Low-frequency am modulation simulation with labview tutorial pdf

Labview programs are called virtual instruments or vis, because their. Amplitude modulation am source the am source singlefrequency amplitude modulation source generates an amplitudemodulated wave. This is the range of carrier frequencies available. The fundamentals of signal generation electronic design. A modulator, followed by a filter, is sufficient to obtain an amplitude modulated signal, but it should be pointed out that this type of modulation generates numerous distortions. Since the signal strength of this lowfrequency signal is less, it has to be given to an audiofrequency amplifier to strengthen the signal to a desired level. In low frequency applications up to 100khz, passive filters are generally constructed using simple rc resistorcapacitor networks, while higher frequency filters above 100khz are usually.

As part of the modulation practices we simulated this am modulator circuit to test the effects of the modulation quotient in the signal we plan to transfer. Amplitude and frequency radio frequency modulation. This brief demo shows how to use graphical programming in national instruments labview to quickly build a simple simulation showing lowfrequency am modulation. In single polarity pulse amplitude modulation, there is fixed level of dc bias added to the message signal or modulating signal, so the output of modulating signal is always positive. For a laboratory student, the kind of labview program is a freefall, a pendulum, a centrifugal force, a collision, a currentmagnetism and a optics experiment. For low frequency applications, silicon is used, and for high frequency applications gallium arsenide is used. Frequency modulation is widely used on frequencies above 30 mhz, and it is particularly well known for its use for vhf fm broadcasting. Pdf this tutorial discusses analogmodulation techniques with the. The frequency band used for am radio is about 550 to 1720 khz.

Modified frequency modulation mfm is a runlength limited rll coding scheme used to encode the actual databits on most floppy disks. In other words they filterout unwanted signals and an ideal filter will separate and pass sinusoidal input signals based upon their frequency. Pdf a labviewbased analog modulation tool for virtual and. Pulse compression is a generic term that is used to describe a waveshaping process that is produced as a propagating waveform is modified by the electrical network properties of the transmission line. The given matlab program is capable of accepting two input frequencies and modulation index from the user. This generator can generate 1 hz to 25 mhz sine and square waves, 1 hz to 5 mhz triangle and ramp waveforms, and 1 mhz to 10 mhz pulses. Pdf simulation of analog modulation and demodulation. We use windows program and labview program that communicates with interface and collects data. While changing the amplitude of a radio signal is the most obvious method to modulate it, it is by no means the only way. Pdf a labviewbased analog modulation tool for virtual. Modulation also provides a means for simultaneous transmission of several signals, using the same transmission channel hertzian, cable.

It was first introduced in hard disk drives in 1970 with the ibm 3330 and then in floppy disk drives beginning with the ibm 53fd in 1976. A labview based analog modulation tool for virtual and. The whistler virtual musical instrument vmi in labview. Am radio is the most common example of this type of modulation. Transistor bf495 t2, together with a 10k resistor r1, coil l, 22pf variable capacitor vc, and internal capacitances of transistor bf494 t1, comprises the colpitts oscillator the resonance frequency of this oscillator is set by trimmer vc to the frequency of the transmitting station that we wish to listen. In the double polarity pulse amplitude modulation, the output of modulating signal will have both positive and. The radio wave was called a carrier, since it was seen to carry the speech information with it. Understanding rf circuits with multisim 10 a workbook with 21 circuit experiments by tracy shields notice to the reader the reader is expressly warned to consider and adopt all safety precautions that might be indicated by activities described herein and to avoid all potential hazards.

Introduction to signal processing through music connexions by author support on. 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. The pulse is internally modulated in phase or in frequency, which provides a method to further resolve targets which may have overlapping returns so. An advantage of frequency modulation is that it has a larger signaltonoise ratio and therefore rejects radio frequency interference better than an equal power amplitude modulation am signal. Amplitude modulation am is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. Lowfrequency am modulation simulation with labview duration. Rf basics, rf for nonrf engineers dag grini program manager, low power wireless. Low cost function generator amplifier diy dmc, inc. Use of amplitude modulation cues recovered from frequency. Fpga implementation of an amplitudemodulated continuouswave. I want to do amplitude modulation of an audio signal. What is the easiest way to determine the peak frequency during this period. Reece identification of electrochemical processes by frequency response analysis. Musical signal processing with labview modulation synthesis.

That design wasnt meant for passing frequencies high enough to be able to pass an audio file, e. Niknejad university of california, berkeley eecs 142 lecture 15 p. Very little frequency modulation will be produced if this phase shift is the result of noise modulated by a lowfrequency audio component, but the frequency modulation will increase directly with the. This points to a shortcoming of amplitude modulation, that only a. A labview based analog modulation tool for virtual and real. Come browse our large digital warehouse of free sample essays. So during that 2 seconds the frequency is in flux, changing until it resettles at 60hz. I got the idea for this circuit from one of my professors. Note that the best peaktopeak amplitude of the lowfrequency modulation is equal to the spectral line width. Amplitude modulation a1 49 you will see in this experiment, and in others to follow, that there is no problem in generating an am signal with a depth of modulation exceeding 100%, and without. I might give labview a shot my uni gives us free access in case it cant be done on matlab. The instrument comes with a serial port and an optional ieee488 gpib port. Mar 22, 2007 this brief demo shows how to use graphical programming in national instruments labview to quickly build a simple simulation showing low frequency am modulation.

