Very high frequency
Very high frequency (VHF) is the
radio frequency range from 30
MHz to 300
MHz. It is also known as the meter band or meter wave as the wavelengths range from ten to one
meters. Frequencies immediately below VHF are denoted
HF, and the next higher frequencies are known as
Ultra high frequency (UHF).Common uses for VHF are
FM radio broadcast at 88–108 MHz and
television broadcast (together with
UHF). VHF is also commonly used for terrestrial navigation systems (
VOR in particular), marine communications, and aircraft communications.VHF frequencies' propagation characteristics are ideal for short-distance terrestrial communication, with a range generally somewhat farther than line-of-sight from the transmitter (see formula below). Unlike high frequencies (HF), the ionosphere does not usually reflect VHF radio and thus transmissions are restricted to the local area (and don't interfere with transmissions thousands of kilometres away). VHF is also less affected by atmospheric noise and interference from electrical equipment than low frequencies. Whilst it is more easily blocked by land features than HF and lower frequencies, it is less bothered by buildings and other less substantial objects than higher frequencies.
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Bandes de fréquences de la télévision terrestre
Très haute fréquence
Ultrakurzwelle
Filtr Kalmana
UKF
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Very high frequency
VHF è l'
acronimo di Very High Frequency e sta ad indicare la parte dello spettro delle
onde radio compresa tra 30 e 300
MHzQuesta banda è utilizzata per la maggior parte delle comunicazioni aeronautiche civili, navali, delle forze di polizia e per la trasmissione di alcuni canali televisivi. Le frequenze da 144 a 146 MHz sono riservate all'attività di
radioamatore. La banda compresa tra gli 88 e i 108 MHz è utilizzata per la trasmissione radiofonica in
FM, mentre segnali complessi contenenti tutte le frequenze di questa banda vengono impiegati per la
magnetoterapia ad alta frequenza.
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