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Topic: Radio waves


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UHF

  
  Radio - Wikipedia, the free encyclopedia
Radio waves are a form of electromagnetic radiation, created whenever a charged object (e.g., an electron) accelerates with a frequency that lies in the radio frequency (RF) portion of the electromagnetic spectrum.
Radio was used to pass on orders and communications between armies and navies on both sides in World War I; Germany used radio communications for diplomatic messages once its submarine cables were cut by the British.
Radio remote control: Use of radio waves to transmit control data to a remote object as in some early forms of guided missile, some early TV remotes and a range of model boats, cars and aeroplanes.
en.wikipedia.org /wiki/Radio   (4562 words)

  
 Broadcast Signals   (Site not responding. Last check: 2007-10-06)
When information is broadcast from an AM radio station, the electrical image of the sound (taken from a microphone or other program source) is used to modulate the amplitude of the carrier wave transmitted from the broadcast antenna of the radio station.
This is in contrast to FM radio where the signal is used to modulate the frequency of the carrier.
When information is broadcast from an FM radio station, the electrical image of the sound (taken from a microphone or other program source) is used to modulate the frequency of the carrier wave transmitted from the broadcast antenna of the radio station.
hyperphysics.phy-astr.gsu.edu /hbase/audio/bcast.html#c4   (612 words)

  
 Radio
Radio waves are used to transmit the pattern of a heartbeat through a monitor at a patient's home to a nearby hospital.
Radio waves are used in medicine when paramedics are dispatched to the scene where they are needed.
Radio waves from outside the earth are detected using in radio telescopes.
www.smgaels.org /physics/radio_1.htm   (438 words)

  
 Ham Radio and Radio Astronomy
Ships were equipped with radio, huge commercial stations were set up to handle intercontinental messages after the fashion of the telegraph companies, and many other uses were found for the new technology.
Thus, when the first government regulations were imposed on radio in 1912, the amateur operators ("hams"), whose interest in radio was personal and experimental, rather than commercial, got the short end of the stick.
Reber's radio astronomy work continued for a number of years, and his results were published in the Proceedings of the Institute of Radio Engineers, the Astrophysical Journal, Nature, and the Journal of Geophysical research.
www.nrao.edu /whatisra/hist_ham.shtml   (1070 words)

  
 How Things Work - Radio
The radio senses this moving charge and is thus aware of the passing radio wave.
The ideal length of a vertical receiving antenna is a quarter of the wavelength of the radio wave it's trying to receive--in which case, charge that the radio wave's electric field pushes up and down the antenna has just enough time to reach the end of the antenna before it has to reverse directions.
Radio waves consist of nothing more than electric and magnetic fields that are perpetually recreating one another as they travel through space at the speed of light.
howthingswork.virginia.edu /radio.html   (6257 words)

  
 Space Weather   (Site not responding. Last check: 2007-10-06)
Radio transmissions are a combination of two kinds of waves: audio frequency waves that represent the sounds being transmitted and radio frequency waves that "carry" the audio information.
All waves have a wavelength, an amplitude and a frequency as shown in the figure.
Electromagnetic waves (like radio waves) are produced by the spark discharges in car ignition systems, brushes of electric motors and in all sorts of electrical appliances, as well as in thunderstorms.
www.windows.ucar.edu /spaceweather/wave_modulation.html   (326 words)

  
 Radio frequency - Wikipedia, the free encyclopedia
Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna.
The SHF and EHF bands are often considered to be not part of the radio spectrum and form their own microwave spectrum.
Radio and light waves conversion: frequency to wavelength and vice versa
en.wikipedia.org /wiki/Radio_waves   (356 words)

  
 Radio Waves From the Aurora, Alaska Science Forum
The motion of the electrons generates radio waves, which cause the electrons to change their spiraling motion so they are moving more nearly parallel to the magnetic field.
The radio signal is produced by interaction of the auroral electron beam with electrons in the upper ionosphere well above the aurora, at a height of around 3000 kilometers.
The radio waves are emitted to the sides of the beam, rather than along it, so they are more likely to reach the earth when the auroral bands are on the horizon than when they are overhead.
www.gi.alaska.edu /ScienceForum/ASF8/859.html   (668 words)

  
 Radio Waves
Radio waves have the longest wavelengths in the electromagnetic spectrum.
These long waves are in the radio region of the electromagnetic spectrum.
Radio telescopes are dishes made out of conducting metal that reflect radio waves to a focus point.
imagers.gsfc.nasa.gov /ems/radio.html   (566 words)

  
 PROPAGATION OF RADIO WAVES   (Site not responding. Last check: 2007-10-06)
Degree of the curve depends on the angle of incidence of the wave, ionization gradient of the layer and frequency of the signal.
Short wave radio signals (radio signals which fall in the range of 3 to 30 MHz) are reflected from the ionosphere just as light rays are reflected from the surface of a mirror, or sound wave from a barrier.
Radio waves are commonly refracted when they travel through different layers of the atmosphere, whether it is highly charged ionospheric layers 100 km and higher, or weather-sensitive area near the Earth surface.
www.qsl.net /vu2msy/propagation.htm   (3441 words)

