guard frequency

An emergency VHF/UHF (very high frequency/ultrahigh frequency) channel monitored as a secondary frequency by all air and ground stations in a geographical area. The guard frequencies 121.5, 243 and 406 MHz are reserved around the world and are known as international aeronautical emergency frequencies. They should not be used for normal voice messages or general conversation.

Aviation dictionary. 2014.

Look at other dictionaries:

  • Guard band — has several meanings. NOTOC Radio and electronic signallingIn radio, a guard band is an unused part of the radio spectrum between radio bands, for the purpose of preventing interference.It is a narrow frequency range used to separate two wider… …   Wikipedia

  • Guard — may refer to:Professional occupations* Bodyguard, who protects an individual from personal assault * Crossing guard, who stops traffic so pedestrians can cross the street * Prison guard, who supervises prisoners in a prison or jail * Security… …   Wikipedia

  • Guard tone — is a feature of wireline modems.The guard tone is sent by the answering modem after it has sent the answer tone. It is a single continuous tone with a frequency of either 1800 Hz or 550 Hz, sent at a level of 6dB or 3dB, respectively, below the… …   Wikipedia

  • Frequency Division Multiple Access — Multiplexverfahren (lat. multiplex „vielfach, vielfältig“) sind Methoden zur Signal und Nachrichtenübertragung, bei denen mehrere Signale zusammengefasst (gebündelt) und simultan über ein Medium (Leitung, Kabel oder Funkstrecke) übertragen werden …   Deutsch Wikipedia

  • frequency-division multiplexing —    Abbreviated FDM. A method of sharing a transmission channel by dividing the bandwidth into several parallel paths, defined and separated by guard bands of different frequencies designed to minimize interference. All signals are carried… …   Dictionary of networking

  • guard band —    A small frequency band used to separate multiple bands in a broadband transmission and prevent interference between the communications channels …   Dictionary of networking

  • guard band —    The portions of two adjacent frequency bands that remain unused and provide a mutual interference safety margin …   IT glossary of terms, acronyms and abbreviations

  • Aircraft emergency frequency — The aircraft emergency frequency (also known as guard) is a frequency used on the aircraft radio band reserved for emergency communications for aircraft in distress. The frequencies are 121.5 MHz for civilian, also known as International Air… …   Wikipedia

  • Orthogonal frequency-division multiplexing — Passband modulation v · d · e Analog modulation AM · …   Wikipedia

  • Single-frequency network — For other uses, see SFN (disambiguation). A single frequency network or SFN is a broadcast network where several transmitters simultaneously send the same signal over the same frequency channel. Contents 1 Overview 2 OFDM and COFDM 3 DVB T SFN …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.