Amplitude Modulation - Paper
ANALOG COMMUNICATION LAB
Amplitude Modulation
Date: 4th February 2013
Submitted By ADARSH V R AKHIL KRISHNA R ANANTHU R KRISHNAN ARUN KOSHY T B100291EC B100125EC B100256EC B100091EC S6 ECE Batch: A
Contents
1 Introduction 2 Theory 3 Principles and Circuits Used 4 Design 5 Observations and Results 6 Conclusion 3 5 8 15 21 23
2
Chapter 1
Introduction
Today,communication has entered into our daily lives in so many different ways that it is very easy to overlook the multitude of its facets.From the radios and televisions to the mobile phone in our hand,all are capable of providing us with rapid communication from every nook and corner of the world.In the most fundamental sense,communication deals with transmitting and receiving information from one point to another through a channel. But we can’t transmit information as such from one place to another.The message signal is needed to undergo a process called modulation before being transmitted due the following reasons: 1. To send a signal over long distance, it requires more energy.Energy and frequency are related by the Planck’s formula E = hν (1.1)
where E = energy of the signal h = Planck’s Constant ν = frequency of the signal So when the frequency is low,energy will be obviously low.To increase the energy of the signal, we have to use a high frequency signal,which is done by modulation. 2. To decrease the antenna height.We know that for transmitting a signal of wavelength λ ,the antenna height must be λ/4.So if we want to send 1 Hz ( λ = 3 × 108 m)signal using an antenna, its height must be 3
75,000 km. It is impossible to build such a huge antenna.Suppose ,if the same signal is modulated to some high frequency say 88 MHz (λ = 3.4m), antenna height needed is 0.8522 m only which is quite easy to construct. Thus, we can see that the message signal which we have to send must be modulated before its transmission.In the process called modulation, we use a high frequency signal called
Amplitude Modulation
Date: 4th February 2013
Submitted By ADARSH V R AKHIL KRISHNA R ANANTHU R KRISHNAN ARUN KOSHY T B100291EC B100125EC B100256EC B100091EC S6 ECE Batch: A
Contents
1 Introduction 2 Theory 3 Principles and Circuits Used 4 Design 5 Observations and Results 6 Conclusion 3 5 8 15 21 23
2
Chapter 1
Introduction
Today,communication has entered into our daily lives in so many different ways that it is very easy to overlook the multitude of its facets.From the radios and televisions to the mobile phone in our hand,all are capable of providing us with rapid communication from every nook and corner of the world.In the most fundamental sense,communication deals with transmitting and receiving information from one point to another through a channel. But we can’t transmit information as such from one place to another.The message signal is needed to undergo a process called modulation before being transmitted due the following reasons: 1. To send a signal over long distance, it requires more energy.Energy and frequency are related by the Planck’s formula E = hν (1.1)
where E = energy of the signal h = Planck’s Constant ν = frequency of the signal So when the frequency is low,energy will be obviously low.To increase the energy of the signal, we have to use a high frequency signal,which is done by modulation. 2. To decrease the antenna height.We know that for transmitting a signal of wavelength λ ,the antenna height must be λ/4.So if we want to send 1 Hz ( λ = 3 × 108 m)signal using an antenna, its height must be 3
75,000 km. It is impossible to build such a huge antenna.Suppose ,if the same signal is modulated to some high frequency say 88 MHz (λ = 3.4m), antenna height needed is 0.8522 m only which is quite easy to construct. Thus, we can see that the message signal which we have to send must be modulated before its transmission.In the process called modulation, we use a high frequency signal called
Bibliography: 1. Simon Haykin, Communication Systems, 3/e, John Wiley and Sons, 1998 2. B.P. Lathi, Modern Digital and Analog Communication, 3/e, Oxford University Press, 1998. 3. A S Sedra and K C Smith , Microelectronic Circuits, Oxford University Press,1998 4. John G Proakis and Masoud Salehi, Communication Systems Engineering,Prentice Hall,1994. 24