Browse Definitions :
Definition

noise

Also see audio noise.

Noise is unwanted electrical or electromagnetic energy that degrades the quality of signals and data.  Noise occurs in digital and analog systems, and can affect files and communications of all types, including text, programs, images, audio, and telemetry.

In a hard-wired circuit such as a telephone-line-based Internet hookup, external noise is picked up from appliances in the vicinity, from electrical transformers, from the atmosphere, and even from outer space.  Normally this noise is of little or no consequence.  However, during severe thunderstorms, or in locations were many electrical appliances are in use, external noise can affect communications.  In an Internet hookup it slows down the data transfer rate, because the system must adjust its speed to match conditions on the line.  In a voice telephone conversation, noise rarely sounds like anything other than a faint hissing or rushing.

Noise is a more significant problem in wireless systems than in hard-wired systems. In general, noise originating from outside the system is inversely proportional to the frequency, and directly proportional to the wavelength.  At a low frequency such as 300 kHz, atmospheric and electrical noise are much more severe than at a high frequency like 300 megahertz.  Noise generated inside wireless receivers, known as internal noise, is less dependent on frequency.   Engineers are more concerned about internal noise at high frequencies than at low frequencies, because the less external noise there is, the more significant the internal noise becomes.

Communications engineers are constantly striving to develop better ways to deal with noise.  The traditional method has been to minimize the signal bandwidth to the greatest possible extent.   The less spectrum space a signal occupies, the less noise is passed through the receiving circuitry.  However, reducing the bandwidth limits the maximum speed of the data that can be delivered.  Another, more recently developed scheme for minimizing the effects of noise is called digital signal processing (digital signal processing). Using fiber optics, a technology far less susceptible to noise, is another approach.

This was last updated in May 2008

Join the conversation

4 comments

Send me notifications when other members comment.

Please create a username to comment.

what is noise generated by
Cancel
vv
Cancel
jet fuel can't melt steel beams.kappa
Cancel
thanbks
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

  • compliance audit

    A compliance audit is a comprehensive review of an organization's adherence to regulatory guidelines.

  • regulatory compliance

    Regulatory compliance is an organization's adherence to laws, regulations, guidelines and specifications relevant to its business...

  • Whistleblower Protection Act

    The Whistleblower Protection Act of 1989 is a law that protects federal government employees in the United States from ...

SearchSecurity

  • payload (computing)

    In computing, a payload is the carrying capacity of a packet or other transmission data unit. The term has its roots in the ...

  • passphrase

    A passphrase is a string of characters longer than the usual password (which is typically from four to 16 characters long) that ...

  • Web application firewall (WAF)

    A Web application firewall (WAF) is a firewall that monitors, filters or blocks traffic to and from a Web application. WAFs are ...

SearchHealthIT

SearchDisasterRecovery

SearchStorage

  • computational storage

    Computational storage is defined as an architecture that couples compute with storage in order to reduce data movement. In doing ...

  • data deduplication

    Data deduplication -- often called intelligent compression or single-instance storage -- is a process that eliminates redundant ...

  • public cloud storage

    Public cloud storage, also called storage-as-a-service or online storage is a service model that provides data storage on a ...

Close