Students have to bring the lab manual cum observation book, record etc along with them whenever they come for lab work. The second is to investigate classical analog amplitude modulation and the envelope detector. To study and perform pulse width modulation and demodulation. There are two common forms of angle modulation, namely, phase modulation and frequency modulation. Ece 4670 spring 2014 lab 5 frequency modulation, demodulation. This file generates the frequency modulated signal for a given carrier signal frequency, message signal frequency and modulation index. Examples of this are in the lab 3 jupyter notebook sample. The value of freqdev must satisfy freqdev files for seamless import into jupyter.
Carrier sinewave frequency 10 mhz, amplitude 1 vpp with frequency deviation constant 10. The simulation of modulation schemes such as amplitude modulation and frequency modulation are designed using vi models are used as reference for. Modulation is defined as the process in which some characteristics of the signal called carrier is varied according to the modulating or baseband signal. If poss explain me the working of each syntax in the program. Signal multiplication of baseband signals and radio frequency rf signals is quite challenging. Am modulation, quadrature amplitude modulation qam, and frequency. The focus of this lab is to familiarize the student with the modulation and demodulation of an am signal. An important feature of angle modulation is that it can provide better. The objective of this lab is to introduce more complicated signals that are related to the basic sinusoid. To measure the percentage of modulation, and total power in frequency modulation. It is also possible to change the frequency of a signal to give frequency modulation or fm. The value of freqdev must satisfy freqdev frequency modulation.
The specification for amplitude and frequency are given in the m file. Considerable upfront effort will be placed on the exploration of circuits that perform signal multiplication. Pulsecode modulation pcm is a method used to digitally represent sampled analog signals. Understand signal analysis in the time, frequency, and. The block diagram of a phase locked loop pll is shown in figure 1. In the first experiment, we analyzed the effect of varying the amplitude of a sinusoidal carrier. Pcm modulation is commonly used in audio and telephone transmission.
Angle modulation changes the phase of a signal as well as its amplitude, where amplitude modulation leaves the phase unchanged. Suppose there is a nonmodulated carrier at the input. The files include frequency modulation and demodulation technique. Pdf simulation of analog modulation and demodulation. In this experiment, a carrier signal and an audio modulating signal are applied to the modulator ic mc 1496 and the produced modulated waveform is observed. Build simple fm demodulator by using frequency discriminator 2. For example amplitude modulation, phase modulation, frequency modulation. The operation theory of pcm modulation pcm modulation is a kind of source coding. During this lab you will create an fm signal by modulating an audio waveform onto a carrier, examine the spectrum of the modulated carrier, evaluate the modulated carrier when the modulation index is varied and.
The phase of the carrier wave is also kept constant. The use of fm for audio synthesis was discovered and developed by john m. I ntroduction an amplitude modulated signal is composed of both low frequency and high frequency components. However if st is sinusoidal, then the instantaneous frequency deviation of the anglemodulated signal is. Designing and analyzing frequency modulator and demodulator objective. Set channel a to output an am signal with fc30khz, vc1v fm1khz, and m0.
In the context of radio communication, near the end of the 2oth century, few modulated signals contain a significant component at carrier frequency. These signals which implement frequency modulation fm and amplitude modulation am are widely used in communication systems such as radio and television. 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. Frequency modulation is widely used for fm radio broadcasting. May 19, 2006 i am trying to frequency demodulate a frequency modulated ecg signal done by a hardware circuit. The radio wave was called a carrier, since it was seen to carry the speech information with it. To study and perform frequency modulation and demodulation. Cme312 lab manual frequency modulation experiment 8. Include things like which igbts are on when and what the output voltage waveform looks like. Phase modulation is another type of angle modulation very similar to frequency modulation. Also before coming to the lab, you should complete the lab preparation and hand it to the t. Using matlab m file and simulink to implement fm modulation and demodulation.
In case of over modulation, the modulation index is greater than one and envelope distortion occurs. Frequency modulation, fm detection, demodulation, discrimination in order to use the modulation on an fm signal, it is necessary to extract the modulation, i. Sysc 3501 lab 3 report rashad alsaffar 101006781 mohammad danyal 101003904 1 introduction the purpose of this lab was to understand the concepts of frequency modulation and phase modulation. If the vco was tuned precisely to the frequency of the incoming carrier. Experiment 5 frequency modulation 1 objective to understand the principles of frequency modulation and demodulation. Frequency modulation is widely used on frequencies above 30 mhz, and it is particularly well known for its use for vhf fm broadcasting. Demonstrate understanding of frequency modulation and demodulation technique. To understand the theoretical foundations for angle modulation as well as frequency modulation fm and demodulation. Modulation is a process by which characteristics of a high frequency carrier signal are altered to convey information contained in a lower frequency message. I am trying to frequency demodulate a frequency modulated ecg signal done by a hardware circuit. University of north carolina at charlotte department of. Lab 6frequency modulation formal report required groups of two this lab will have you create and analyze some simple frequency modulated fm waveforms.
