LECTURE NOTES 4 CHAPTER 4: FREQUENCY MODULATION Subtopic: 4-1 Introduction to Frequency Modulation 4-2 Frequency Analysis of the FM wave 4-3 Modulation Index 4-4 Bandwidth Requirements for FM 4-1 INTRODUCTION TO FREQUENCY MODULATION A major problem in AM is its susceptibility to noise superimposed on the modulated carrier signal. This modulation technique is used, for example, in radio transmission and magnetic tape-recording systems. When f = 75 kHz and fi = 200 Hz, then B.W = 2 [75 + (200/1000)] = 150.4 kHz. The last two are combined as Angle Modulation 6. The carrier frequency, fc, should be larger than the highest spectral component . f = Frequency deviation mf = Modulation Index of FM mf = f/fm mf is called the modulation index of frequency modulation. In continuous-wave modulation, a high frequency sine wave is used as a carrier wave. How Frequency modulation Generates 5. The First Frequency Modulation was invented by Edwin Howard Armstrong in December-18-1890 4. RF oscillator produces the carrier signal. The drawback . Single Tone Frequency Modulation. Hence, m (t) is usually considered as a 'single tone modulating signal' of the form . First, pick a center (carrier) frequency. Amplitude Modulation, AM Frequency Modulation, FM Double and Single Sideband, DSB and SSB Digital Modulation Phase Shift Keying: BPSK, QPSK, MSK Frequency Shift Keying, FSK Quadrature Amplitude Modulation, QAM . Modulation is the addition of information to an electronic or optical carrier signal. Frequency modulation, or FM, encodes an information signal by varying the instantaneous frequency of a carrier wave. The FM modulated signal produces an infinite number of sidebands resulting in infinite bandwidth. Modulation l Frequency Modulation (FM) l Most popular analog modulation technique l Amplitude of the carrier signal is kept constant (constant envelope signal), the frequency of carrier is changed according to the amplitude of the modulating message signal; Hence info is carried in the phase or frequency of the carrier. Frequency Shift Keying: The output of a FSK modulated wave is high in frequency for a binary HIGH input and is low in frequency for a binary LOW input. FM Signal for Message m(t) The instantaneous frequency of . Note - FM, as implicit in the above equation for vs (t), is a non-linear process - i.e. Frequency Modulation is the process in which the frequency of the carrier signal is varied by the modulating signal while the amplitude remains constant. Frequency Modulation : Frequency Modulation is a modulation in which the frequency of the carrier wave changes according to the instantaneous amplitude of the modulating signal keeping phase and amplitude constant. It is developed by Edwin H. Armstrong, an American electrical engineer. RL equalizer is shown in Figure 5-17. This is further divided into frequency and phase modulation. Frequency Modulation: The frequency modulation technique is used in computing, radio broadcasting, single processing, telecommunications. The resulting low-frequency output of the lock-in is again demodulated by another phase-sensitive lock-in. Double Sideband Suppressed Carrier (DSBSC): This is the same as the AM modulation . Unlike for noise carriers, the detectability of AM did not decrease with increasing modulation frequency, but was relatively independent of the modulation frequency over a wide range of . It is a modulation in which the amplitude of the carrier wave is changes according to the instantaneous amplitude of the modulating signal keeping phase and frequency as constant. Frequency Modulation . Frequency modulation (FM) is a technique used to encode data on an alternating digital or analog signal. m (t) = A m cos (mt + ) Where, m (t) is the modulating signal. Frequency modulation is the encoding of data in a carrier wave by changing the immediate frequency of the wave. As a result, the effective time constant of the system is 200 s and the LMR sensitivity increases considerably. To be clear, let's go with the below examples. Share This Post: You May Also Like. The primary 4 categories of the mechanism of Modulations are: Analogue modulation. Principles of amplitude and frequency modulation encoding in auditory cortex. In fact, all radio channels in the AM band use this type of modulation. Since Generation of Frequency Modulation is the requirement, the modulating voltage will have to be equalized before it enters the balanced modulator (remember that PM may be changed into FM by prior bass boosting of the modulation). The carrier signal is a sine wave at the carrier frequency. Frequency modulation is