Restoring or recovering the message signal from the received modulated waveform that is generally corrupted by noise types of am detectors. To study sampling and reconstruction of pulse amplitude modulation. Students will explore the mathematical theory behind amplitude modulation and use the analog discovery 2 to visualize the effects of amplitude modulation in the time and frequency domains. The goal of this experiment is to become familiar with fm modulation and demodulation. Also, fm transmitterreceiver is indeed an electronic project that places great emphasis on. Sideband dsbsc modulation, frequency modulation and demodulation, pcm coding and encoding, etc. Vary the modulating frequency and amplitude and observe the effects on the modulated waveform. Connections are made for the am modulator and demodulator as shown in the circuit. If it is modulated by a hipolar hit stream according to the scheme illustrated in figure below, its polarity will be reversed every time the bit stream changes polarity. It is still in use today in a variety of systems, including, of course, am broadcast radio. The concepts of amplitude modulation, modulation and demodulation, along with their.
To perform the frequency modulation and demodulation using fm kit. Lab manual frequency modulation experiment 8 experiment 2 objectives. Distinguish between different types of fm signal 4. Cme312 lab manual dsbsc modulation and demodulation experiment 6 experiment 2 part iv. Frequency modulation fm, as well as phase modulation pm, are types of angle exponential modulation. The frequency modulator and demodulator structures are as explained below. Microwave and digital communication lab 1 digital communications lab list of experiments. This, for a sinewave, is equivalent to a phase reversal shift. It is relatively difficult to tune, as tuned circuit must be tuned to different frequency than carrier frequency.
In the context of radio communication, near the end of the 2oth century, few modulated signals contain a significant component at carrier frequency. Ece 4670 communication systems laboratory experiments. It is inefficient, as it is linear in very limited frequency range. Build simple fm demodulator by using frequency discriminator. Vectors and modulation cse 466 interfacing 3 spose m and n are orthogonal unit vectors.
This ic includes the circuits of pcm modulation and demodulation. A minimum of 10ten experiments have to be performed and recorded. The modulated carrier signal is sent to the receiver where demodulation of. Dutton ee3 winter 2004 1 ee3 lab 1 amplitude modulation and demodulation 1 lab notes a word about power. This is a laboratory manual for analog communication experiments. This laboratory exercise introduces frequency modulation. Frequency modulation and frequency demodulation experiment. The technology is used in communication systems such as amateur radio, caller id, and urgent situation broadcasts. Examine the factors affecting the shape of the spectrum and the bandwidth of fm signals.
Feel free to use the lab to practice your skills before the. Frequency modulation fm the process of combining the message. Should take only the lab manual, calculator if needed and a pen or pencil to the work area. Practical approach to frequency modulation and demodulation. Experiment 2 experiment 6 experiment dsb sc modulation. Once the signal has been received, filtered and amplified, it is necessary to recover the original modulation from the carrier. It does not carry much information that we can relate to data or speech. The second is to investigate classical analog amplitude modulation and the envelope detector. The continuous analog signal st is a baseband signal with the information content. By the end of this experiment, the student should be able to. Fm demodulation is a key process in the reception of a frequency modulated signal. Fm modulation and demodulation electrical and computer. In the first model, you are provided a fm structure that is very similar to the theoretical background of this experiment.
Frequency shift keying fsk modulation and demodulation. To study amplitude demodulation by linear diode detector 3. The depth of modulation can be varied using the variable knob provided at a. Carrier modulation allows the transmission of modulating frequencies without the use of transmission wire as a medium. It is this process that is called demodulation or detection. Build simple envelope detector for fm demodulation. Fm is considered an analog form of modulation because the baseband signal is typically an analog waveform without discrete, digital values. Frequency modulation 1 objective to understand the principles of frequency modulation and demodulation. To study frequency modulation and determine its modulation factor. Pcs lab manual page 1 laboratory manual principles of communication system lab ee226f ivth semester prepared by.
However if st is sinusoidal, then the instantaneous frequency deviation of the anglemodulated signal is. Then, students will use labview to program an am demodulator and use it to explore and visualize the. Ece 4670 communication systems laboratory experiments manual spring 2010 mark a. Pcs lab manual page 1 laboratory manual principles of communication system lab ee226f. Using matlab mfile and simulink to implement fm modulation and demodulation. Frequency modulation and demodulation experiment tutorial by mr. Experiment 2 experiment 6 experiment dsb sc modulation and. Introduction in chapters 1 and 2 you studied how to apply intelligence modulation to an rfcarrier wave.
