Devices Which Switch Faster Than 200 Hz
- Computers and other digital electronic equipment. These devices create and use signals which are switched on/off at great speed. It is the case that any repetitive signal can be reduced down to a Fourier series of sine waves. It so happens that a perfect square wave is
E = Eo sin (ωt) - {Eo sin (2ωt)}/2 + {Eo sin (3ωt)}/3 ......
As the term goes on for ever to higher and higher frequencies the square wave contains harmonics of the fundamental which go on upwards in frequency for ever, these harmonics are responsible for much of the interference created by computers. Always remember that a modern PC is a device which is operating in the VHF/UHF using square waves. As the cases on many computers are not perfect shields, some of this radio frequency energy can leak out and cause interference to radio (and sometimes TV) reception.
- Switch mode power packs can be a source of interference. These are used in consumer electronic/electrical products and in some lighting systems.
Read more about this topic: Television Interference
Famous quotes containing the words devices, switch and/or faster:
“The gods being always close to men perceive those who afflict others with unjust devices and do not fear the wrath of heaven.”
—Hesiod (c. 8th century B.C.)
“Uncritical semantics is the myth of a museum in which the exhibits are meanings and the words are labels. To switch languages is to change the labels.”
—Willard Van Orman Quine (b. 1908)
“When the precipitancy of a man’s wishes hurries on his ideas ninety times faster than the vehicle he rides in—woe be to truth!”
—Laurence Sterne (1713–1768)