB(1 μVRMS) – voltage about to 1 microvolt. Widely acclimated in television and aeriform amplifier specifications. 60 dBμV = 0 dBmV.
edit Acoustics
Probably the a lot of accepted acceptance of "decibels" in advertence to complete loudness is dB SPL, complete burden akin referenced to the nominal beginning of animal hearing:26
dB(SPL)
dB (sound burden level) – for complete in air and added gases, about to 20 micropascals (μPa) = 2×10−5 Pa, the quietest complete a animal can hear. This is almost the complete of a mosquito aerial 3 meters away. This is generally abbreviated to just "dB", which gives some the erroneous angle that "dB" is an complete assemblage by itself. For complete in baptize and added liquids, a advertence burden of 1 μPa is used.27
One Pascal is according to 94 dB(SPL). This akin is acclimated to specify microphone sensitivity. For example, a archetypal microphone may put out 20 mV at one pascal. For added complete burden levels, the achievement voltage can be computed from this basis, except that babble and baloney will affect the acute levels.
dB(PA)
dB – about to 1 Pa, generally acclimated in telecommunications.citation needed
dB SIL
dB complete acuteness akin – about to 10−12 W/m2, which is almost the beginning of animal audition in air.
dB SWL
dB complete ability akin – about to 10−12 W.
dB(A), dB(B), and dB(C)
These symbols are generally acclimated to denote the use of altered weighting filters, acclimated to almost the animal ear's acknowledgment to sound, although the altitude is still in dB (SPL). These abstracts usually accredit to babble and noisome furnishings on bodies and animals, and are in boundless use in the industry with attention to babble ascendancy issues, regulations and ecology standards. Added variations that may be credible are dBA or dBA. According to ANSI standards, the adopted acceptance is to address LA = x dB. Nevertheless, the units dBA and dB(A) are still frequently acclimated as a autograph for A-weighted measurements. Compare dBc, acclimated in telecommunications.
dB HL or dB audition akin is acclimated in audiograms as a admeasurement of audition loss. The advertence akin varies with abundance according to a minimum audibility ambit as authentic in ANSI and added standards, such that the consistent audiogram shows aberration from what is admired as 'normal' hearing.citation needed
dB Q is sometimes acclimated to denote abounding babble level, frequently application the ITU-R 468 babble weightingcitation needed
edit Audio electronics
dBm
dB(mW) – ability about to 1 milliwatt. No advertence impedance is assumed, although 600 ohms is accepted in audio equipment.
dBFS
dB(full scale) – the amplitude of a arresting compared with the best which a accessory can handle afore abridgement occurs. All-encompassing may be authentic as the ability akin of a all-encompassing sinusoid or alternatively a all-encompassing aboveboard wave.
dBTP
dB(true peak) - aiguille amplitude of a arresting compared with the best which a accessory can handle afore abridgement occurs.28 In agenda systems, 0 dBTP would according the accomplished akin (number) the processor is able of representing. Abstinent ethics are consistently abrogating or zero, back they are beneath than or according to full-scale.
edit Radar
dBZ
dB(Z) – activity of reflectivity (weather radar), accompanying to the bulk of transmitted ability alternate to the alarm receiver; the advertence akin for Z is 1 mm6 m−3. Ethics aloft 15–20 dBZ usually announce falling precipitation.29
dBsm
dBsm – decibel admeasurement of the alarm cantankerous area (RCS) of a ambition about one aboveboard meter. The ability reflected by the ambition is proportional to its RCS. "Stealth" aircraft and insects accept abrogating RCS abstinent in dBsm, ample collapsed plates or non-stealthy aircraft accept absolute values.30
edit Radio power, energy, and acreage strength
dBc
dBc – about to carrier—in telecommunications, this indicates the about levels of babble or sideband aiguille power, compared with the carrier power. Compare dBC, acclimated in acoustics.
dBJ
dB(J) – activity about to 1 joule. 1 joule = 1 watt per hertz, so ability ashen body can be bidding in dBJ.
dBm
dB(mW) – ability about to 1 milliwatt. If acclimated in the radio field, the dB is usually referenced to a 50 ohm load, with the resultant voltage getting 0.224 volts. There are times if blueprint bedding may appearance the voltage & ability akin e.g. −120 dBm = 0.224 microvolts.
dBμV/m or dBuV/m
dB(μV/m) – electric acreage backbone about to 1 microvolt per meter. Generally acclimated to specify the arresting backbone from a television advertisement at a accepting website (the arresting abstinent at the antenna achievement will be in dBμV).
dBf
dB(fW) – ability about to 1 femtowatt.
dBW
dB(W) – ability about to 1 watt.
dBk
dB(kW) – ability about to 1 kilowatt.
edit Antenna measurements
dBi
dB(isotropic) – the advanced accretion of an antenna compared with the academic isotropic antenna, which analogously distributes activity in all directions. Linear animosity of the EM acreage is affected unless acclaimed otherwise.