the process by which the frequency of the carrier signal changes with respect to the modulating frequency. Below equation shows that the sine wave has three characteristics that can be altered. Angle Modulation is the process in which the frequency or the phase of the carrier varies according to the message signal. Instantaneous Frequency The instantaneousfrequencyof cos(t) is (t) = d dt (t) (1) Motivational Example Let (t) = ct. The mapping of a series of input binary digits into a set of corresponding high-frequency signal waveforms is referred to as digital modulation. In this modulation the frequency of the carrier signal is altered in proportion to the message signal while the phase and amplitude are kept constant is called frequency modulation. As with all assignments within amateur bands, the actual frequency used on any particular occasion is +/- QRM. 11/4/2006 L Lecture 9 Fall 2006 2 Coherent Detection Requires receiver local oscillator to be accurately aligned in phase and frequency to carrier sine wave 2cos(2f ot) y(t) 2cos(2f ot) z(t . A carrier signal is one with a steady waveform -- constant height (amplitude) and frequency. Therefore, x (t) = E m cos (2f m t) The unmodulated carrier is represented by the expression : e c = E c sin ( c t + ) This list is derived from the WIA bandplan as at June 2004. Therefore, x (t) = E m cos (2f m t) The unmodulated carrier is represented by the expression : e c = E c sin ( c t + ) l Has better noise immunity: atmospheric or impulse noise cause rapid . To be clear, let's go with the below examples. The basis for switching a signal with a network signal at different frequencies but with the same amplitude, even if the frequency signal is normal, can be done. The input is a single tone sine wave. Unless the modulation frequency is increased, the bandwidth is not increased and remains constant. equal to the transmitter frequency. A simple. It has various advantages over amplitude modulation and phase modulation. 5.3. Frequency Modulation is the process of varying the frequency . The detection of frequency modulation (FM) and amplitude modulation (AM) was studied for pure-tone carriers of 1 and 4 kHz in the European starling using a Go/Nogo procedure and the method of constant stimuli. To improve on this, the first frequency modulation (FM) radio . Angle Modulation. The resulting low-frequency output of the lock-in is again demodulated by another phase-sensitive lock-in. The term DM stands for digital modulation, and it is a common term for the techniques of modulation. The document Angle modulation and demodulation Notes - GATE is a part of GATE category. The Basics Of Frequency Modulation June 26, 2014 by Adam Fabio 6 Comments [brmarcum] takes us back to analog building block basics with his Frequency Modulation and Demodulation tutorial. Pulse modulation. Frequency modulation. = carrier wave frequency. Its main advantage is that it is more resistant to additive noise than AM. For the single tone frequency modulation,i.e the modulating signal x (t) be a sinusoidal signal of amplitude E m and frequency f m . Note 1: In frequency modulation (FM), the carrier frequency is called the center frequency. For Bach's Minuet, the minimum frequency is 293.7 Hz (D5) and the maximum frequency is 987.8 Hz (B6). modulation (PM), or Frequency modulation (FM). When f = 75 kHz and fi = 200 Hz, then B.W = 2 [75 + (200/1000)] = 150.4 kHz. In other words in frequency modulation, the frequency, as opposed to the amplitude of the carrier wave, is made to change in relation to the differing amplitude of the modulating signal. Digital Modulation. As a result, the effective time constant of the system is 200 s and the LMR sensitivity increases considerably. prescribed limit. The transmitted signal power all through the transmission stays as constant. Home Physics Notes PPT [Physics Class Notes] on Modulation and Demodulation Pdf for Exam [Physics Class Notes] on Modulation and Demodulation Pdf for Exam. Because of demodulation reasons, the magnitude of m (t) is always kept less than 1 and the frequency . FSK is a scheme of frequency modulation. Types of Modulation. Notes and Video Materials for Engineering in Electronics, Communications and Computer Science subjects are added. Frequency Modulation(FM) FM was invented and commercialized after AM. The method includes varying the frequency of the carrier wave on which useful information is imposed or impressed upon. It cannot transmit over long distances, have a smaller range. Frequency Modulation Generation . In amplitude modulation, the . Note that frequencies other than