The frequency of a radiofrequency channel can be explained best as the frequency of a carrier wave. Then inner products dot products are 1 1 0 can interpret inner product as projection of vector 1 v1 onto vector 2 v2in other words, inner product of v1 and v2 tells us how much of vector 1 is there in the direction of vector 2. A carrier wave is purely made up of constant frequency, slightly similar to a sine wave. To study and perform pulse width modulation and demodulation. To study and perform frequency modulation and demodulation. Matlab, time and frequency domain representation of signals, and processing of speech signals. Nov 21, 2017 frequency modulation and demodulation experiment tutorial by mr. It reacts to all amplitude changes needs a limiter. Frequency modulation fm is a form of modulation in which changes in the carrier wave frequency correspond directly to changes in the baseband signal.
Digital phase modulation and demodulation request pdf. The frequency of the carrier remains constant frequency modulation fm frequency modulation is the process of varying the frequency of a carrier wave in proportion to the amplitude of a baseband signal. Describe phase demodulation circuit operation for the peak, lowpass filter, and conversion detectors. In singlechannel efield sensing, the carrier we transmit is m, the sensed value is a, and the noise is n vectors. Frequency modulation fm is a process in which the carrier frequency is varied by the amplitude of the modulating signal i. Effect of frequency mismatch of course, no one is interested in making. The signal at pin 7 of the 565 contains some carrier frequency in addition to the ac and dc levels just discussed. Frequency discrimination slope detector major limitations.
An envelope detector is a simple and yet highly effective device that is well suited for the demodulation of am wave, for which the percentage modulation is less then 100%. The demodulation circuit is used to recover the message signal from the incoming am wave at the receiver. Frequencyshift keying fsk is the frequency modulation system in which digital information is transmitted through the discrete frequency change of a carrier wave. Analog communication lab manual, prepared by nakka. In this experiment, we use ic cw6694 from conwise to implement the pcm modulator. Note that this is on the very low end of the recommended voltage range.
If you have the time, take a look at the theory behind phaselocked loops pll, as in pp. The percentage modulation can be calculated using the formula. Equation 2 shows that the product is represented by two new signals, one on the sum frequency. Ece 4670 communication systems laboratory experiments manual. The process and the signal were called amplitude modulation, or am for short. Demonstrate understanding of frequency modulation and demodulation technique. Prof mist mist, hyderabad ece department page 8 physitechs modulation and demodulation trainer has a carrier generator, which generates carrier wave of 100khz when the trainer is switched on. Transmitter and receiver are simple in amplitude modulation. This lab introduces students to communications theory with amplitude modulation and demodulation. The analog modulation part covers the generation and detection of doubleside band suppressed carrier dsbsc modulation, doubleside band with carrier also known as am modulation, quadrature amplitude modulation qam, and frequency modulation. These are covered in chapter 5 of 2, or chapter 3 of 1. When we take a demodulation unit of am receiver, it consists of rc filter and a diode which will demodulate the message signal or modulating signal from modulated am signal, which is unlike in frequency modulation. Time division multiplexing of 2band limited signals.
Cme312 lab manual frequency modulation experiment 8. To study frequency modulation and determine its modulation factor 4. Through this dissertation, this paper pointed out the operation of fm modulation and demodulation theoretically. Its amplitude a, which leads us to the class of systems designated as amplitude. Analog communications lab manual pdf ac lab manual pdf.
Matlab, time and frequencydomain representation of signals, and processing of speech signals. Cme312 lab manual dsbsc modulation and demodulation experiment 6 experiment 2 spectral analysis. Frequency modulation fm is the standard technique for highfidelity communications as is evident in the received signals of the fm band 88108 mhz vs. Frequency modulation is a process of changing the frequency of a carrier wave in accordance with the slowly varying base band signal. Demonstrate understanding of various amplitude modulation and demodulation techniques. This paper provides a comprehensive survey on various modulation and demodulation techniques such as amplitude shift keying ask, frequency shift keying fsk and phase shift keying psk of the. This lab exercise is a nice illustration of the utility of the software defined radio approach, since the algorithms for creating and demodulating fm in software are much simpler than those used in the traditional hardware approach. The radio wave was called a carrier, since it was seen to carry the speech information with it. To study and perform pulse amplitude modulation and demodulation.
The amplitude of the carrier remains constant phase modulation pm another form of analog modulation technique which we will not discuss. Scientech techbook 2203 frequency modulation and demodulation techniques is a comprehensive learning solution specifically designed to study basic operation as well as to provide conceptual and step by step understanding of frequency modulation and demodulation techniques through observation of waveforms at various test points. Build simple fm demodulator by using frequency discriminator 2. Also before coming to the lab, you should complete the lab preparation and hand it to the t. Shashi heres a video i recorded of our lab expert performing frequency modulation and frequency demodulation experiment. Each channel sharing scheme a set of basis vectors.
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