INTRODUCTION TOCOMMUNICATION TECHNOLOGIES

COMMUNICATIIN TECHNOLOGIES

1. Course name: basic Electronics engineering Course code : EC 1001 lecture series no : 01 (one) Credits : 3 Mode of delivery : online (Power point presentation) Faculty : Email-id : PROPOSED DATE OF DELIVERY: B.TECH FIRST YEAR ACADemic YEAR : 2022-2023 1 Dr Amit Rathi

2. Session outcome “Introduction to communication system & Analog Modulation Scheme” 2 Dr Amit Rathi

3. Assessment criteria’S Assignment quiz END TERM EXAMINATION 3 Dr Amit Rathi

4. PROGRAM OUTCOMES MAPPING WITH CO4 [PO1] [ PO.1]. Engineering knowledge: Demonstrate and apply knowledge of Mathematics, Science, and Engineering to classical and recent problems of electronic design & communication system . 4 Dr Amit Rathi

5. Communications 5 Communications Transfer of information from one place to another. Should be efficient, reliable and secured. “A communication system is a process of conveying information from a source to a destination” Communication system Components/subsystems act together to accomplish information transfer/exchange “An electronic communication system is transferring information using an electrical field as a mean of signal ” 5 Dr Amit Rathi

6. R equire m en ts 6 Rate of information transfer The rate of information transfer is defined as the amount of information that must be communicated from source to destination. It will determined the physical form and technique used to transmit and receive information and therefore determines the way system is designed and constructed Purity of signal received The received signal must be the same as the transmitted signal 6 Dr Amit Rathi

7. Simplicity of the system Any communication system must be convenient in order to be effective and efficient and easy to use Reliability Users must be able to depend on a communication system. It must work when needed and transmit and receive information without errors or with an acceptable error. 7 Requirements 7 Dr Amit Rathi

8. Communications System Diagram In f orm a tion Source and Input Transducer Transmitter Channel Recei v er Output T r a n s ducer 8

9. Communications System Diagram Information Source and Input Transducer Transmitter Channel Recei v er Output T r a n s ducer 9 Information Source: Audio, image, text, data Input Transducer: Converts source to electric signal Microphone Camera Keyboard

10. Communications System Diagram Information Source and Input Transducer T r a n s mitter Channel Recei v er Output T r a n s ducer 10 Transmitter: Converts electrical signal into form suitable for channel Modulator Amplifier

11. Communications System Diagram Information Source and Input Transducer T r a n s mitter Channel Recei v er Output T r a n s ducer 11 Channel: Medium used to transfer signal from transmitter to receiver. Point to point or Broadcast Wire lines Fiber optic cable Atmosphere Often adds noise / weakens & distorts signal

12. Communications Channels Wireline Twisted Pair Cable Waveguide Fiber Optics Wireless (radio): Transmission of electromagnetic waves from antenna to antenna KHz to ultraviolet Propagation characteristics vary with frequency Increasing bandwidth 12

13. Communications System Diagram Information Source and Input Transducer Transmitter Channel Receiver Output T r a n s ducer 13 Receiver Extracts an estimate of the original transducer output Demodulator Amplifier

14. Communications System Diagram Information Source and Input Transducer T r a n s mitter Channel Recei v er Output T r a n s ducer 14 Output Transducer: Converts electric signal to useable form Speaker Monitor

15. Baseband vrs Modulated Signal 15 Baseband Signal Base band signal is the modulating signal/ original information signal either in a digital or analog form (intelligent/message) in communication system Example: voice signal (300Hz – 3400Hz) Transmission of original information whether analog or digital, directly into transmission medium is called baseband transmission. Modulated Signal Modulated signal is baseband signal which its original frequency is shifted to higher frequency to facilitate transmission purposes Dr Amit Rathi 15

16. Block Diagram of Modulation Process 16 MO DU L A TI O N PROCESS Baseband signal Mo du l a t e d s i gn al C a r r i e r Dr Amit Rathi 16

17. Baseband Transmission 17 The need of baseband transmission: The concepts and parameter of baseband transmission are used in modulated transmission Performance of baseband transmission is used as the standard for comparing modulation techniques Baseband signal is not suitable for long distance communication because: Hardware limitation (eg: requires very long antenna) Interference with other waves Dr Amit Rathi 17

18. Modulation 18 Modulation – Process of changing baseband signals to facilitate the transmission medium Process of modulation Frequency translation such as AM, FM, PM etc Sampling and coding such as PAM, PCM etc Keying such as ASK, FSK etc Dr Amit Rathi 18

19. Types of modulation : Analogue modulations are frequency translation method caused by changing the appropriate quantity in a carrier signal Digital modulation is the result of changing analogue signal into binary ones by sampling and coding Keying modulations are digital signals subsequently modulated by the frequency modulation by using one or other analogue method 19 Modulation Dr Amit Rathi 19

20. Why Modulate? 20 Reduce noise and interference By using proper frequency where noise and interference are at minimum Increasing power is costly and may damage equipment Frequency Assignment For TV and radio broadcasting, each station has a different assigned carrier Multiplexing Combining several signals for simultaneous transmission on one channel by placing each signal on different carrier frequency Dr Amit Rathi 20

21. Why Modulate? Antenna Hight The height of the antenna required to transmit and receive radio waves is a function of wavelength of the frequency used. i.e. λ = c/f . At low frequency, λ is high and hence the height of the antenna should be more to transmit the signal (since ‘ λ’ is proportional to ‘h’). Therefore high frequencies are used to transmit the information which requires antenna of lesser height. Dr Amit Rathi 21

22. Why do we need Modulation/Demodulation? Example: Radio transmission M i c r oph o ne T r a n s mitter Electric signal, 20 Hz – 20 KHz V o i ce Antenna: Size requirement 1/ 4 wavelength efficient for for   transmission  or reception of  signals At 3 KHz: Antenna too large! Use modulation to transfer information to a higher frequency    c 3  10 8 f 3  10 3  10 5  100 km 22 July 1, 2010   /4  25 km Why Modulate?

23. Why Modulate? Increases the distance of transmission At low frequency radiation is poor and signal gets highly attenuated. Signal cannot be transmitted over longer distance. Modulation effectively increases the frequency of the signal to be radiated and thus increases the distance over which signal can be transmitted faithfully. Dr Amit Rathi 23

24. Analog Modulation There are 3 types of modulations: Amplitude Modulation (AM) Frequency Modulation (FM) Phase Modulation (PM)

25. Analog Modulation Amplitude Modulation: Amplitude of the carrier signal is varied in accordance with the amplitude of the message signal Frequency Modulation: Frequency of the carrier signal is varied in accordance with the frequency of the message signal Phase Modulation: Phase of the carrier signal is varied in accordance with the phase of the message signal

26. Amplitude Modulation Process in which the amplitude of a carrier signal is varied in accordance with the instantaneous amplitude of the message signal Frequency of carrier signal is much higher than frequency of modulating (message) signal