Transmission loss (TL) in general describes the accumulated decrease in

intensity Intensity may refer to: In colloquial use * Strength (disambiguation) *Amplitude * Level (disambiguation) * Magnitude (disambiguation) In physical sciences Physics *Intensity (physics), power per unit area (W/m2) *Field strength of electric, m ...

of a waveform energy as a wave propagates outwards from a source, or as it propagates through a certain area or through a certain type of structure. It is a terminology frequently used in

radio communication Radio is the technology of telecommunication, communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transm ...

twisted pair Twisted pair cabling is a type of communications cable in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted balanced ...

systems ( PTSN,

Ethernet Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

, etc),

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...

and

acoustics Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician ...

. Measures of TL are very important in the industry of acoustic devices such as

muffler A muffler (North American and Australian English) or silencer (British English) is a device for reducing the noise emitted by the exhaust of an internal combustion engine—especially a noise-deadening device forming part of the exhaust syst ...

s and

sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances ( ranging), communicate with or detect objects o ...

Definition

Measurement of transmission loss can be in terms of

decibels The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a ...

. Mathematically, transmission loss is measured in dB scale and in general it can be defined using the following formula: : TL =

10 \log_ \left\vert \right\vert

dB where: *

W_i

is the power of incident wave coming towards a defined area (or structure); *

W_t

is the power of transmitted wave going away from the defined area (or structure).

Applications

Transmission loss may refer to a more specific concept in one of the fields below: * Transmission loss in electrical engineering describes the decrease of

electrical power Electric power is the rate of transfer of electrical energy within a electric circuit, circuit. Its SI unit is the watt, the general unit of power (physics), power, defined as one joule per second. Standard prefixes apply to watts as with oth ...

along an electrical cable. The term has its origins in

telephony Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunications services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is ...

. * Transmission loss in duct acoustics describes the acoustic performances of a

like system. *Transmission loss in

room acoustics Room acoustics is a subfield of acoustics dealing with the behaviour of sound in enclosed or partially-enclosed spaces. The architectural details of a room influences the behaviour of sound waves within it, with the effects varying by frequency ...

describes the decrease of

sound intensity Sound intensity, also known as acoustic intensity, is defined as the power carried by sound waves per unit area in a direction perpendicular to that area, also called the sound power density and the sound energy flux density. The SI unit of inte ...

that is reduced by a wall or other structure at a given frequency. *Transmission loss in

underwater acoustics Underwater acoustics (also known as hydroacoustics) is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries. The water may be in the oce ...

describes the decrease of

that is reduced by a bubble curtain or other damping structure at a given frequency. The same term is sometimes used to mean propagation loss, which is a measure of the reduction in sound intensity between the sound source and a receiver, defined as the difference between the source level and the

sound pressure level Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone ...

at the receiver.

Types

*Transmission loss types in

fiber-optic communication Fiber-optic communication is a form of optical communication for transmitting information from one place to another by sending pulses of infrared or visible light through an optical fiber. The light is a form of carrier wave that is modul ...

include absorption loss, scattering loss, dispersion loss, radiation loss and coupling loss. *Transmission loss types in twisted pair transmission systems include conductor loss,

dielectric loss In electrical engineering, dielectric loss quantifies a dielectric material's inherent dissipation of electromagnetic energy (e.g. heat). It can be parameterized in terms of either the loss angle or the corresponding loss tangent . Both refer ...

as well as radiation loss.

References

{{Set index article Acoustics Optical quantities Former disambiguation pages converted to set index articles