Matches in DBpedia 2014 for { <http://dbpedia.org/resource/Super_low_frequency> ?p ?o. }
Showing items 1 to 29 of
29
with 100 items per page.
- Super_low_frequency abstract "Super low frequency (SLF) refers to electromagnetic waves (radio waves) in the frequency range between 30 hertz and 300 hertz. They have corresponding wavelengths of 10,000 to 1,000 kilometers. This frequency range includes the frequencies of AC power grids (50 hertz and 60 hertz). Another conflicting designation which includes this frequency range is Extremely Low Frequency (ELF), which in some contexts refers to all frequencies up to 300 hertz.Because of the extreme difficulty of building transmitters that can generate such long waves, frequencies in this range have been used in very few manmade communication systems. However, SLF waves can penetrate seawater to a depth of hundreds of meters. Therefore in recent decades the U.S. and Russian military have built huge radio transmitters using SLF frequencies to communicate with their submarines, with India being in the process of constructing one to be commissioned by 2015. The U.S. naval service is called Seafarer and operates at 76 hertz. It became operational in 1989 but was discontinued in 2004 due to advances in VLF communication systems. The Russian service is called ZEVS and operates at 82 hertz.The requirements for receivers at SLF frequencies is less stringent than transmitters, because the signal strength (set by atmospheric noise) is far above the noise floor of the receiver, so small, inefficient antennas can be used. Radio amateurs have received signals in this range using simple receivers built around personal computers, with coil or loop antennas connected to the PCs sound card. Signals are analysed by a software fast Fourier transform algorithm and converted into audible sound.".
- Super_low_frequency wikiPageExternalLink inspire.html.
- Super_low_frequency wikiPageExternalLink bands.html.
- Super_low_frequency wikiPageID "887767".
- Super_low_frequency wikiPageRevisionID "598540593".
- Super_low_frequency freq "30".
- Super_low_frequency wave "10000".
- Super_low_frequency subject Category:Radio_spectrum.
- Super_low_frequency comment "Super low frequency (SLF) refers to electromagnetic waves (radio waves) in the frequency range between 30 hertz and 300 hertz. They have corresponding wavelengths of 10,000 to 1,000 kilometers. This frequency range includes the frequencies of AC power grids (50 hertz and 60 hertz).".
- Super_low_frequency label "SLF".
- Super_low_frequency label "Super baja frecuencia".
- Super_low_frequency label "Super basse fréquence".
- Super_low_frequency label "Super low frequency".
- Super_low_frequency label "Super low frequency".
- Super_low_frequency label "Super low frequency".
- Super_low_frequency label "Super low frequency".
- Super_low_frequency label "超低頻".
- Super_low_frequency sameAs Super_baja_frecuencia.
- Super_low_frequency sameAs Super_basse_fréquence.
- Super_low_frequency sameAs Frekuensi_super_rendah.
- Super_low_frequency sameAs Super_low_frequency.
- Super_low_frequency sameAs Super_low_frequency.
- Super_low_frequency sameAs SLF.
- Super_low_frequency sameAs Super_low_frequency.
- Super_low_frequency sameAs m.03ly8f.
- Super_low_frequency sameAs Q621063.
- Super_low_frequency sameAs Q621063.
- Super_low_frequency wasDerivedFrom Super_low_frequency?oldid=598540593.
- Super_low_frequency isPrimaryTopicOf Super_low_frequency.