Digital modulation in somewhat similar to the analog modulation except base band signal is. In order for the lowpass to detect the information envelope, the frequency of the. Mar, 2018 the ptype and ntype layers of the varactor diode are made up of silicon or gallium arsenide depending on the type of application for which it is used. Here, we examined the scalefree properties of the restingstate functional magnetic. The phase locked loop pll as a demodulator will be studied in the next section. Pulseamplitude modulation is widely used in baseband transmission of digital data, with nonbaseband applications having been largely superseded by pulsecode modulation, and, more recently, by pulseposition modulation. Amplitude modulation am is the simplest and the oldest of modulation methods, primarily because the stage of demodulation, at the receiver, is simple to carry out. The process of superimposing a low frequency signal onto a high frequency signal three modulation schemes available. Design and simulation of amplitude modulation network for. Modulation frequency an overview sciencedirect topics. Electronics workbench multisim 8 simulation and capture. These parameters can be modified in accordance with a low frequency information signal to obtain the modulated signal. It can be used to build and analyze communications circuits. Fm modulacao por frequencia ofdm sim4 matlab code for fading channel.

Frequency modulation so far, the assumption has been that the spectrum analyzer has a resolution bandwidth narrow enough to resolve the spectral components of the modulated signal. Simulation time is chosen to be 2 secs for the spectrum analyzers. This application proposes a data hiding scheme for amplitude modulation am radio broadcasting systems. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that of the message signal being transmitted. Lowfrequency modulation tremolo effect miniproject vibraphone virtual musical instrument vmi in labview. The modulation of a signal is essential if one wishes to transmit it over long distances. Get the knowledge you need in order to pass your classes and more. Analog modulation refers to the process of transferring digital low frequency baseband signal, like digital bitstream from computers over a higher frequency carrier signal such as a radio frequency band. National instruments hardware or in a simulation environment to generate. Labview real time module user manual, available at. Preparation of a virtual toolkit for communication systems.

An am wave may thus be dscribed, in the most general form, as a function of time. For example, a common modulation test tone is 400 hz. In particular, all telephone modems faster than 300 bits use quadrature amplitude modulation qam. The foundation is a michigan,usabased 501 c 3 nonprofit corporation existing to provide education in and collaboration around the design and use of opensource software and hardware in embedded computing. The information transmitted is music and talk which falls in the audio spectrum. This technique contrasts with frequency modulation, in which the frequency. This tutorial discusses analog modulation techniques with the labview based analogmod package, developed for the illustration of different modulation. Frequencyshift keying fsk is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. Set channel a to output an am signal with fc30khz, vc1v fm1khz, and m0.

This tutorial discusses analogmodulation techniques with the labviewbased analogmod package, developed for the illustration of different modulation types in undergraduate labs. This zerocrossingcounter demodulator will be modeled in the latter part of the experiment and used for demodulation low frequency fm. A labviewbased analog modulation tool for virtual and real experimentation article pdf available in ieee antennas and propagation magazine 546. What is fm, frequency modulation electronics notes. The message signal is, for example, a function of the sound to be reproduced by a. If any of the lo leaks into the rf path, then it will selfmix and produce a dc offset. Implementation of fhma communication system using labview. Modulation, analog modulation, digital modulation, am,fm. The two audio clips used in the example are available here. Envelope detection has numerous applications in the fields of signal processing and communications, one of which is amplitude modulation am detection. Am, fm, and fsk modulation are available am modulation can also be done on the arbitrary waveforms.

Am, fm, and pm modulation formats, and is capable of if to iq. Its other inputs are the amplitude of the carrier, the sampling frequency of the baseband signal. Observe the results on the scope and spectrum analyzer for 25, 50, 75, and 100 percent modulation sketch roughly in lab notebook. So this form of amplitude modulation offers a way to create complex nonharmonic timbres that change pitch normally as you play up and down the keyboard. Pdf an analog method to modulate and demodulate signals is. Aug 28, 2015 double polarity pulse amplitude modulation. Feb 27, 20 simulate lowfrequency am modulation with labview learn more about national instruments tools for rf and communications applications in academia view additional multimedia resources, examples, and more, to learn more about national instruments software and hardware for rf and communications applications in academia. As a result, the effective time constant of the system is. It is also possible to change the frequency of a signal to give frequency modulation or fm. Am modulation we can see that an upconversion mixer is a. Labview have large libraries with a large amount of functions for data accomplishment, signal creation, statistics, mathematics, signal conditioning, and study. Feature am fm pm function amplitude of carrier wave varies as per amplitude or voltage of. Modulation techniques pwm and pulse code modulation. If you have prior experience with matlab, you can easily develop.

