1. MODUALATION Department of CE/IT

2. Outline Introduction Demodulation Amplitude Modulation – Advantages – disadvantage Frequency Modulation – Application – Disadvantage Phase Modulation Department of CE/IT

3. Introduction Whenever data is sent from one place to another via a channel, it is essential to have the data vary some characteristic of the signal that is being sent through the channel. This process is called modulation. The signal that is being modulated by the data is called the carrier. Department of CE/IT

4. Introduction The purpose of modulation is to super impose desired data information onto the carrier. The carrier acts as a vehicle for the data, which is like a passenger. They both travel over the roadway. i.e., the channel. All modulation techniques involve operation on one or more of the three fundamental characteristics: – Amplitude – Frequency – Phase Department of CE/IT

5. Demodulation At the sending end of the channel, the data to be transmitted is used to modulate the carrier signal. At the receiving end, the opposite process must occur to recover the original data. This process in known as demodulation. ModulationDemodulation User data User data Carrier Modulator Demodulator Department of CE/IT

6. Amplitude Modulation (AM) In amplitude modulation, the amplitude of the constant frequency carrier is varied or modulated by the amplitude of the data signal. The amplitude of the modulating signal is not constant; it changes with the data content. The frequency and phase of the carrier remain the same, only the amplitude changes to reflect variations in the information content. Department of CE/IT

8. Advantages It is easy to implement and demodulate It provides a straightforward method of getting signals into distinct frequency bands. Mathematical analysis of the AM process is comparatively simpler. Standard electronic instrumentation can be used for testing and repair of AM systems. Department of CE/IT

9. Disadvantages If some sort of electrical noise is picked up by the channel, then it results in corruption of AM signal. Power is not efficiently used by AM signals. Department of CE/IT

10. Frequency Modulation (FM) In frequency modulation, the frequency of the constant frequency carrier is varied or modulated by the frequency of the information signal. In frequency modulation, frequency varies, amplitude and phase remain constant. Department of CE/IT

12. Application Broadcasting Magnetic Tape Storage Sound Radio Miscellaneous Department of CE/IT

13. Disadvantages It requires a much wider bandwidth than the original signal. The circuitry for modulating and demodulating is much more complicated than for AM. Department of CE/IT

14. Phase Modulation Phase modulation (PM) is a form of modulation that represents information as variations in the instantaneous phase of a carrier wave. The phase modulated (PM) signal is similar to that of an FM signal, so angle modulation. PM and FM both are known as angle modulation. Department of CE/IT

16. The End …. Thank You … Department of CE/IT