In AM broadcasting, the amplitude of the carrier wave is modulated to encode the original sound. In FM broadcasting, the frequency of the carrier wave is modulated to encode the sound. A radio receiver extracts the original program sound from the modulated radio signal and reproduces the sound in a loudspeaker.
How do AM and FM radio waves compare?
The main difference between AM and FM radio waves is that AM waves are amplitude modulated while FM waves are frequency modulated. AM waves are older and have a larger range, while FM waves have a smaller range but provide better sound quality.
How does a radio work physics?
Radio works by transmitting and receiving electromagnetic waves. The radio signal is an electronic current moving back and forth very quickly. A transmitter radiates this field outward via an antenna; a receiver then picks up the field and translates it to the sounds heard through the radio.
What is meant by AM and FM in physics?
In AM, a radio wave known as the “carrier” or “carrier wave” is modulated in amplitude by the signal that is to be transmitted. The frequency and phase remain the same. In FM, a radio wave known as the “carrier” or “carrier wave” is modulated in frequency by the signal that is to be transmitted.
Why FM is more immune to noise?
During modulating process, the noise gets amplitude modulated. Since it brings about variations only in the amplitude of carrier waves, it does no harm to the message signal. For this reason, FM signal is less susceptible to noise than an AM signal.
How do AM radio waves work?
Receiving an AM Signal The DJ’s voice is modulated onto that carrier wave by varying the amplitude of the transmitter’s sine wave. An amplifier amplifies the signal to something like 50,000 watts for a large AM station. Then the antenna sends the radio waves out into space.
Why do AM waves travel farther than FM?
AM broadcasts use longer wavelength radio waves than FM broadcasts. Because of their longer wavelengths, AM waves reflect off a layer of the upper atmosphere called the ionosphere. You can see how this happens in the Figure below.
Which travels further AM or FM?
FM transmission has broadcast waves ( 88-108 MHZ) that are shorter than AM broadcast waves (540 – 1600 kHz) and do not go as far.
Why is FM radio better than AM?
Each FM station is allocated 150 kHz of bandwidth, which is 15 times that of an AM station. This means that an FM station can transmit 15 times as much information as an AM station and explains why music sounds so much better on FM.
What type of EM waves is FM radio?
FM radio waves: These are the waves that carry radio signals between 88 and 108 MHz. The waves carried are commercial waves where the frequency is modulated while the amplitude remains constant.
Is FM radio analog or digital?
Both analog and digital radios send signals over a radio channel using a Very High Frequency (VHF) or Ultra High Frequency (UHF) carrier frequency wave. In simple terms, analog radios use frequency modulation (FM) to encode a voice signal within a carrier wave.
How do radio waves carry sound?
You can tune a radio to a specific wavelength—or frequency—and listen to your favorite music. The radio “receives” these electromagnetic radio waves and converts them to mechanical vibrations in the speaker to create the sound waves you can hear.
Where is AM and FM used?
Answer: FM is used for voice signal modulation and AM is used for video signal modulation. Answer: We use AM for video signals like TV & for motion picture.FM use for audio signals like radio & for voice signals.
What does AM stand for physics?
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal.
What is the wavelength of AM radio waves?
A 1,000 kHz radio wave has a wavelength of (2.998 × 108 m/s)/(1.000 × 106/s) = 299.8 m. An AM radio wave consists of a sinusoidal carrier wave, which is modulated by an audio signal.
What advantage does FM have over AM?
Detailed Solution. Advantages of FM over AM are: Improved signal to noise ratio (about 25dB) w.r.t. to manmade interference. Smaller geographical interference between neighboring stations.
What are the limitations of FM?
Limitations of FM
(i) FM requires a much wider channel
(ii) FM transmitters and receivers are more complex and costly (iii) In FM reception, less area is covered compared to AM.
What is frequency deviation in FM?
Frequency deviation in FM is defined as the way to describe the difference between the minimum and maximum extent of a frequency modulated signal and the carrier frequency.
Why do AM stations power down at night?
Most AM radio stations are required by the FCC’s rules to reduce their power or cease operating at night in order to avoid interference to other AM stations. FCC rules governing the daytime and nighttime operation of AM radio stations are a consequence of the laws of physics.
What frequencies are AM radio?
The AM band in the United States covers frequencies from 540 kHz up to 1700 kHz, in 10 kHz steps (540, 550, 560 … 1680, 1690, 1700).
What frequency does FM radio use?
FM radio uses frequency modulation, of course. The frequency band for FM radio is about 88 to 108 MHz. The information signal is music and voice which falls in the audio spectrum. The full audio spectrum ranges form 20 to 20,000 Hz, but FM radio limits the upper modulating frequency to 15 kHz (cf.
Why FM is not used for long distance communication?
FM is not a directional signal and you are going so fast and passing over so many antennas you are going to be getting a lot of cross talk and noise. A commercial FM radio designed for radio stations will not be able to make sense out of that signal. Which will travel long distance, AM or FM?
Why does FM signal fade in and out?
The FM signal travels in a straight line and loses strength when it can’t be broadcast straight to the antenna; for example, when blocked by buildings, hills, or large trucks. This causes increased hiss or fading and interruption in the FM signal.
Why is radio clearer at night?
The composition of the ionosphere at night is different than during the day because of the presence or absence of the sun. You can pick up some radio stations better at night because the reflection characteristics of the ionosphere are better at night.
Why is AM radio still used?
Reliable and comforting. There are over 6,000 AM stations in the U.S. today. And they still have a huge audience of listeners, typically locals who seek out the latest weather, traffic, and news information.