Introduction To Modulation: Amplitude Modulation(AM)
Introduction to Modulation:Amplitude Modulation(AM)Sharlene KatzJames Flynn
OverviewModulation Overview Basics of Amplitude Modulation (AM) AM Demonstration GRC Exercise 2Flynn/Katz 7/8/10
Why do we need Modulation/Demodulation?Example: Radio transmission VoiceMicrophoneTransmitterElectric signal,20 Hz – 20KHzAntenna:Size requirement 1/10 wavelengthc 3 10 85λ 10 100km3At 3 KHz:f 3 10 .1λ 10km3Antenna too large!Use modulation totransferinformation to ahigher frequencyFlynn/Katz 7/8/10
Why do we need Modulation/Demodulation?(cont’d)Frequency AssignmentReduction of noise/interferenceMultiplexingBandwidth limitations of equipmentFrequency characteristics of antennasAtmospheric/cable properties 4Flynn/Katz 7/8/10
Basic Concept of ModulationThe information source Typically a low frequency signalReferred to as the “baseband signal”x(t)X(f)tfCarrier A higher frequency sinusoidExample: nalModulated Signal 5Some parameter of the carrier (amplitude, frequency, phase) is varied inaccordance with the baseband signalFlynn/Katz 7/8/10
Types of ModulationAnalog Modulation Amplitude Modulation, AMFrequency Modulation, FMDouble and Single Sideband, DSB and SSBDigital Modulation 6Phase Shift Keying: BPSK, QPSK, MSKFrequency Shift Keying, FSKQuadrature Amplitude Modulation, QAMFlynn/Katz7/8/10
Amplitude Modulation (AM)Block Diagram x(t)mTime Domain xxAM(t) Ac [1 mx(t)]cos wct Ac cos wctFrequency Domain XAM(f)X(f)-fm7fmSignal information iscontained in thesidebandsff-fcfcFlynn/Katz 7/8/10
Traditional AM DemodulatorsSynchronous Detector xAM(t) Ac [1 mx(t)]cos wctXAM(f)-fcfcfEnvelope Detector 8Low PassFilterxcos wct-2fc2fcfFlynn/Katz 7/8/10
Receiving AM with SDRUSRP and Computer with GNU Radio Software USRPBasic Rx64Ms/sA/Dor256Ks/sFPGAShifts by -710KHzComputer(GNU Radio)Stored USRP File9Flynn/Katz 7/8/10
AM Modulation Demonstration Receiving off-air signalsUsing a captured file sourceGRC Exercise10Flynn/Katz 7/8/10
Questions?11Flynn/Katz 7/8/10
Types of Modulation 6 Flynn/Katz 7/8/10 Analog Modulation Amplitude Modulation, AM Frequency Modulation, FM Double and Single Sideband, DSB and SSB Digital Modulation Phase Shift Keying: BPSK, QPSK, MSK Frequency Shift Keying, FSK Quad
9/18/2016 9Nurul/DEE 3413/Modulation Types of Modulation Pulse Modulation Carrier is a train of pulses Example: Pulse Amplitude Modulation (PAM), Pulse width modulation (PWM) , Pulse Position Modulation (PPM) Digital Modulation Modulating signal is analog Example: Pulse Code Modulation (PCM), Delta Modulation (DM), Adaptive Delta Modulation (ADM), Differential Pulse
3. Amplitude Modulation . a. General. The amplitude, phase, or frequency of a carrier can be varied in accordance with the intelligence to be transmitted. The process of varying one of these characteristics is called modulation. The three types of modulation, then are amplitude modulation, phase modulation
10.3 Analog Modulation Schemes 10.4 Amplitude Modulation 10.5 Frequency Modulation 10.6 Phase Shift Modulation 10.7 Amplitude Modulation And Shannon's Theorem 10.8 Modulation, Digital Input, And Shift Keying 10.9 Modem Hardware For Modulation And Demodulation 10.10 Optical And Radio Frequency Modems 10.11 .
P. Ribière « Modulation et démodulation d'amplitude ». Collège Stanislas. Année Scolaire 2016/2017. J-P. Muller « Modulation d'amplitude » Physique appliquée. Sept. 2009. P.Poulichet « Modulation analogique en amplitude et en fréquence ». Ecole de la chambre de commerce et de l'industrie de Paris. Mars 2010.
Modulation allows for the designated frequency bands (with the carrier frequency at the center of the band) to be utilized for communication and allows for signal multiplexing. Amplitude modulation (AM) is an analog and linear modulation process as opposed to frequency modulation (FM) and phase modulation (PM).
Department of Electronics & Communication Engineering Page 3 1.Amplitude Modulation & Demodulation Aim To study the function of Amplitude Modulation & Demodulation (Under modulation, Perfect modulation & Over modulation) using Matlab Simulink. Apparatus Required
Ans: Modulation is defined as the process in which some characteristics of the signal called carrier is varied according to the modulating or baseband signal. For example – Amplitude Modulation, Phase Modulation, Frequency Modulation. In case of over modulation, the modulation index is
ADVANCED ENGINEERING MATHEMATICS By ERWIN KREYSZIG 9TH EDITION This is Downloaded From www.mechanical.tk Visit www.mechanical.tk For More Solution Manuals Hand Books And Much Much More. INSTRUCTOR’S MANUAL FOR ADVANCED ENGINEERING MATHEMATICS imfm.qxd 9/15/05 12:06 PM Page i. imfm.qxd 9/15/05 12:06 PM Page ii. INSTRUCTOR’S MANUAL FOR ADVANCED ENGINEERING MATHEMATICS NINTH EDITION ERWIN .