Dsb modulation, the transmitted carrier is created from. A message signal was sent through a function generator, producing outputs at different rms values. In radio transmission, an advantage of frequency modulation is that it. In a pcm stream, the amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to. Understand signal analysis in the time, frequency, and modulation domains this tutorial explains the fundamentals of time, frequency, and modulationdomain analysis from the perspective of. The factor 2 in the equation is to account for both the upper and lower sidebands left and. Build simple envelope detector for fm demodulation. Modulation is the process in which some property of the high frequency wave, also called as carrier wave is altered in such way by low frequency information signal, called as modulating signal, to transmit form one place to other place through air. While changing the amplitude of a radio signal is the most obvious method to modulate it, it is by no means the only way. Frequency and phase modulation sharlene katz james flynn overview history why fm. Amplitude modulation this experiment examines the characteristics of the amplitude modulation am process. The demodulation is performed by an envelope detector.
Feel free to use the lab to practice your skills before the. Pcs lab manual page 1 laboratory manual principles of communication system lab ee226f ivth semester prepared by. Analog communications lab manual pdf ac lab manual pdf. To construct a frequency modulated waveform using fm transmitter and demodulate it using fm receiver. Oct 19, 2018 theory related also explained in detail. Chowning has said, while performing some not very rigorous experiments with vibrato in 196768, i suddenly realized that with extreme vibrato, i. Lab 3 mixer s and amplitude modulation the underlying theme of this lab is amplitude modulation. Fm modulation introduction in this lab, you will investigate frequency modulation fm and its properties. In a pcm stream, the amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital.
Frequency modulation is a form of modulation, which represents information as variations in the instantaneous frequency of a carrier wave. The underlying theme of this lab is angle modulation, in particular frequency. Frequency modulation and demodulation file exchange. Complex waveforms iii frequency modulation another common method of obtaining complex waveforms is by frequency modulation fm. Analog communications lab manual pdf ac lab manual pdf file please download the analog communicati. The term and technology us used in both telecommunications and signal processing in analog frequency modulation, such as fm radio broadcasting of an audio signal representing voice or music, the instantaneous frequency. The underlying theme of this lab is angle modulation, in particular frequency modulation fm. What is fm, frequency modulation electronics notes. The carrier frequency f c is much greater than the highest frequency component.
Frequency modulation fm is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. Learning to write a vi that uses the usrp as an transmitter and a receiver. Frequency modulation fm file exchange matlab central. Frequency modulation software free download frequency. Frequency and phase modulation california state university. Should take only the lab manual, calculator if needed and a pen or pencil to the work area. It is still in use today in a variety of systems, including, of course, am broadcast radio. Frequency modulation software free download frequency modulation top 4 download offers free software downloads for windows, mac, ios and android computers and mobile devices. Lab manual frequency modulation experiment 8 experiment 2 phase look loop. In an fm signal, the frequency of the signal is changed by the modulation baseband signal while its amplitude remains the same. The carrier amplitude is constant and the phase variation of the signal contains the information.
Lab 4 assignment you will need to write the following code template files are provided worlds. Briefly describe its operation in 1800 modulation mode. Phase modulation, and frequency modulation are both the modulation. Page 7 and frequency amplitudes of the two sidebands can be reduced to zero by reducing the amplitude of the modulating audio. The spectrum of an fm signal is quite complicated and is dependent on mf. To implement the simulink models for fm including a basic sinusoid and a multimedia file music to analyze each signal in time and frequency domains. It is also used in telemetry, radar, seismic prospecting, and monitoring newborns for seizures via eeg, twoway radio systems, music synthesis, magnetic taperecording systems and some videotransmission systems. Overmodulated am signals and its requirement for coherent detection are also considered. Observe the results on the scope and spectrum analyzer for 25, 50, 75, and 100 percent modulation sketch roughly in lab notebook. Phase and frequency modulations are techniques that modify the instantaneous phase and frequency, respectively, of a sinusoid in a way dictated by an information signal f. The process and the signal were called amplitude modulation, or am for short. The m file will show these values in the matlab command window. Modulation is the process in which some property of the high frequency wave, also called as carrier wave c, is altered in such way by low frequency information signal, called as.
Transmitting and receiving a multimedia file using fm via usrp. To study and perform pulse amplitude modulation and demodulation. Exercise 51 generating ssb signals by the filter method 91. Some useful tutorials can be found on the ee 370 courselab website. Prelab theory a frequency modulation fm waveform can be represented mathematically by. Jan 20, 2014 this file generates the frequency modulated signal for a given carrier signal frequency, message signal frequency and modulation index. The main advantage is the pcm modulation only needs 8 khz sampling frequency to maintain the original quality of audio. In analog applications, the carrier frequency is varied in direct proportion to changes in the amplitude of an input signal. Chowning in the late 1960s and described in the synthesis of complex audio spectra by means of frequency modulation, jaes 21. Complex waveforms iii frequency modulation basicsynth. Frequency modulation is the instantaneous change of the carrier frequency, fc by the. Frequency demodulation matlab fmdemod mathworks india. In frequency modulation, the amplitude of the carrier wave is kept constant but its frequency is varied in accordance with the amplitude of the audio frequency signal. Overmodulated am signals and its requirement for coherent detection are.
358 712 309 562 675 970 1011 452 1136 1002 58 561 1236 641 706 383 335 751 1365 151 571 1522 1277 1402 381 1319 585 1345 1138 242 324 881 1195 114 553 1395 839 292