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:
“Soon silence will have passed into legend. Man has turned his back on silence. Day after day he invents machines and devices that increase noise and distract humanity from the essence of life, contemplation, meditation.... Tooting, howling, screeching, booming, crashing, whistling, grinding, and trilling bolster his ego. His anxiety subsides. His inhuman void spreads monstrously like a gray vegetation.”
—Jean Arp (1887–1948)
“Children ... after a certain age do not welcome parental advice. Occasionally, they may listen to another adult, which is why perhaps people should switch children with their neighbors and friends for a while in the teen years!”
—Marian Wright Edelman (20th century)
““If everybody minded their own business,” the Duchess said in a hoarse growl, “the world would go round a deal faster than it does.””
—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)