these are also used, particularly for permanent repeaters and packet use where multiple packet channels are required. Usually the transmitter operates on assigned. Frequency Modulation(FM) is the modulation technique in which carrier frequency varies based on analog baseband information signal to be transmitted using wireless device. The carrier and the FM waveforms also are shown in the following figure. Its modulation index varies from 0 to 1. Centre for Telecommunications Value-Chain Research Frequency Modulation Dr. Hwee-Pink Tan http://www.cs.tcd.ie/HweePink.Tan Centre for Telecommunications Value-Chain Research Outline Day 1 Angle Modulation Frequency Modulation (FM) Angle modulation (FM/PM): Importance of FM/PM: An important feature of FM and PM is that they can provide much better protection to the message against the channel noise as compared to the linear (amplitude) modulation schemes. The drawback . The instantaneous fre-quency of s(t) = cosct is d dt ct = c. Frequency . Note that the best peak-to-peak amplitude of the low-frequency modulation is equal to the spectral line width. The carrier frequency is. 1. In Generation of Frequency Modulation broadcasting, L= R at . Start by finding the maximum and minimum frequency values of the notes. An AM signal has the mathematical form s(t) = Ac[1+kam(t)]cosct where m(t) is the basebandmessage. Frequency demodulation is an essential process in telecommunication engineering. PM and digital modulation [] [] s p where 2 is the pk-pk phase change in one symbol duration, T For Digital signals the modulation index: FM signals have the same peak frequency deviation, then when m(t) is a sinusoidal signal set such that the PM and note: phase modulation index peakphasedeviation phase deviation . In this case B m= f m, and a(t) = Z t 1 m(u)du= 1 2f m sin(2f mt) assuming a(1 ) = 0. Frequency Modulation. It involves converting a signal from one frequency to another frequency. Thus, if m(t) is the message signal and c(t)=Acosw c t then FM signal will be . Types of Modulation. In frequency modulation, the amplitude of the signal is constant but the frequency is modified according to signals being sent. As . The detection of frequency modulation (FM) and amplitude modulation (AM) was studied for pure-tone carriers of 1 and 4 kHz in the European starling using a Go/Nogo procedure and the method of constant stimuli. Thus, modulation is required to increase the frequency of the message signal and to enhance its strength to reach the receiver. Note 2: Frequency modulation (FM) and phase modulation (PM) are forms of angle modulation (AM). It operates in the VHF (Very High Frequency) range and can travel long distances. Crystal provides the. Information can be added to the carrier by varying its amplitude , frequency , phase , polarization (for optical signals), and even quantum-level phenomena like spin . The transmitted signal power all through the transmission stays as constant. For the single tone frequency modulation,i.e the modulating signal x (t) be a sinusoidal signal of amplitude E m and frequency f m . Frequency modulation is considered to be superior compare to the Amplitude modulation due to better noise immunity and its ability to reject the interfering signals due to the capture effect. An analogue modulation scheme has an input wave that continuously changes like a sine . frequency modulation (FM) Form of radio transmission.It is the variation of the frequency of a transmitted radio carrier wave by the signal being broadcast. The signal on which data is imposed is known as the carrier signal and the resulting signal with variable frequency is . modulation systems: AM/SSB/DSB Definitions: Deviation, WBFM, NBFM Very popular for VHF voice 10/14/08 2 Definition of an FM Signal For a baseband signal, x(t): - k f is the frequency deviation constant in Hz/volt - A constant envelope signal with varying frequency/phase - The instantaneous frequency is: - Maximum frequency deviation =f= k f |x(t)| max x FM (t)=A c cos2f . FM or Frequency Modulation is a modulation that operates in the region of high frequency and has high bandwidth. Narrow Band FM 2. Digital Modulation Techniques Lecture Notes. lecture notes on FM Lecture material was abstracted from "Communication Systems" by Simon Haykin. It removes communication noise as well as provides enhanced . Frequency Modulation: If the frequency of any carrier wave is varied according to the instantaneous value of a modulating signal, then such a method is known as Frequency modulation. Mathematical representaion . Indifference, both the amplitude modulation