  
 How A Crystal Radio Works for Beginners
Radio waves travel across the crystal radio antenna all the time.
Radio waves are invisible waves of electricity and magnetism.
Radio wave electricity is electricity that radio waves make in the antenna wire.
www.midnightscience.com /howxtal.html   (1395 words)

  
 S.O.N. | Radio Waves
Radio waves are especially useful because they can be measured by instruments on the Earth and in interplanetary space.
You will use radio, x-ray and ultraviolet data to tell you when a major solar storm has taken place and where on the Sun that storm occurred.
Ground-based radio observatories provide real-time measurements of radio emissions from the Sun and archives of results from earlier measurements.
son.gsfc.nasa.gov /tass/radiowaves   (318 words)

  
 Radio Waves   (Site not responding. Last check: 2007-10-06)
Waves that travel along the surface of the Earth are called ground waves.
As a result, the top part of a wave front moving at a particular angle into the ionosphere moves faster than the lower part of the wave front, and the entire wave is refracted downward.
The greater height of the F layer means the refracted wave returns to Earth much farther away than the daytime refraction from the lower layers.
members.aol.com /svennord/radio.htm   (473 words)

  
 Electromagnetic Spectrum
Radio waves have photons with low energies, microwaves have a little more energy than radio waves, infrared has still more, then visible, ultraviolet, X-rays, and gamma-rays.
Radio waves CAN make it through the Earth's atmosphere without significant obstacles (In fact radio telescopes can observe even on cloudy days!).
Radio astronomers can combine data from two telescopes that are very far apart and create images which have the same resolution as if they had a single telescope as big as the distance between the two telescopes!
imagine.gsfc.nasa.gov /docs/science/know_l2/emspectrum.html   (2321 words)

  
 The Electromagnetic Spectrum: radio waves   (Site not responding. Last check: 2007-10-06)
Radio waves are made by various types of
They are also given off by stars, sparks and lightning, which is why you hear interference on your radio in a thunderstorm.
Radio waves are the lowest frequencies in the electromagnetic spectrum, and are used mainly for
www.darvill.clara.net /emag/emagradio.htm   (145 words)

  
 The Sun: Microwave and Radio Waves   (Site not responding. Last check: 2007-10-06)
Microwave and radio wave are the names given to light with wavelengths from about 1 millimeter (1 million nanometers) to more than 10 meters.
Radio waves penetrate through the outer layers of solar gas, called the "chromosphere" and
The depth to which the radio waves and microwaves can penetrate depends on their exact wavelength.
solar.physics.montana.edu /YPOP/Spotlight/Today/microwave.html   (201 words)

  
 Reason magazine -- June 1999
This being American radio, the wave of mergers reflects a combination of crude capitalism and crude socialism: People are making a lot of money, but in a way shaped by the state, which has eased restrictions on combinations while making it steadily harder for startup stations to challenge the chains.
Micro radio has a constituency, one that has gathered support from several city councils, a state legislature, at least 28 congressmen, and--in a limited but still astonishing way--from the chairman of the FCC itself.
Stephen Dunifer--founder of Free Radio Berkeley, one of the country's most prominent unlicensed operations--calls the commission's plan a "bogus" scheme "designed to invoke the splitting of the movement to reclaim the airwaves." Others fear that commercial stations will squeeze out the listener-sponsored outlets that currently dominate the unlicensed micro radio community.
www.reason.com /9906/fe.jw.radio.html   (4058 words)

  
 Radio frequency   (Site not responding. Last check: 2007-10-06)
RFI (radio- frequency interference) is a serious EMI threat...
looking at each of the components of a radio frequency system, the antenna serves the same purpose as almost all other radio frequency systems.
Radio and light waves conversion: frequency to wavelength and back
www.hallencyclopedia.com /Radio_frequency   (350 words)

  
 Radio Waves Detected Coming From Center of Galaxy   (Site not responding. Last check: 2007-10-06)
Summary Astronomers have detected unusual, powerful radio waves coming from an unknown source in the direction of the center of our galaxy.
The galaxy is full of objects that emit radio waves, including fl holes and stars of various kinds.
But short-lived radio bursts are rarely detected, because radio telescopes, until recently, have only been able to focus on a relatively small area of the sky in each observation.
news.nationalgeographic.com /news/2005/03/0302_050302_galactic_radio.html   (668 words)

