Very High Frequency
Very high frequency (VHF) is the ITU-designated range of radio frequency electromagnetic waves from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).
These names referring to frequency usage originate from the early 20th century, when regular radio service used the terms LF (low frequencies), MF (medium frequencies), and HF (high frequencies). These names were standardized by the International Telecommunications Union (ITU) and extended to higher frequency ranges.
Common uses for VHF are FM radio broadcasting, television broadcasting, land mobile stations (emergency, business, private use and military), long range data communication up to several tens of kilometres with radio modems, amateur radio and marine communications. Air traffic control communications and air navigation systems (e.g. VOR, DME & ILS) work at distances of 100 kilometres or more to aircraft at cruising altitude.
Read more about Very High Frequency: Propagation Characteristics, Line-of-sight Calculation, Universal Use, Unlicensed Operation
Famous quotes containing the words high and/or frequency:
“A novel is a mirror carried along a high road. At one moment it reflects to your vision the azure skies at another the mire of the puddles at your feet. And the man who carries this mirror in his pack will be accused by you of being immoral! His mirror shews [sic] the mire, and you blame the mirror! Rather blame that high road upon which the puddle lies, still more the inspector of roads who allows the water to gather and the puddle to form.”
—Stendhal [Marie Henri Beyle] (1783–1842)
“The frequency of personal questions grows in direct proportion to your increasing girth. . . . No one would ask a man such a personally invasive question as “Is your wife having natural childbirth or is she planning to be knocked out?” But someone might ask that of you. No matter how much you wish for privacy, your pregnancy is a public event to which everyone feels invited.”
—Jean Marzollo (20th century)