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Why is amplitude of demodulated FM signal much less than modulated signal?
Wiki User
∙ 10y ago
because demodulated FM is an audio signal, which the frequency is much smaller that is why it can be transmitted alone. It need carrier which has large frequency. Modulated signal is an audio signal + carrier that is why the amplitude is higher.
Wiki User
∙ 10y ago
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Define the bandwidth of a frequency modulated signal?
I believe the bandwidth of ANY signal is defined as the range of frequencies that encompasses 99% of the signal's power. For an AM signal at anything less than 100% modulation, it's 2 x the highest modulating frequency. FM signals aren't that simple to characterize. "Cramer's Rule" says that the bandwidth is 2 x (peak deviation + highest modulating frequency), but as the 'modulation index' increases, that rule becomes a poorer approximation.
Why FM is clearer than am?
The abbreviations FM and AM stands for amplitude modulation and frequency modulation. The reason why FM is more clearer than AM is because FM has a better signal-to-noise ratio than AM does.
What are wavelength frequency time period and amplitude of a sound wave?
Sound waves - which humans and other animals hear through their ears - are actually caused by wave-like variations in pressure travelling through air and other physical media, for example water, wooden doors and floors, etc.Sound travels faster in a less dense medium than it can travel in a more dense medium. The exact speed at which a sound wave travels through a given medium depends on the pressure and temperature of the medium, and therefore on its density.Sound itself is not an electromagnetic (EM) wave but EM waves such as radio signals - and infra-red and visible light transmissions - can fairly easily be "modulated" to carry sound waves as "data". The signals and can then be transmitted through space, air or water.After such signals have been have been received and "demodulated" at radio, infra-red or visible light receivers, the sound can then be heard.Another answerConsidering radio waves, frequencies similar to audible sound are located in the VLF [very low frequency] Radio Band 4 [3 to 30kc/s], known as the myriametric subdivision.The propogation velocity of any radio wave though empty space is 186,282 miles per second, approximately 984 million feet per second. So the wavelength, measured in feet, of a given frequency is approx 984,000 divided by the frequency in kilocycles per second (kHz) or 984 divided by the frequency in megacycles per second (MHz).The propogation velocity of any radio wave through empty space is 300,000,000 meters per second (three hundred million meters per second) so the wavelength, measured in meters, of a given frequency is 300,000 divided by the frequency in kilocycles per second (kHz) OR 300 divided by the frequency in megacycles per second (MHz).Amplitude, which is the signal strength, does not enter into the calculation.
What is gain on guitar amps?
Gain, usually measured in decibels, is the ratio of output to input power. A more sensitive amplifier will have higher gain settings requiring less input signal.
What is gain knob for?
Gain is the INPUT volume of your guitar into the amp, drive select will select different types of distortion (or drive) and drive volume is the OUTPUT volume from the amp. Treble, Middle and Bass are all equalization knobs, turn the bass up for more bass in the signal and same applies with middle and treble or turn then down for less of the frequency in the signal
What does fm and am stand for?
AM-Amplitude modulated FM-Frequency modulated Explanation: The frequency and amplitude refer to the width and height of wavelengths in the radio waves that are used to transmit the signal. FM is usually a better signal than AM because the frequency of the waves is less distorted than amplitude.
How work a DVOR?
The Doppler VOR DVOR is the second generation VOR, providing improved signal quality and accuracy. The REF signal of the DVOR is amplitude modulated, while the VAR signal is frequency modulated. This means that the modulations are opposite as compared to the conventional VORs. The frequency modulated signal is less subject to interference than the amplitude modulated signal and therefore the received signals provide a more accurate bearing determination. The Doppler effect is created by letting the VAR signal be «electronically rotated», on the circular placed aerials, at a speed of 30 revolutions per second. With a diameter of the circle of 13.4 meters, the radial velocity of the VAR signal will be 1264 m/s. This will create a Doppler shift, causing the frequency to increase as the signal is rotated towards the observer and reduce as it rotates away with 30 full cycles of frequency variation per second. This results in an effective FM of 30 Hz. A receiver situated at some distance in the radiation field continuously monitors the transmitter. When certain prescribed deviations are exceeded, either the IDENT is taken off, or the complete transmitter is taken off the air.
Is changing the frequency of the carrier wave to match the amplitude of the signal is called frequency modulation?
more or less, yes
What are the advantages and disadvantages of the 8 qam?
Although QAM appears to increase the efficiency of transmission by utilizing both amplitude and phase variations, it has a number of drawbacks. The first is that it is more susceptible to noise because the states are closer together so that a lower level of noise is needed to move the signal to a different decision point. Receivers for use with phase or frequency modulation are both able to use limiting amplifiers that are able to remove any amplitude noise and thereby improve the noise reliance. This is not the case with QAM. The second limitation is also associated with the amplitude component of the signal. When a phase or frequency modulated signal is amplified in a transmitter, there is no need to use linear amplifiers, whereas when using QAM that contains an amplitude component, linearity must be maintained. Unfortunately linear amplifiers are less efficient and consume more power, and this makes them less attractive for mobile applications.