  
 Jove's Thunderbolts
Radio waves from the giant planet Jupiter have been detected by astronomers at the Carnegie Institution in Washington.
The waves appear to be short bursts of static, much like those produced by thunderstorms on conventional radio receivers.
Then radio noises were found arriving from far-away galaxies and were explained as crashes between galaxies riding through one another.
www.varchive.org /bdb/thunderbolts.htm   (940 words)

  
 washingtonpost.com: Radio Waves
Randi Rhodes always gets stage fright before she goes on the air, even after 20-odd years in radio, but this is not her usual pre-show panic; this is different.
A couple of weeks earlier, before the dimensions of the turmoil were clear and true terror set in, Rhodes had confidently explained that in radio as in the Republic, "the pendulum swung all the way to the right, all through the '80s, and it's been like that for 20 years.
Political talk radio seems to function most effectively, moreover, when its audience is out of power and aggrieved about it, when there's a convenient target to attack.
www.washingtonpost.com /ac2/wp-dyn/A3763-2004Sep7?language=printer   (6961 words)

  
 NASA - Eerie Sounds of Saturn's Radio Emissions
The radio waves are closely related to the auroras near the poles of the planet.
The Cassini spacecraft began detecting these radio emissions in April 2002, when Cassini was 374 million kilometers (234 million miles) from the planet, using the Cassini radio and plasma wave science instrument.
The radio and plasma wave science team is based at the University of Iowa, Iowa City.
www.nasa.gov /mission_pages/cassini/multimedia/pia07966.html   (321 words)

  
 Sligo Weekender: Radio Waves   (Site not responding. Last check: 2007-10-06)
Since the advent of internet radio, the world really has become a small place and, as we have discovered, Irish people have made their way to the four corners of the globe.
Radio business at the best of times can be busy and full of surprises.
It’s been a good week for us at the radio station because word has come through from the PPI, which is the Phonographic Performance Society of Ireland that four of our programmes, plus both of our radio stations have been nominated to pick-up awards.
www.sligoweekender.ie /news/radiowaves.asp   (3394 words)

  
 Homepage
Radio Waves is one of the largest independent Motorola dealers in New Zealand.
With the 'premier' stamp of approval and a strong relationship with Motorola Australia we are able to offer our clients world class product and systems through a team of highly experienced and dedicated account managers.
Whether its radio, mobile data, installation, service or rentals, we will listen, understand the requirement and deliver the best and most cost-effective solution, optimising your company's efficiencies and saving $$$.
www.radiowaves.co.nz   (78 words)

  
 Radio Waves - TV & Radio - Entertainment - theage.com.au
THE mainstream youth radio stations on the FM band are a pretty similar bunch.
Recent issues on Hack include cannabis psychosis, young women who survive on the largesse of sugar daddies, pornography's impact on relationships, the potential risks of inhaling the drug nitrous oxide and veganism.
It is fresh, sometimes startling radio that covers current affairs topics from angles never otherwise heard on the ABC, let alone the mainstream commercial radio stations Triple J competes against.
theage.com.au /news/tv--radio/radio-waves/2005/09/27/1127804481313.html   (519 words)

  
 Radio Waves
I have related my story on getting my first radio in the past, but I have to confess that I felt a twinge of sadness to see radios declining in popularity.
Of course, radio programming is probably as strong now as it ever was, and the Internet has made for some fascinating hybrids of radio broadcasting and delivery, so the medium is still quite vibrant.
We had a television when I acquired my radio, but this was before cable was an option where I lived, and the radio was a vastly more exciting medium late at night anyway.
librarycog.uwindsor.ca:8087 /artblog/librarycog/1124200295   (817 words)

  
 The World of NMR: Magnets, Radio Waves, and Detective Work
The researchers then blast the sample with a series of split-second radio wave pulses that disrupt this magnetic equilibrium in the nuclei of selected atoms.
Each NMR experiment is composed of hundreds of radio wave pulses, with each pulse up to a few milliseconds after the previous one.
NMR's radio wave pulses are quite tame compared to the high-energy X-rays used in crystallography.
publications.nigms.nih.gov /structlife/chapter3.html   (2769 words)

  
 History of Radio   (Site not responding. Last check: 2007-10-06)
Edwin Armstrong patented the regenerative circuit in 1913 that fed a radio signal through an audion tube 20,000 times per second to caused stronger oscillations in the tube that generated radio waves.
De Forest began the longest lawsuit in radio history in 1915 when he sued Armstrong over the basic regenerative patent, but lost in 1921 and 1923 when it was demonstrated in court that de Forest could not explain how or why his audion tube oscillated; Armstrong did understand and made a clear explanation of regeneration.
The American Radio Relay League in Dec. 1921 made the first successful transatlantic shortwave broadcasts with small superheterodyne receivers, and Frank Conrad would develop regular commercial shortwave broadcasting.
history.acusd.edu /gen/recording/radio.html   (1217 words)

  
 GNU Radio - GNU FSF Project   (Site not responding. Last check: 2007-10-06)
GNU Radio is a collection of software that when combined with minimal hardware, allows the construction of radios where the actual waveforms transmitted and received are defined by software.
Joe Mitola says, "A software radio is a radio whose channel modulation waveforms are defined in software.
They range from playing a sine wave out a speaker, a single channel FM receiver, a display of the real time Fourier transform of the signals from a high speed analog to digital converter, to an application that receives two broadcast FM stations at the same time from the same input.
www.gnu.org /software/gnuradio   (492 words)

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