What is attenuation?
Attenuation is a general term referring to when any type of signal -- digital or analog -- reduces in strength. Sometimes called loss, attenuation is a natural consequence of signal transmission over long distances.
Attenuation is important in telecommunications and ultrasound applications. It's critical to determining signal strength as a function of distance. Minimizing the loss of attenuation is important in microwave, wireless and cellular applications because an optical data link depends on modulated light reaching the receiver with enough power to be correctly demodulated. Attenuation reduces this power, resulting in a loss of the transmitted light signal.
In conventional and fiber optic cables, specify attenuation by the number of decibels (dB) per foot, 1,000 feet, kilometer or mile. The less attenuation per unit of distance, the more efficient a cable is.
Attenuation in networking
In computer networking, attenuation is the loss of communication signal strength measured in decibels. As the attenuation rate increases, the transmission, such as a phone call or an email a user tries to send, becomes more distorted.
Attenuation occurs on computer networks because of the following factors:
- Range. Both wired and wireless transmissions gradually dissipate in strength over longer distances.
- Interference. Radio interference, weather or physical obstructions, such as walls, dampen communication signals on wireless networks.
- Wire type and size. Thinner wires suffer from more attenuation than thicker wires on wired networks.
Line attenuation on a Digital Subscriber Line network measures signal loss between a DSL provider's access point and an endpoint. Attenuation is critical on DSL networks. When line attenuation values are too large, it might restrict available data rates. Line attenuation values on a DSL connection are typically between 5 dB and 50 dB. The lower the values, the stronger the signals.
Wi-Fi supports dynamic rate scaling, which enhances the distance at which wireless devices can connect to each other in exchange for lower network performance at longer distances. Depending on the line's transmission quality, dynamic rate scaling automatically regulates the connection's maximum data rate up or down in fixed increments.
How to measure attenuation
The extent of attenuation is usually expressed in decibels but can also be expressed in voltage.
Attenuation in decibels
Ps is the signal power at the transmitting end (source) of a communications circuit, and Pd is the signal power at the receiving end (destination). In this paradigm, Ps > Pd. Use the following formula to determine the power attenuation -- Ap -- in decibels.
Ap = 10 log10(Ps/Pd)
Attenuation in voltage
In this equation, Av is the voltage attenuation in decibels. Vs is the source signal voltage, and Vd is the destination signal voltage. Use the following formula to determine Av.
Av = 20 log10(Vs/Vd)
How to increase signal strength to prevent attenuation
Amplification is a technique to increase signal strength to prevent attenuation. Signal amplification electrically increases a line signal's strength by one of several methods. On computer networks, amplification typically includes logic for noise reduction to prevent the underlying message data from becoming corrupted.
A network repeater device integrates a signal amplifier into its circuitry. Repeaters act as an intermediary between two message endpoints and boost signal strength to overcome attenuation. This is helpful for transmitting long-distance signals via cable. This greatly increases the maximum communication range.
The repeater performs the following tasks:
- Receives data from the original sender or another upstream repeater.
- Processes data through the amplifier.
- Transmits the stronger signal forward to its ultimate destination.
In addition to repeaters, directional antennas and other antenna upgrades also work well to boost signals.
Attenuation in other contexts
Attenuation is also used in contexts other than computer networking. Sound mixers and audiophiles use attenuation techniques to manage sound levels when blending different audio recordings.
Attenuation is also frequently used in the radiology field to discuss the characteristics of an anatomical structure represented in an X-ray.
In brewing, attenuation refers to the process of converting sugars into alcohol and carbon dioxide by fermentation. The greater the attenuation, the more sugar converts into alcohol. If a beer is more attenuated, then it is drier and more alcoholic than a beer that is less attenuated.
