The purpose of this lab is for you to gain familiarity with the concepts of amplitude modulation and demodulation. Introduction in chapters 1 and 2 you studied how to apply intelligence modulation to an rfcarrier wave. 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. To perform the amplitude modulation and demodulation using am kit. By the end of this experiment, the student should be able to.
The second is to investigate classical analog amplitude modulation and the envelope detector. To generate amplitude modulated wave and determine the percentage modulation. Pulse amplitude modulation pam is the simplest pulse modulation scheme. The simplest form of the pam modulator is an analog switch that is turned on and off at the rf carrier pulse rate. Frequency division multiplexing, fdma amplitude modulation and demodulation. This, for a sinewave, is equivalent to a phase reversal shift. To demodulate the modulated wave using envelope detector. No information is lost, but the energy is redistributed in the frequency domain. A demodulator is an electronic circuit that is mainly used to recover the information content from the modulated carrier wave. Analog signal is characterized by the fact that its amplitude can take on any value over a continuous. Prof mist mist, hyderabad ece department page 7 experiment 1 4. In this modulation, the signal is sampled at regular intervals and each sample is made proportional to the amplitude of the modulating signal. You must determine the analog filters passband edge frequency. T12 measure the peaktopeak amplitude of the am signal, with m 1, and confirm that this magnitude is as predicted, knowing the signal levels into the multiplier, and its k factor.
It is still in use today in a variety of systems, including, of course, am broadcast radio. The standard form the amplitude modulated wave is defined as where carrier, modulating signal modulation index is defined as amplitude modulated signal. Ee3 lab 1 amplitude modulation and demodulation broadcast analog television tv signals have a bandwidth of approximately 6mhz and this is achieved with a quadrature modulation. The digital modulation experiments include pcm encoding and decoding, line codes and digital. Demodulation output pcm operation with ac input modulation. To study frequency modulation and determine its modulation factor 4. Cme 312lab communication systems laboratory cme312 lab. Modulation allows us to transmit multiple signals in the same medium i. Lab manual amplitude modulation and demodulation experiment 5 experiment 2 figure 5. Each channel sharing scheme a set of basis vectors.
There are different types of modulation and so are demodulators. The original waveform amplitude is quantized with a resulting loss of information. The ideal envelope detector is a circuit which consists of two parts, the first part is a rectifier to take the absolute value of the signal, while the second part is lpf to remove unwanted component. In your lab write up compare this with what is expected for a modulation depth of m 1. Analog communications lab manual pdf ac lab manual pdf. As before, this may require a manual adjustment of the voltsdiv and secdiv to obtain a suitable waveform. The fmmodulated signal has its instantaneous frequency that varies linearly with the amplitude of the message signal. Describe phase demodulation circuit operation for the peak, lowpass filter, and conversion detectors. Frequency of the input carrier is fixed at constant amplitude of 1. The idea is simple, though the notion that it can be used to modulate signals for transmission was hardly obvious before its discovery.
C67 dsk implementation using cc for this part of the lab, you will demodulate the am signal generated by the arbitrary waveform generator on your lab bench. Amplitude modulation is one of the earliest radio modulation techniques. Build the simulink model of am modulator and demodulator figure7 explained in this manual. In pulse amplitude modulation system the amplitude of a carrier pulse train is varied in accordance with the instantaneous level of the modulating signal. Connections are made for the am modulator and demodulator as shown in the circuit diagrams. Restoring or recovering the message signal from the received modulated waveform that is generally corrupted by noise types of am detectors. Adjust the carrier and modulated signals for a modulation index of 0.
Dutton ee3 winter 2004 1 ee3 lab 1 amplitude modulation and demodulation 1 lab notes a word about power. Cme312 lab manual dsbsc modulation and demodulation experiment 6 experiment 2 dsb objectives. An amplitude modulated signal is composed of both low frequency and high frequency. Demodulation is defined as extracting the original informationcarrying signal from a modulated carrier wave. 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.
Experiment 2 experiment 6 experiment dsb sc modulation and. Demonstrate the modulation and demodulation process of dsbsc. To study amplitude demodulation by linear diode detector 3. Pulse amplitude modulation pam theory of and its applications. University of north carolina at charlotte department of. 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. In singlechannel efield sensing, the carrier we transmit is m, the sensed value is a, and the noise is n vectors. The pulse may take any real voltage value that is proportional to the value of the original waveform. Vestigial sideband amplitude modulation vsbam is a modulation that improves the spectral e.
Pulse amplitude modulation is the basic form of pulse modulation. As before, this may require a manual adjustment of the voltsdiv and secdiv. Amplitude modulation and demodulation electrical and computer. The receivers used to listen to amdsbc are perhaps the simplest receivers of any radio modulation technique. Ece 4670 communication systems laboratory experiments manual. Carrier modulation allows the transmission of modulating frequencies without the use of transmission wire as a medium.
Now we will observe the demodulation of an am signal with the circuit shown in figure 87. Analog communication lab manual, prepared by nakka. Before we study in detail about pam lets know the concepts of modulation. In amplitude modulation the amplitude of the carrier wave ct is varied linearly with the instantaneous amplitude of the message signal mt.