Direct current dc comes from a source of constant voltage and is suited to shortrange or device level transmission. The amplitude modulated ultrasonic signal and the ir signals were sent and received at targeted distance by the matching receivers. Each tutorial in this series teaches you a specific topic of common measurement applications by explaining the theory and giving practical examples. Learn more about modulation, amplitude, signal processing, audio. Frequency modulation is used in a radio broadcast in the 88108mhz vhf band. A type of modulation where the phase of the carrier signal is varied accordance to the low frequency of the message signal is known as phase modulation. Heres a simple fm receiver with minimum components for local fm reception. Amplitude modulation am interactive simulations edumedia. As an example, the following figure shows the amplitude modulation with. Modulation synthesis8 amplitude modulation am and frequency. Lowfrequency am modulation simulation with labview youtube. Modulationtypesamplitude,frequency,phase modulation.

In the context of radio communication, near the end of the 2oth century, few modulated signals contain a significant component at carrier frequency. Amplitude modulation is defined as the process in which the amplitude of the carrier wave ct is varied about a mean value, linearly with the baseband signal. Here is the matlab code for frequency modulationfm, the use of particular code is also given as comments %comment field. The maximal variation of the envelope of the voice tone f1 during one period of the bass tone is. This tutorial is part of the national instruments measurement fundamentals series. Design and simulation of amplitude modulation network for analog communication. An introduction to electrochemical impedance spectroscopy. Modulation is explained along with detailed description of its types like amplitude modulation,frequency modulation ad phase modulation. In modern wireless communications systems, signal generators supporting a range of digital modulation formats are commonly.

Doublesideband suppressed carrier modulation dsbsc in full am dsbam, the carrier wave ct is completely independent of the message signal mt, which means that the transmission of carrier wave represents a waste of power. But we may want to view lowfrequency modulation with an analyzer that does not have sufficient resolution. Electrical circuits and systems ii lab amplitude modulated radio frequency transmission system introduction an amplitude modulated radio frequency transmission system consists of a modulator in which a sinusoidal high frequency carrier waveform, fc. With this in mind, a focused search for abnormities in scalefree dynamics is of considerable clinical relevance to migraine and other clinical pain disorders. Frequency modulation fundamentals, august 1939 qst rfcafe.

Build the simulink model of am modulator and demodulator figure7 explained in this manual. Matlab code for frequency modulation fm with modulation. Rf mixing multiplication basics rf mixers and the process of rf mixing or multiplication is key to many rf circuit enabling signal to be converted from one frequency to another as well as providing phase comparison. Amplitude, phase and frequency are the three key parameters of a sine wave. Introduction to communication systems using national. The resulting lowfrequency output of the lockin is again demodulated by another phasesensitive lockin.

Doublesideband suppressed carrier modulation dsbsc in full am dsb am, the carrier wave ct is completely independent of the message signal mt, which means that the transmission of carrier wave represents a waste of power. Lets take that case where the modulation index is low say in the region of 0. A majority of function generators are only capable of driving a couple of hundred milliamps, which is fine for most applications. This points to a shortcoming of amplitude modulation, that only a fraction of the total. It is old style waveform data just an array of single precision. Basic radio awareness modulation and radio building blocks how does modulation work. Amplitude modulation am, frequency modulation fm and phase modulation are the most common analog modulation techniques. Varactor diode construction, working, characteristics. This tutorial covers an introduction to rf, wireless, and highfrequency signals and systems. Am modulation where the amplitude of the carrier does not depend on the value of the modulating signal. The effects of additive noise in the frequency domain doublesideband amplitude modulation, uniform. The present study was designed to extend this finding for a wide range of listening conditions, where the original speech. Spectral analysis studies the frequency spectrum contained in discrete, uniformly sampled data.

This tutorial discusses analog modulation techniques with the labview based analogmod package, developed for the illustration of different modulation types in undergraduate labs. A labview based analog modulation tool for virtual and real experimentation article pdf available in ieee antennas and propagation magazine 546. Digital amplitude modulation involves varying the amplitude of a carrier wave in discrete sections. Amplitude modulation is a powerful tool that allows you to create and play new sounds that you cannot obtain using conventional oscillators alone. Am modulation of audio file matlab answers matlab central. The signals envelope is equivalent to its outline, and an envelope detector connects all the peaks in this signal. The programming language used in labview, called g, is a dataflow.

In this video you will see amplitude modulation using different type of signals and channels. The process and the signal were called amplitude modulation, or am for short. Simulate signal express vi in the waveform generation palette. The only significant side bands will be those closest to the carrier frequency, and the result will look similar to that we obtained last month using amplitude modulation see figure 9, above. Multisim 8 component reference guide 15 source components 1.