and frequency modulation techniques are analog. The technique makes radio reception fairly free from static interference and, although restricted in range to receivers in line-of-sight of the transmitter, has become the most favoured transmission method. frequencies or channels. Frequency Modulation (FM) is an important modulation scheme both because of its widespread commercial use, and because of its simplicity. What do you understand about Digital Modulation. All you need of GATE at this link: GATE. Write down the different types of digital modulation techniques. (A) In radio engineering, modulation is used to encode acoustic stimuli, which can be either amplitude-modulated (AM; upper row) or phase-modulated (PM; second row). Amplitude modulation is implemented by mixing the carrier wave in a nonlinear device with the modulating signal. As we have seen in this document, frequency modulation can be simplified to angle modulation with a simple integrator. The Frequency Modulation is often called FM. The technology is used in telecommunications, radio broadcasting, signal processing, and computing . = wavelength of the transmitted signal. The frequency modulation can be defined as; the frequency of the carrier signal is varied proportional to (in accordance with) the Amplitude of the input modulating signal. is the phase of the modulating signal. Then '^ FM = Aej2fctej sin2fmt where = k f=2f mis frequency deviation ratio . In other words in frequency modulation, the frequency, as opposed to the amplitude of the carrier wave, is made to change in relation to the differing amplitude of the modulating signal. Here, L = length of antenna. F(t)= Acos(w c t+k f m()d) FM Advantage. Note 3:In optical communications systems, even if the electronic . It has several applications. Mechanism of Modulations. to directly vary the frequency of a carrier signal. The Frequency Modulation is often called FM. If the amplitude of the high frequency carrier wave is varied in accordance with the instantaneous amplitude of the modulating signal, then such a technique is called as Amplitude Modulation. Angle Modulation: Angle modulation may be defined as the process in which the total phase angle of a carrier wave is varied in accordance with the instantaneous value of the modulating or message signal while keeping . c(t) = Ac cosct is called the carrierwave. The frequency of the carrier wave is modified in order to send the data or information. The carrier signal is a sine wave at the carrier frequency. Frequency modulation uses the instantaneous amplitude of a modulating signal (voice, music, data, etc.) Frequency Modulation (FM) Definition: A category of angle modulation in which the frequency of the carrier wave is changed according to the amplitude of the message signal is known as frequency modulation. FM has two types, Wideband FM and Narrowband FM. Amplitude Modulation (AM) Block Diagram Time Domain Frequency Domain m x + A c cos w c t x(t) x AM (t)=A c [1+mx(t)]cos w c t X(f) f -f m f m X AM (f) -f c f c Signal information is . Frequency Modulation 6. Instantaneous voltage (E) =E c (max) Sin (2f c t + ) The term that may be varied are the carrier voltage Ec, the carrier frequency fc, and the carrier phase angle . Analog versus Digital Communications . The frequency of the carrier wave is modified in order to send the data or information. The concept was pioneered by Edwin H. Armstrong in the late 1920s and patented in . the principle of superposition does not apply. Modulation and demodulation does . maintain the frequency deviation within the. Modulation mechanisms can also be digital or analogue. This modulation uses discrete signals for modulating a carrier wave. The RF oscillator is stabilized in order to. Combinations of phase and frequency modulation are considered as frequency modulation. May 26 General, Notes 4567 Views No Comments on Frequency Modulation Frequency Modulation Let us consider the baseband signal f(t) and the unmodulated carrier ec(t)=Ecsin(wct+o) As a result, we can generate frequency modulated signals with the National Instruments vector signal generator, because they require . Frequency modulation is the encoding of data in a carrier wave by changing the immediate frequency of the wave. Prerequisite - Modulation 1. Frequency modulation ( FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. Types of Amplitude Modulation (AM) Double Sideband with carrier (we will call it AM): This is the most widely used type of AM modulation. Frequency Modulation : Frequency Modulation is a modulation in which the frequency of the carrier wave changes according to the instantaneous amplitude of the modulating signal keeping phase and amplitude constant. This is further divided into amplitude and angle modulation. Digital modulation. As we know, a modulating signal is the transmitting of information or message after being converted into an electronic signal. 