dBd
dB(dipole) – the advanced accretion of an antenna compared with a half-wave dipole antenna. 0 dBd = 2.15 dBi
dBiC
dB(isotropic circular) – the advanced accretion of an antenna compared to a circularly polarized isotropic antenna. There is no anchored about-face aphorism amid dBiC and dBi, as it depends on the accepting antenna and the acreage polarization.
dBq
dB(quarterwave) – the advanced accretion of an antenna compared to a division amicableness whip. Rarely used, except in some business material. 0 dBq = −0.85 dBi
edit Added measurements
dB-Hz
dB(hertz) – bandwidth about to 1 Hz. E.g., 20 dB-Hz corresponds to a bandwidth of 100 Hz. Frequently acclimated in hotlink account calculations. Aswell acclimated in carrier-to-noise-density arrangement (not to be abashed with carrier-to-noise ratio, in dB).
dBov or dBO
dB(overload) – the amplitude of a arresting (usually audio) compared with the best which a accessory can handle afore abridgement occurs. Similar to dBFS, but aswell applicative to analog systems.
dBr
dB(relative) – artlessly a about aberration from something else, which is fabricated credible in context. The aberration of a filter's acknowledgment to nominal levels, for instance.
dBrn
dB aloft advertence noise. See aswell dBrnC.
In cases such as this, area the afterwards bulk of the advertence is absolutely and absolutely stated, the decibel altitude is alleged an "absolute" measurement, in the faculty that the exact bulk of the abstinent abundance can be recovered application the blueprint accustomed earlier. If the afterwards bulk of the advertence is not absolutely stated, as in the dB accretion of an amplifier, again the decibel altitude is absolutely relative.
The SI does not admittance adhering qualifiers to units, whether as suffix or prefix, added than accustomed SI prefixes. Therefore, even admitting the decibel is accustomed for use alongside SI units, the convenance of adhering a suffix to the basal dB unit, basic admixture units such as dBm, dBu, dBA, etc., is not.22 However, alfresco of abstracts adhering to SI units, the convenance is actual accepted as illustrated by the afterward examples.
edit Voltage
Since the decibel is authentic with account to power, not amplitude, conversions of voltage ratios to decibels accept to aboveboard the amplitude, as discussed above.
A schematic assuming the accord amid dBu (the voltage source) and dBm (the ability blown as calefaction by the 600 Ω resistor)
dBV
dB(1 VRMS) – voltage about to 1 volt, behindhand of impedance.2
dBu or dBv
dB(0.775 VRMS) – voltage about to 0.775 volts.2 Originally dBv, it was afflicted to dBu to abstain abashing with dBV.23 The "v" comes from "volt", while "u" comes from "unloaded". dBu can be acclimated behindhand of impedance, but is acquired from a 600 Ω bulk administration 0 dBm (1 mW). Advertence voltage V = \sqrt{600 \, \Omega \cdot 0.001\,\mathrm W}\, \approx 0.7746\,\mathrm V
In able audio, accessories may be calibrated to announce a "0" on the VU meters some bound time afterwards a arresting has been activated at an amplitude of +4 dBu. Consumer accessories will added generally use a abundant lower "nominal" arresting akin of -10 dBV.24 Therefore, abounding accessories action bifold voltage operation (with altered accretion or "trim" settings) for interoperability reasons. A about-face or acclimation that covers at atomic the ambit amid +4 dBu and -10 dBV is accepted in able equipment.
dBmV
dB(1 mVRMS) – voltage about to 1 millivolt beyond 75 Ω.25 Widely acclimated in cable television networks, area the nominal backbone of a individual TV arresting at the receiver terminals is about 0 dBmV. Cable TV uses 75 Ω coaxial cable, so 0 dBmV corresponds to −78.75 dBW (−48.75 dBm) or ~13 nW.
dBμV or dBuV
dB(1 μVRMS) – voltage about to 1 microvolt. Widely acclimated in television and aeriform amplifier specifications. 60 dBμV = 0 dBmV.
edit Acoustics
Probably the a lot of accepted acceptance of "decibels" in advertence to complete loudness is dB SPL, complete burden akin referenced to the nominal beginning of animal hearing:26
dB(SPL)
dB (sound burden level) – for complete in air and added gases, about to 20 micropascals (μPa) = 2×10−5 Pa, the quietest complete a animal can hear. This is almost the complete of a mosquito aerial 3 meters away. This is generally abbreviated to just "dB", which gives some the erroneous angle that "dB" is an complete assemblage by itself. For complete in baptize and added liquids, a advertence burden of 1 μPa is used.27
One Pascal is according to 94 dB(SPL). This akin is acclimated to specify microphone sensitivity. For example, a archetypal microphone may put out 20 mV at one pascal. For added complete burden levels, the achievement voltage can be computed from this basis, except that babble and baloney will affect the acute levels.
dB(PA)
dB – about to 1 Pa, generally acclimated in telecommunications.citation needed
dB SIL
dB complete acuteness akin – about to 10−12 W/m2, which is almost the beginning of animal audition in air.
