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Mathematical expression for side band amplitudes in FM signal?
In frequency modulation (FM), the sideband amplitudes can be expressed using Bessel functions. For an FM signal with a modulation index ( \beta ) (the ratio of the frequency deviation to the modulation frequency), the amplitudes of the sidebands are given by ( J_n(\beta) ), where ( J_n ) is the Bessel function of the first kind of order ( n ). The sideband amplitudes corresponding to the carrier frequency will have values of ( J_n(\beta) ) for ( n = 0, \pm 1, \pm 2, \ldots ). Thus, the total signal can be represented as a sum of these sidebands, modulated around the carrier frequency.
Why we need high power to generate AM signal and low power to generate FM signal?
The reason FM has lower power and AM has higher power is because the more power that an AM signal has, the farther it will go, but FM does not work that way. AM waves can bounce off of the atmosphere, especially at night. This is the reason that you can hear AM stations from far away at night. FM, on the other hand, can't bounce. FM waves only go in a straight line from the tower and no matter how much power you transmit with, an FM wave will only go a short distance. AM Waves can travel through trees and buildings, and FM can't.
Is ferquency modulation a linear modulations?
Frequency modulation (FM) is considered a form of nonlinear modulation. In FM, the frequency of the carrier wave varies in accordance with the amplitude of the input signal, which can lead to a complex relationship between the input and output signals. This nonlinearity is characterized by the generation of sidebands and additional frequency components that are not present in the original signal. Thus, FM does not maintain a direct proportionality between input and output, distinguishing it from linear modulations like amplitude modulation (AM).
What are the frequency components at the output of the modulator?
The frequency components at the output of a modulator typically include the carrier frequency and the sidebands generated by the modulation process. For amplitude modulation (AM), the output contains the carrier frequency along with upper and lower sidebands, which are spaced from the carrier by the modulating frequency. In frequency modulation (FM), the output consists of the carrier frequency and a series of sidebands determined by Bessel functions, reflecting the modulation index. The specific frequencies present depend on the modulation scheme and the characteristics of the input signal.
How do you detect FM signal?
FM signals can be detected using a frequency discriminator or a phase-locked loop (PLL) demodulator. The frequency discriminator converts the frequency variations of the FM signal into amplitude variations, which can then be amplified and filtered to recover the original audio signal. In a PLL, the incoming FM signal is compared to a locally generated signal, allowing for the extraction of the original information by tracking the phase differences. Both methods enable effective retrieval of the modulating audio or data signal from the FM carrier.
What is narrow band FM and how a narrow band FM generate?
If the modulation index of FM is kept under 1, then the FM produced is regarded as narrow band FM. Lower the modulation index, lower the no. of significant sidebands are produced (with reference to bessel function). So lower the no. of significant sideband, lowerer will be the bandwidth of the resulting FM prduced. Sometimes, Narrow Band FM is regarded as, when the significant energy in FM occupies the same bandwidth as ordinary AM with the same modulating signal.
Mathematical expression for side band amplitudes in FM signal?
In frequency modulation (FM), the sideband amplitudes can be expressed using Bessel functions. For an FM signal with a modulation index ( \beta ) (the ratio of the frequency deviation to the modulation frequency), the amplitudes of the sidebands are given by ( J_n(\beta) ), where ( J_n ) is the Bessel function of the first kind of order ( n ). The sideband amplitudes corresponding to the carrier frequency will have values of ( J_n(\beta) ) for ( n = 0, \pm 1, \pm 2, \ldots ). Thus, the total signal can be represented as a sum of these sidebands, modulated around the carrier frequency.
Why we need high power to generate AM signal and low power to generate FM signal?
The reason FM has lower power and AM has higher power is because the more power that an AM signal has, the farther it will go, but FM does not work that way. AM waves can bounce off of the atmosphere, especially at night. This is the reason that you can hear AM stations from far away at night. FM, on the other hand, can't bounce. FM waves only go in a straight line from the tower and no matter how much power you transmit with, an FM wave will only go a short distance. AM Waves can travel through trees and buildings, and FM can't.
Why FM have infinte number of sidebands?
