Modulation by sanjay

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Modulation by sanjay

  1. 1. MODULATION BY- SANJAY KUMAR 0900321088 EN-2(A)
  2. 2. INTrODUcTION Modulation is the process by which some characteristics of a carrier is varied in accordance with a modulation wave . Modulation is the process of putting information onto a high frequency carrier for transmission (frequency translation). such a modification is achieved by mean of a process called modulation .
  3. 3.  In the modulation process, the baseband signle is called “modulating signal” and anther higher frequency signal is called as the “carrier”. The carrier signal will carry the modulating signal to the destination.
  4. 4. DIffereNT Of MODULATION MeThOD Analog modulation - The modulating signal and carrier both are analogue signal. TYPES : Amplitude modulation (AM), Frequency modulation (FM), Phase modulation (PM)
  5. 5. fIgUre Types Of ANALOg- MODULATION
  6. 6.  Digital modulation - The modulating signal is a digital signal , but the carrier is an analogue signal. TYPES : Amplitude Shift Keying (ASK), Frequency Shift keying (FSK), Phase Shift Keying (PSK)
  7. 7. AMpLITUDe MODULATIONAmplitude Modulation is a process of changing the amplitude of a high frequency carrier signal in proportion with the instantaneous value of modulating signal (information). Amplitude Modulation is the simplest and earliest form of transmitters.
  8. 8. fIgUre : AMpLITUDe MODULATION
  9. 9. AM – BAsIc DefINITIONs 5The AM signal: s ( t ) = Ac [1 + k • m( t ) ] cos ωc t 0 -5 0 0 .0 1 0 .0 2 0 .0 3 0 .0 4 0 .0 5 0 .0 6 0 .0 7 0 .0 8 0 .0 9 0 .1The modulating signal: 1m( t ) = Am cos ωct 0 -1The Carrier Signal: 0 0 .0 1 0 .0 2 0 .0 3 0 .0 4 0 .0 5 0 .0 6 0 .0 7 0 .0 8 0 .0 9 0 .1 1c( t ) = Ac cos ωc t 0 -1 0 0 .0 1 0 .0 2 0 .0 3 0 .0 4 0 .0 5 0 .0 6 0 .0 7 0 .0 8 0 .0 9 0 .1
  10. 10. AM chArAcTerIsTIcs AM is a nonlinear process Sum and difference frequencies are created that carry the information
  11. 11. MODULATION INDex The ratio between the amplitudes between theamplitudes of the modulating signal and carrier,expressed by the equation: Em m= Ec
  12. 12. MeAsUreMeNT Of MODULATION INDex
  13. 13. OverMODULATION When the modulation index is greater than 1, overmodulation is present
  14. 14. MODULATION INDex fOr MULTIpLe MODULATINg freqUeNcIesTwo or more sine waves of different, uncorrelated frequencies modulating a single carrier is calculated by the equation: 2 2 m= + • m m +• • 1 2
  15. 15. fULL-cArrIer AM: freqUeNcy DOMAIN Time domain information can be obtained using an oscilloscope f usb = f c + f m f lsb = f c − f m Frequency domain information can be calculated using mE c Fourier methods, but E lsb =E usb = trigonometric methods are 2 simpler and valid Sidebands are calculated using the formulas at the right
  16. 16. BANDwIDTh• Signal bandwidth is an important characteristic of any modulation scheme• In general, a narrow bandwidth is desirable• Bandwidth is calculated by: B = 2 Fm fc-fm fC fc+fm 2fm
  17. 17. AppLIcATIONs AMpLITUDe MODULATION AM applications include broadcasting in medium- and high-frequency applications,  CB radio , and  aircraft communications
  18. 18. ThANK yOU

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