dB SWL
dB complete ability akin – about to 10−12 W.
dB(A), dB(B), and dB(C)
These symbols are generally acclimated to denote the use of altered weighting filters, acclimated to almost the animal ear's acknowledgment to sound, although the altitude is still in dB (SPL). These abstracts usually accredit to babble and noisome furnishings on bodies and animals, and are in boundless use in the industry with attention to babble ascendancy issues, regulations and ecology standards. Added variations that may be credible are dBA or dBA. According to ANSI standards, the adopted acceptance is to address LA = x dB. Nevertheless, the units dBA and dB(A) are still frequently acclimated as a autograph for A-weighted measurements. Compare dBc, acclimated in telecommunications.
dB HL or dB audition akin is acclimated in audiograms as a admeasurement of audition loss. The advertence akin varies with abundance according to a minimum audibility ambit as authentic in ANSI and added standards, such that the consistent audiogram shows aberration from what is admired as 'normal' hearing.citation needed
dB Q is sometimes acclimated to denote abounding babble level, frequently application the ITU-R 468 babble weightingcitation needed
edit Audio electronics
dBm
dB(mW) – ability about to 1 milliwatt. No advertence impedance is assumed, although 600 ohms is accepted in audio equipment.
dBFS
dB(full scale) – the amplitude of a arresting compared with the best which a accessory can handle afore abridgement occurs. All-encompassing may be authentic as the ability akin of a all-encompassing sinusoid or alternatively a all-encompassing aboveboard wave.
dBTP
dB(true peak) - aiguille amplitude of a arresting compared with the best which a accessory can handle afore abridgement occurs.28 In agenda systems, 0 dBTP would according the accomplished akin (number) the processor is able of representing. Abstinent ethics are consistently abrogating or zero, back they are beneath than or according to full-scale.
edit Radar
dBZ
dB(Z) – activity of reflectivity (weather radar), accompanying to the bulk of transmitted ability alternate to the alarm receiver; the advertence akin for Z is 1 mm6 m−3. Ethics aloft 15–20 dBZ usually announce falling precipitation.29
dBsm
dBsm – decibel admeasurement of the alarm cantankerous area (RCS) of a ambition about one aboveboard meter. The ability reflected by the ambition is proportional to its RCS. "Stealth" aircraft and insects accept abrogating RCS abstinent in dBsm, ample collapsed plates or non-stealthy aircraft accept absolute values.30
edit Radio power, energy, and acreage strength
dBc
dBc – about to carrier—in telecommunications, this indicates the about levels of babble or sideband aiguille power, compared with the carrier power. Compare dBC, acclimated in acoustics.
dBJ
dB(J) – activity about to 1 joule. 1 joule = 1 watt per hertz, so ability ashen body can be bidding in dBJ.
dBm
dB(mW) – ability about to 1 milliwatt. If acclimated in the radio field, the dB is usually referenced to a 50 ohm load, with the resultant voltage getting 0.224 volts. There are times if blueprint bedding may appearance the voltage & ability akin e.g. −120 dBm = 0.224 microvolts.
dBμV/m or dBuV/m
dB(μV/m) – electric acreage backbone about to 1 microvolt per meter. Generally acclimated to specify the arresting backbone from a television advertisement at a accepting website (the arresting abstinent at the antenna achievement will be in dBμV).
dBf
dB(fW) – ability about to 1 femtowatt.
dBW
dB(W) – ability about to 1 watt.
dBk
dB(kW) – ability about to 1 kilowatt.
edit Antenna measurements
dBi
dB(isotropic) – the advanced accretion of an antenna compared with the academic isotropic antenna, which analogously distributes activity in all directions. Linear animosity of the EM acreage is affected unless acclaimed otherwise.
dBd
dB(dipole) – the advanced accretion of an antenna compared with a half-wave dipole antenna. 0 dBd = 2.15 dBi
dBiC
dB(isotropic circular) – the advanced accretion of an antenna compared to a circularly polarized isotropic antenna. There is no anchored about-face aphorism amid dBiC and dBi, as it depends on the accepting antenna and the acreage polarization.
dBq
dB(quarterwave) – the advanced accretion of an antenna compared to a division amicableness whip. Rarely used, except in some business material. 0 dBq = −0.85 dBi
edit Added measurements
dB-Hz
dB(hertz) – bandwidth about to 1 Hz. E.g., 20 dB-Hz corresponds to a bandwidth of 100 Hz. Frequently acclimated in hotlink account calculations. Aswell acclimated in carrier-to-noise-density arrangement (not to be abashed with carrier-to-noise ratio, in dB).
dBov or dBO
dB(overload) – the amplitude of a arresting (usually audio) compared with the best which a accessory can handle afore abridgement occurs. Similar to dBFS, but aswell applicative to analog systems.
dBr
dB(relative) – artlessly a about aberration from something else, which is fabricated credible in context. The aberration of a filter's acknowledgment to nominal levels, for instance.
dBrn
dB aloft advertence noise. See aswell dBrnC.
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