It can't. FM (like broadcast AM) has two *sidebands*, one at a higher frequency than the transmitter's carrier, one at a lower frequency. The modulating signal (voice, music, etc) of any trasnmitter creates one or more pairs of side frequencies within the two sidebands. A broadcast AM signal can only produce two side frequencies, so an AM transmitter at 1.5 MHz, with a 1 kHz modulating tone (fm), would put out its carrier (fc) at 1.5 MHz, a lower side frequncy at (1.5 - 0.001) = 1.499 MHz, then its carrier at 1.5 MHz, and then the upper side frequency at (1.5 + 0.001) = 1.501 MHz. The AM signal can never be wider than twice the highest modulating frequency (fm), spanning from (fc - fm) to (fc + fm), a span of 2 x fm. Be aware that special-purpose AM systems can generate just *one* sideband - we won't go into that amount of detail apart from noting it. FM signals can be wider than twice the highest modulating frequency. The complete analysis needs the mathematical Fourier Transform, but we can think of it this way. Stronger frequency modulation shows up as a larger change in the transmitted signal frequency. An FM signal at 100 MHz, modulated by a 1 KHz tone, *can* put out a lower side frequency at (100 - 0.001) = 99.999 MHz and an upper side frequency at (100 + 0.001) = 100.001 MHz. You could receive this just fine, but it would sound "weak" compared to normal broadcasts. It's possible to increase the frequency shift to (say) five times. Now, the sidebands must extend from (100 - 5x0.001) = 99.995 MHz to (100 + 5x0.001) = 100.005 MHz. How do we account for the original 1 KHz tone creating a bandwidth of 2x5 kHz? The answer is that we actually have *five* lower side frequencies, at -5, -4, -3, -2, -1 kHz below the carrier, and *five* upper side frequencies at +1, +2, +3 +4 and +5 kHz above the carrier. Notice that they are multiples of the original 1 kHz modulating frequency. These can, in fact, be shown on the instrument called a spectrum analyser. Your question? As with broadcast AM, an FM signal has only two sidebands. In FM, the strength of modulation (the modulation index) controls the number of individual side frequencies, and thus the total bandwidth of the signal. Can an FM signal have *infinite* numbers of side frequencies? Not really. It can have a *very large* number of side frequencies with very great modulation strength. In practice, this would take up *a lot* of the FM radio band, so broadcast FM commonly uses a maximum modulation index of 5.0. This means that a fully-modulating 15 kHz signal would give a bandwidth of -(15 x 5) to +(15 x 5) kHz, which is +/- 75 kHz.
Is ferquency modulation a linear modulations?
Frequency modulation (FM) is considered a form of nonlinear modulation. In FM, the frequency of the carrier wave varies in accordance with the amplitude of the input signal, which can lead to a complex relationship between the input and output signals. This nonlinearity is characterized by the generation of sidebands and additional frequency components that are not present in the original signal. Thus, FM does not maintain a direct proportionality between input and output, distinguishing it from linear modulations like amplitude modulation (AM).
What are the frequency components at the output of the modulator?
The frequency components at the output of a modulator typically include the carrier frequency and the sidebands generated by the modulation process. For amplitude modulation (AM), the output contains the carrier frequency along with upper and lower sidebands, which are spaced from the carrier by the modulating frequency. In frequency modulation (FM), the output consists of the carrier frequency and a series of sidebands determined by Bessel functions, reflecting the modulation index. The specific frequencies present depend on the modulation scheme and the characteristics of the input signal.
A modulated waveform that contains a carrier plus two sidebands for each modulation frequency is a description of?
Both AM and narrow-band-FM.
How can a condenser microphone be used to generate FM?
A condenser microphone can generate frequency modulation (FM) by converting sound waves into electrical signals. When sound waves hit the microphone's diaphragm, it causes variations in capacitance, which translates into corresponding voltage changes. These voltage changes can then modulate a carrier frequency in an FM transmitter, effectively encoding the audio signal onto the carrier wave. This process allows the microphone to wirelessly transmit the sound in an FM format.
How do you detect FM signal?
FM signals can be detected using a frequency discriminator or a phase-locked loop (PLL) demodulator. The frequency discriminator converts the frequency variations of the FM signal into amplitude variations, which can then be amplified and filtered to recover the original audio signal. In a PLL, the incoming FM signal is compared to a locally generated signal, allowing for the extraction of the original information by tracking the phase differences. Both methods enable effective retrieval of the modulating audio or data signal from the FM carrier.
Differentiate FM signal from AM signal?
FM = Frequency Modulation; AM = Amplitude Modulation; each being a technique by which the speech signal is imprinted onto the carrier signal (the one to which you tune the radio). FM is a higher frequency than AM. FM also only uses the 2.7hz upper side band of the frequency while AM utilizes the entire 6hz both the LSB, USB and the .6hz carrier wave. That allows AM to travel farther than a FM signal.
Why you convert FM signal to IF frequency?
Mix it with a local oscillator whose frequency is (the IF frequency) away from the frequency of the FM signal you're interested in.
How does a high-power FM transmitter work?
Summary: An FM transmitter has an oscillator that generates the carrier RF signal. Frequency modulation takes place at the oscillator stage. The modulated signal is then sent through some filters and then finally amplified by a class C power amplifier, and then delivered to the antenna. An FM transmitter has an oscillator that generates a carrier signal on a desired frequency. But something like a voltage controlled oscillator is used so that the oscillating frequency can be changed by a modulating signal. When there is no modulation, the oscillator runs at it assigned frequency (called a center frequency). The voltage that is controlling the frequency at which it is running is constant. By applying the volage of a modulating signal to that "controlling" voltage, the frequency of the signal can be caused to vary above and below its assigned center frequency in a way that is directly proportional to the modulating signal. It is shifted above and below its assigned center at a rate proportional to the frequency of the modulating signal and at an amount proportional to the amplitude of the modulating signal. This takes up a bit of what is called bandwidth on the electromagnetic spectrum. The modulated FM signal appears as a "group" of frequencies around that center frequency with the sub-group of frequencies about the center being called the upper sideband, and that sub-group below the center being called the lower sideband. Almost all of the power in the generated signal is carried in these sidebands. This RF signal is them amplified by a high power RF amp, and the (now) high-powered FM signal is then sent via a transmission line to an antenna, from where the signal radiates into space. A link is provided to the Wikipedia article on FM modulation. Surf on over and check out the drawings and the little "moving pictures" to get a handle on FM. (No static at all!)