1.6 Spectrum of Frequency Modulated Signal Since frequency modulation is a nonlinear process, an exact description of the spectrum of an frequency-modulated signal for an arbitrary message signal is more complicated than linear process. Next, convert the frequency and duration values into the frequency modulation parameters required by the function generator. LECTURE NOTES 4 CHAPTER 4: FREQUENCY MODULATION Subtopic: 4-1 Introduction to Frequency Modulation 4-2 Frequency Analysis of the FM wave 4-3 Modulation Index 4-4 Bandwidth Requirements for FM 4-1 INTRODUCTION TO FREQUENCY MODULATION A major problem in AM is its susceptibility to noise superimposed on the modulated carrier signal. Angle Modulation - Frequency Modulation ----- Next slide . Frequency modulation (FM) When the frequency of carrier wave is changed in accordance with the intensity of the signal, the process is called frequency modulation. It can transmit over long distances, have a large range. AM is also the abbreviation for amplitude modulation. Thus, there are a few primary modulation mechanisms that we mainly take into practical and usable categorization. 2. Frequency modulation is the process of encoding information on a particular analogue or digital signal by varying the carrier wave frequency in accordance with the frequency of the modulating signal. In frequency modula-tion, the amplitude and phase of the carrier wave remains constant. The other type of modulation in continuous-wave modulation is the Angle Modulation. Phase Shift Keying: Below equation shows that the sine wave has three characteristics that can be altered. It is abbreviated as FM and is a widely used analog modulation technique. Length of the antenna can be easily calculated using this formula: L = = u/. Following is the diagram for FSK modulated waveform along with its input. (B) Proposals for neural AM and PM encoding.A stimulus is made of a frequency-varying signal (upper row) and an amplitude modulation (second row). This produces upper and lower sidebands, which are the sum and difference frequencies of the carrier wave and modulating signal. In Frequency modulation there are two types 1. August 2, 2018 November 12, 2018 Gopal Krishna 0. The frequency of a carrier (fc) will increase as the amplitude of modulating . "A blog to support Electronics, Electrical communication and computer students". Modulation index, , is used to describe the ratio of maximum frequency deviation of the carrier to the maximum frequency deviation of the modulating signal. The binary 1s and 0s are called Mark and Space frequencies. Also, because of their constant amplitude nature, they can withstand nonlinear distortion and amplitude fading. Chapter 5 Amplitude Modulation AM was the rst widespread technique used in commercial radio broadcasting. To improve on this, the first frequency modulation (FM) radio . Though modulation can occur in a number of ways. = (3 x 108) / . Analog I/Q Modulation Time Domain View VwerPailo Frequency Domain View Digital I/Q Modulation Phase Shift Keying Constellations Lecture 9 Analog and Digital I/Q Modulation. enter the un-modulated carrier signal peak Amplitude 1. enter the baseband signal frequency 5. enter the carrier signal frequency 20. enter the frequency Sensitivity 4. enter the duration over which the signal is to be plotted 0.4. enter the sampling frequency 200. Am is the amplitude modulating signal. For example, it is used to modulate the frequency of a signal in FM broadcasting. Frequency Modulation (FM) - NI Toggle navigation Solutions Industries Academic and Research Aerospace, Defense, and Government Electronics Energy Industrial Machinery Semiconductor Spread spectrum method. Fig. The amplitude of the carrier wave is modified in order to send the data or information. Frequency Modulation (FM) is a form of modulation in which changes in the carrier wave frequency correspond directly to changes in the baseband signal. Note that the best peak-to-peak amplitude of the low-frequency modulation is equal to the spectral line width. Instantaneous voltage (E) =E c (max) Sin (2f c t + ) The term that may be varied are the carrier voltage Ec, the carrier frequency fc, and the carrier phase angle . The FM signal for a message m (t) as a band of signals is very complex.