The title of the experiment should be written in the page in capital letters. Amplitude modulation and demodulation objective amplitude modulation am is one of the simplest methods for modulating a sinusoidal carrier wave. This experiment deals with the basic performance of frequency modulation. Pulse amplitude modulation is the basic form of pulse modulation.
Generation of pam signal using the integrated circuit. In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. What we do in am, very roughly,is to throw away the frequency content of the message signal to. Application note of pampulse amplitude modulation signal. The transmitter circuit produces the am signal which is. The original waveform amplitude is quantized with a resulting loss of information. Tdm pulse amplitude modulation demodulation trainer st2102 learning material ver 1. Pulse amplitude modulation pulse code modulation sampling. The pulse may take any real voltage value that is proportional to the value of the original waveform. On the basis of this, an efficiency pulse stateinterval coded modulation is present for the first time and its characteristics are analyzed. Upslope of a bandpass filter circuit a lower frequency will yield a lower voltage, a higher. Pulse modulation techniques pam, pwm, ppm, pcm pulse amplitude, pulse width, pulse position, code. The transmitter side consists of a dtsmodulation circuit. The pulse amplitude modulated signal, will follow the amplitude of the original signal, as.
Figure 1 pulse sequence of the dqfcosy nmr experiment. Cahn, combined digital phase and amplitude modulation communication systems, ire transactions on communications systems, vol. Difference between pam, pwm, and ppm comparison of pwm. Tdm pulse amplitude modulationdemodulation trainer st2102. Amplitude modulation am, demodulation and their circuit. Basic concept of modulation the information source typically a low frequency signal referred to as the baseband signal carrier a higher frequency sinusoid example. To perform the amplitude modulation and demodulation using am kit. The zip archive files are password protected as described in appendix a of the text. Introduction pulse amplitude modulation pam, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Amplitude modulation is defined as a process in which the amplitude of the carrier wave ct. And the instantaneous frequency of the modulated signal is defined as.
Indian institute of technology kanpur ee 381 electrical. Pcm does not yield waveforms that vary linearly with the message however. Pulse amplitude modulated signal and demodulated signals are observed. Amplitude modulated signal can be represented by the following equation. Demodulation is defined as the process of extracting this information. Yet, am continues to be used today in many communication applications. Pdf experimental comparison of pulse amplitude modulation. In order to verify whether this modulation model is feasible and effective as well as its robustness, a wireless laser communication feasibility experiment in the hostile environments was launched. Thus for pam the carrier ct is a pulse train, whereas for dsbsc the carrier is a sine wave. A pam signal st is the product of a message signal gt and a pulse train ct. Before going to discuss the difference between pam, pwm, and ppm, let us discuss individually each. The lab volt digital communications training system, model 8085, is a complete.
Pdf pulse amplitude modulation pam and discrete multitone. Analog communication pulse modulation tutorialspoint. To study and perform pulse width modulation and demodulation. No information is lost, but the energy is redistributed in the frequency domain. Interactive coding of visual spatial frequency and. The output of the gating pulses q1 and q2 are connected to ch1 and ch2 input of the scope selector respectively.
Since pcm encodes a message into bits of 1s and 0s, it is often referred to as a source code. Data loss is also more in amplitude modulation due to noise addition. Wireless communications communications phy components modulation digital baseband modulation pam tags add tags communications digital modulation sampling signal processing spectral analysis. Connect the carrier signal at carrier ip of the modulator circuit. Sampling theorem and pulse amplitude modulation pam. In amplitude modulation am, we utilize the amplitude of the audio signal to modulate the amplitude of carrier signal, which means that the amplitude of carrier signal will be varied with the amplitude of the audio signal. The wave form of am modulation is shown in figure 3. The particular form of pulse amplitude modulation is referred to as natural pam, because the tops of the pulses follow the shape of the modulating signal.
Before we study in detail about pam lets know the concepts of modulation. The ideal modulated signal should have a minimum euclidean distance of 2. A class d amplifier uses some form of pulsewidth modulation to control the output devices. Most radio systems in the 20th century used frequency modulation fm or amplitude modulation am for radio broadcast a modulator is a device that performs modulation. Amplitude shift keying theory with lab experiment duration. Pulse amplitude modulation and demodulation trainer duration. It is an analog pulse modulation scheme in which the amplitudes of a train of carrier pulses are varied according to the sample value of the message signal. Adding of noise for amplitude modulated signal will be more when compared to frequency modulated signals. Amplitude modulation a1 53 experiment aligning the model the low frequency term at to generate a voltage defined by eqn. Lets start the seminar from analog pulse modulation 4.
By varying the amplitude of the pulses the carrier signal in proportion to the instantaneous values of. Pulse position modulation ppm is an analog modulation scheme in which, the amplitude and the width of the pulses are kept constant, while the position of each pulse, with reference to the position of a reference pulse varies according to the instantaneous sampled value of the message signal. Pulse code modulation pulse code modulation hereinafter referred to as pcm is a sampled modulation similar to pulse amplitude modulation. Amplitude modulation or am is a method to transmit signals via electromagnetic transmission. Demodulation is performed by detecting the amplitude level of the carrier. Pulse amplitude modulation pam pulse duration modulation pdm pulse position modulation ppm pulse code modulation pcm dpcm, dm,adm analog pulse modulation digital pulse modulation 3.
Two important cases of angle modulation are frequency. For flattop sampling, a sampleandhold circuit is used in conjunction with the. Baseband signals the simplest signaling scheme is pulse amplitude modulation pam with binary pam a pulse of amplitude a is used to represent a 1 and a pulse with amplitude a to represent a 0 the simplest pulse is a rectangular pulse, but in practice other type of pulses are used for our discussion we will usually assume a rectangular pulse. Its still used in radio systems to transmit audio signals although it has lesser in popularity compared to fm due to its lower signal to noise ratio. Pulse amplitude modulation pam in pulse amplitude modulation pam the amplitude of a train of constantwidth pulses is varied in proportional to the sample values of the modulating signal. Pulse amplitude modulation pam fluorometry and saturation pulse method.
However, it is the first step in another very popular conversion method called pulse code modulation. In the positive half cycle of pam signal, diode conducts and current flows through r, whereas in negative half cycle, the diode is reversed biased and. Pulse amplitude modulation pam is an analog modulating scheme in which the amplitude of the pulse carrier varies proportional to the instantaneous amplitude of the message signal. Each part may be of any convenient amplitude at the input to an adder.
To study sampling and reconstruction of pulse amplitude modulation. Modulation is defined as a process in which the amplitude of the carrier wave ct is varied linearly with. In pam the amplitude of the pulses is varied in step with the message signal. The pulse train acts as a periodic switching signal to the modulator, which when switched on allows samples of. Pdf differentialtime and pulseamplitude modulation signaling. Amplitude modulation contents slide 1 amplitude modulation slide 2 the envelope and no overmodulation slide 3 example for single tone modulation. Click here to download sign up to get notified when this product is back in stock analog communicationpulse amplitude modulation and demodulation trainer is proposed to user friendly to process the experiments and the trainer had all internal features like. Pulse amplitude modulation pam, quadrature amplitude modulation qam 12. Modulation is defined as the process by which some characteristics of a carrier signal is varied in accordance with a modulating signal.
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