What is the advantage of sending a pilot carrier with modulated signal?
while demodulating the modulated signal using coherent detection at the receiver end we need to generate the same carrier which is a very difficult ,it makes the receiver costlier and complex because the signal get distorted during the transmission process so generating the same carrier is quite impossible . if we are required to transmit the message to a large number of receivers than it will become very complex and costly. secondly when we modulate and send a pilot carrier it become possible to detect the signal by envelope detection method which requires very less circuitry and is very cheap. provided the sum of maximum amplitude of carrier and the message signal must be greater than zero so that the envelope gets a lift up.. the disadvantage of this scheme is that the higher transmission power is required...
What can you say about the amplitude of a wave that produces a soft sound?
Soft sound means less intense. Intensity is directly proportional to the square of the amplitude. So amplitude will be less for soft sound.
What is disadvantage in amplitude modulation with carrier?
The differeces between frequency and amplitude modulation does not effect the range. Fundamentally the amplitude modulation system is less efficient in that a carrier is generated, which is modulated. The modulation power is half of the carrier power. The bandwidth required is twice the highest modulating fequency. Because of the small bandwidth required, the Amplitude Modulated band on radios is from 550 Khz to 1500 Khz. Channels are separated by 10 Khz, with actual users usually separated by 2 or three channels minimum. Frequency modulation varys the frequency of the carrier by the audio modulating component. While the frequency deviation can be as low as the audio frequency modulating the carrier, better noise performance is achieved by deviating the carrier by as much as possible. In commercial broadcast operations, the 15 Khz audio signal deviated the carrier by 75 Khz. This presents exceptionally good audio reproduction. It also causes the FM (Frequency Modulated) signal to occupy a band of about 240 Khz for a 15 Khz audio channel. This compares to 30 Khz for an equivalent AM (Amplitude modulated) signal. Because of the larger bandwidth required, the FM broadcast band is moved higher in frequency. This makes the other comments about range etc come into effect. AM signals can be received even when an interfering signal is present. Weak signals can be received in the presence of strong signals. Because of this property, Aviation signals, (Airplane to control tower and tower to plane) are in AM. FM signals have an effect called "capture effect" in which a stronger signal will capture the channel and eliminate interference from the weaker signal. Basically you are trading bandwidth for interference rejection. Because of this, signals from satellites, where the signal strength is extremenly small, used to be sent in FM. Present technology uses digital broadcast techniques. Talking about digital, because of the ability of digital receivers to process signals of extremely small size, digital signals are being sent along with both AM and FM broadcast signals for either better quality, or supplementary services. Cell phones are all being switched over to digital technology for better reliability and better channel usage.
Advantages amplitude shift keying?
Amplitude shift keying (ASK) is simple to implement and requires less bandwidth compared to other modulation techniques. It is also less susceptible to noise interference, making it suitable for applications where signal clarity is important. Additionally, ASK is energy efficient as it allows for power conservation by varying amplitude levels.
What is frequensy modulation?
Frequency modulation (FM) is the process whereby the frequency of a radio wave is changed (modulated) rapidly as a result of the changes in the sound that the radio is designed to transmit. In the 'old days' the height of the wave (amplitude) would be modulated to provide a changing signal that could be changed into variable sound by a suitable reciever. This is called amplitude modulation (AM). However, more recently (like 40 years ago) it was found that increasing the frequency to levels known as very high frequency (VHF) and modulating the frequency rather than the amplitude would enable a better quality of transmissions. Also, the higher frequencies meant that radio waves did not travel so far so were less able to interfere with transmissions from other radio stations. The lower the frequency the longer the wavelength and some of the longwave radio transmissions will travel very long distances. The VHF transmissions of today require repeater transmitters located around the country.
What affects absolute brightness?
Brightness corresponds to amplitude of waves. Greater amplitude means greater brightness (so lower amplitude means less brightness).
What affects the size of a wave?
The strength of its creation less losses in its transmission determines the amplitude at any point.ITS AMPLITUDE.
Compare amplitude modulation and frequency modulation?
1)In FM the information signal changes the frequency of the carrier wave without changing its amplitude or phase whereas In AM the information signal changes the amplitude of the carrier wave without changing its frequency or phase.2)All transmitted power in FM is useful whereas in AM most of it is carrier which serves no useful purpose.3)FM has no signal-to-noise (S/N) ratio. It is due to two reasons: firstly, there happens to be less noise at VHF band and Secondly, FM receivers are fitted with amplitude limiters which remove amplitude variation caused by noise, whereas AM has signal-to-noise ratio4)Due to 'guard- band' there is hardly any adjacent-channel interference in FM whereas there is adjacent-channel interference in AM.5)Since only transmitter frequency is modulated in FM, only fraction of a watt of audio power is required to produce 100% modulation as compared to high power required in AM.6)FM requires much wider channel almost up to 20 times as large as needed by AM.7)FM requires complex transmitting and receiving equipment as compared to AM.8)Since FM reception is limited to only line of sight of propagation, area of reception for FM is much smaller as compared to AM.9)FM is used for FM broadcasting & in TV for video signal whereas AM is used for AM broadcasting & in TV for sound signal.10)FM transmission has higher fidelity as compared to AM transmission.
