Browse Definitions:
Definition

Doppler effect

The frequency and wavelength of an electromagnetic field are affected by relative motion. This is known as the Doppler effect . Only the radial (approaching or receding) component of motion produces this phenomenon. The Doppler effect also occurs with acoustic waves.

The Doppler effect is significant in low-earth-orbit (LEO) satellite systems. All LEO satellites are constantly moving relative to each other and to points on the surface. This causes variations in the frequencies and wavelengths of received signals. In geostationary satellite systems, Doppler effect is not a factor unless the end user is on board a spacecraft or high-speed aircraft.

If the source of an EM field is approaching an observer, the frequency increases and the wavelength decreases. If the source is receding, the frequency decreases and the wavelength increases. If there are several observers, each moving radially at different speeds relative to the source of an EM field, every observer will perceive a unique frequency and wavelength for the EM field produced by the source.

A special type of RADAR , called Doppler radar , uses the Doppler effect to ascertain wind velocity in heavy thundershowers, tornadoes, and hurricanes. In a rotating storm such as a hurricane or tornado, the maximum sustained wind speed can be found by measuring the difference in frequency of echoes returned from approaching rain droplets and receding rain droplets. A more primitive form of Doppler radar is used by law enforcement personnel to enforce traffic speed limits.

This was last updated in September 2005

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

SearchSecurity

  • copyright

    Copyright is a legal term describing ownership of control of the rights to the use and distribution of certain works of creative ...

  • keylogger (keystroke logger or system monitor)

    A keylogger, sometimes called a keystroke logger or system monitor, is a type of surveillance technology used to monitor and ...

  • password

    A password is an unspaced sequence of characters used to determine that a computer user requesting access to a computer system is...

SearchHealthIT

SearchDisasterRecovery

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

SearchStorage

  • RAID (redundant array of independent disks)

    RAID (redundant array of independent disks) is a way of storing the same data in different places on multiple hard disks to ...

  • data migration

    Data migration is the process of transferring data between data storage systems, data formats or computer systems.

  • compact disc (CD)

    A compact disc is a portable storage medium that can be used for recording, storing and playing back audio, video and other data ...

SearchSolidStateStorage

  • NVMe (non-volatile memory express)

    NVMe (non-volatile memory express) is a host controller interface and storage protocol to enable a solid-state drive to use the ...

  • SSD RAID (solid-state drive RAID)

    SSD RAID (solid-state drive RAID) is a methodology commonly used to protect data by distributing redundant data blocks across ...

  • Tier 0

    Tier 0 (tier zero) is a level of data storage that is faster, and perhaps more expensive, than any other level in the storage ...

SearchCloudStorage

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

  • Zadara VPSA and ZIOS

    Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close