How radio waves are transmitted?

Answer 1

In a radio station, the signals start out at a low-level. On the order of a few hundred millivolts, signals come from a computer's soundcard, or a CD player, nowdays it is almost guaranteed to be some Digital-to-Analog Converter (DAC). These signals are fed into a mixer, where they are combined with other similar signals, and those from the DJ's microphones (also very low level, but amplified first by a Mic pre-amp). The final mix from the mixer is then fed to a RF modulator/amplifier. Here, the signal is first modulated. That is, it is combined with a carrier signal. For example 100.5 FM starts with a 100.5 MHz sinewave. Then it is frequency-modulated by the audio signals from the mixer. In FM, the input signal (audio) causes instantaneous variations in the frequency of the carrier. See the FM Modulation link. Modulation is necessary to carry the signal through the air. Audio waves (20Hz - 20kHz) have such a large wavelength that they would require unbelievably large antennas to broadcast/receive. This modulated signal is then amplified from several mW (.001 Watt) to several kW (1,000 Watts). Then it is carried to the antenna on the radio tower, where it is transmitted through the air.

Answer 2

Radio use radio waves (one with largest wavelength).

Radio station broadcast its program via FM or AM frequency and antennas pick up the signal and when we turn our radio knob to particular frequency we are resonating to the broadcast frequency and as a result we are able to hear our favorite program over the radio.

FM = frequency modulation

AM = amplitude modulation

Answer 3

UV radiation from the sun creates layers of ionized atoms. (atoms that have gained or lost electrons). These electrically charged layers are called the ionosphere. Radio waves travel faster through ionized parts of the atmosphere than non-ionized parts. This is called refraction. Medium wave radio uses wavelengths of about 300m. These radio waves are refracted most in the ionosphere - they are effectively bounced back to Earth. This means that medium wave radio signals can be received a long way from the transmitter.

Answer 4

The universe is filled with a fluid like substance so thin than when an electron moves it creates a wave or ripple.

The transmitter sends back and forth a charge (group of electrons) on a wire (antenna) at a certain frequency and amplitude(with a signal embedded like music) creating waves on the fluid. A radio receiver picks only the waves that you select on your dial and converts the waves into electrical signals and then into sound.

Answer 5

Refraction

UV radiation from the sun creates layers of ionized atoms. (atoms that have gained or lost electrons). These electrically charged layers are called the ionosphere. Radio waves travel faster through ionized parts of the atmosphere than non-ionized parts. This is called refraction.

Answer 6

A broadcasting radio station has to generate and transmit (send out) carrier signals from its transmitters. A carrier signal has to be used because it is impractical to send out sound waves of energy over the very long distances used for radio broadcasting.

If, for example, a station broadcasts on a radio frequency of 455 kHz, before it is transmitted by the station's radio transmitters, that carrier signal first has to be modulated with the sounds coming from the station's studio.

The modulation method used can be either amplitude modulation (AM), frequency modulation (FM) or digital (DAB). DAB is short for "digital audio broadcasting".

At the radio receivers used by the station's listeners, the modulated carrier signal is received through their aerials and then has to be de-modulated to release the studio sound.

De-modulation can be described very simply as "removing the carrier signal to produce the sound".

That sound then has to be amplified so that it can be listened-to using loudspeakers or headphones.

The actual carrier frequencies used by a particular station have to be varied:

1) to suit their transmitters' locations

2) to suit the areas to be covered by that station's broadcasts and

3) to avoid causing interference with other radio stations.

In every country there is a government agency which controls the particular frequencies which can be used by each station that broadcasts in that country.

The fair use of all the frequencies available for broadcasting worldwide is co-ordinated and administered by part of the United Nations organisation - the ITU (International Telecommunications Union) - and its members are representatives from all countries worldwide.

Answer 7

Radio is the wireless transmission of signals through free space by electromagnetic radiation of a frequency significantly below that of visible light, in the radio frequency range, from about 3 kHz to 300 GHz.These waves are called radio wave. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space.

for example

if we speak the wave signal->transducer->electronic signal->electronic processors->transmitter->electronic magnetic wave->receiver->electronic signal->transducer->wave signal->to ear

Answer 8

Radio signals are electromagnetic radiation. Make electric current flow rapidly back and forth in an antenna wire causes electromagnetic radiation to be transmitted from that antenna. As the electromagnetic radiation passes over another antenna wire it causes an electric current to flow in that antenna that is identical to the original current in the transmitting antenna (but weaker) causing the signal to be received.

To transmit and receive information (e.g. Morse Code, voices, music) the transmitting antenna's back and forth electric current must be modulated in some way by that information and the receiving antenna's back and forth current must be demodulated to recover the information. There are many different types of modulation systems that can be used (e.g. continuous wave, amplitude modulation, frequency modulation, phase modulation, single sideband, suppressed carrier, pulse width modulation, pulse time modulation, pulse code modulation).

Many different stations can transmit at the same time and you can select which of these to receive because the transmitters operate on different frequencies of how fast the electric current flow switches direction of flow and your receiver uses an electronic filter that passes only the modulated frequencies of the station you select and block others.