Companding, Types of Signaling_Tabique, Engracia.pptx

Companding, Types of Signaling.pptx

1. Companding : A law and U law James Ryan A. Tabique

2. Outline 02-11- 2021 Good Education,Strong Nation 2 Introduction What is companding in PCM? A- Law Companding Numerical problem on A- Law Companding μ- Law Companding Numerical problem on μ- Law Companding Importance of Companding

3. Introduction 02-11- 2021 Good Education,Strong Nation 3 Linear quantizing in PCM systems has two major drawbacks: The uniform step size means that weak analog signals will have a much poorer SNR Q than the strong signals. range Systems of wide dynamic ending bits and consequently require wide many system bandwidth.

4. What is companding in PCM? 02-11- 2021 Good Education,Strong Nation 4 Companding: Companding is the process of compressing and expanding the signal while encoding and decoding process. Non- Uniform/nonlinear encoding and decoding is called Companding .

5. What is companding in PCM? compression No compression Output V V (max) V (min) Input/output characteristics which provides Compression V i (max) V i (min) Input V i 02-11- 2021 Good Education,Strong Nation 5

6. A- Law Companding Compressor Characteristics is piecewise, made up of a Linear segment for low- level inputs and Logarithmic for High level inputs. The logarithmic compressor standard used in European Telecommunication systems is given below: A s 02-11- 2021 Good Education,Strong Nation 6 1 A  1  ln( A s ) 1 sgn( s )  s  1  1  ln( A ) A y    sgn( s )  s    1  ln( A ) where 'A' is choosen as 87.56

7. A- Law Companding 02-11- 2021 Good Education,Strong Nation 7 s  normalized input y  normalized output A  87.56(A parameter that is selected to give the desired compressor characterstic.) The SIGN function returns - 1, 0, or +1 when the Numeric Expression value is negative, zero, or positive respectively

8. Numerical problem on A- Law Companding An A law Quantizer has an input range - 5v to +5v.For A=100, find the output of the Quantizer for the inputs of 30mv and 3v. for 30mV, Normalized absolute input |x| = 0.03/5 = 0.006 which lies in the range (0,0.01) i.e. < |x| < 1/A hence the normalized o/p is obtained by: y= (100  0.006) (1+ln(100)) 0.6 5.605   0.107 A s A sgn( s )  s  1 1  ln( A ) 02-11- 2021 Good Education,Strong Nation 8 Normalize value of our signal

9. Numerical problem on A- Law Companding (1+ln(100))  5.094 5.605  0.909 Now the actual o/p Y = 0.107  5 = 0.535 V for 3V, Normalized absolute input |x| = 3/5 = 0.6 V which lies in the range (0.01,1) i.e. 1/A < |x| < 1 hence the normalized o/p is obtained as: y= (1+ln(100  0.6)) Now the actual o/p Y= 0.909  5 = 4.545 V A 1  ln( A s ) sgn( s ) 1  s  1 1  ln( A ) 02-11- 2021 Good Education,Strong Nation 9

10. μ- Law Companding The Compressor characteristics are continuous and is given by the following function: The logarithmic compressor employed in American and Canadian Telecommunication systems:  1  ln(  s ) 02-11- 2021 Good Education,Strong Nation 10 sgn( s ) s  1, y  1 y   ln(1   )  here   A parameter that is selected to give the desired compressor characterstic.

11. μ- Law Companding 02-11- 2021 Good Education,Strong Nation 11 where : s  normalized input y  normalized output The SIGN function returns - 1, 0, or +1 when the Numeric Expression value is negative, zero, or positive respectively

12. Numerical problem on μ- Law Companding sgn( s ) 1  ln(  s ) y  ln(1   ) An μ law PCM Quantizer has an input range - 5v to +5v.For μ =100, find the output of the Quantizer for the inputs of 30mv and 3v. for 30mV, Normalized absolute input |x| = 0.03/5 = 0.006 hence the normalized o/p is obtained as y = 1+ln(100  0.006)  0.4891  0.1059 ln(1+100) 4.615 02-11- 2021 Good Education,Strong Nation 12 Now the actual o/p Y  5  0.1059  0.5299 V

13. Numerical problem on μ- Law Companding for 3V, Normalized absolute input |x| = 3/5 = 0.6 V which hence the normalized o/p is obtained as: y = 1+ln(100  0.6)  4.1108  0.8907 ln(1+100) 4.615 02-11- 2021 Good Education,Strong Nation 13 Now the actual o/p Y  5  0.8907  4.4538 V

14. Comparison between A-Law and µ - Law 0.8 0.2 0.4 0.6 0.8 1.0   255 1.0 A  87.56 s y 0.6 0.4 0.2 02-11- 2021 Good Education,Strong Nation 14

15. Importance of Companding 02-11- 2021 Good Education,Strong Nation 15 There is a wide array of audio transmission systems that employ A- law and/or µ- law Companding for data rate reduction with good audio quality. The compression achieved by both A- law and µ- law coding is the result of utilizing the logarithmic characteristics of the human auditory system, where fewer bits of precision are required for larger signals than smaller ones. The logarithmic transfer function is implemented with a piece- wise linear approximation.

16. References 02-11- 2021 Good Education,Strong Nation 16 Lathi B.P. “Modern Digital and Analog Communication Systems” Oxford Publications, Fourth Edition Taub H.,Schilling D.L.,Saha G. “Taub’s Principle of Communication Systems”, McGraw- Hill, Third edition Mutagi R.N. “Digital Communication” Oxford Higher Education

17. TYPES OF SIGNALING BSECE Communications 2 Engracia, Julius Caesar

18. LEARNING OBJECTIVES Define Signaling: Understand the basic concepts and definitions associated with signaling in electronic communications. Differentiate Between Analog and Digital Signaling: Compare and contrast the characteristics, advantages, and disadvantages of analog and digital signaling methods. Explain Baseband and Broadband Signaling: Describe the differences between baseband and broadband signaling, including their applications and limitations. Identify Pulse Signal Types: Recognize various pulse signal types and their significance in digital communications. Discuss Applications: Explore real-world applications of different signaling types in telecommunications, networking, and broadcasting.

19. WHAT IS SIGNAL? Signaling refers to the methods used to convey information over a communication medium. It is crucial for the effectiveness of communication systems, as it determines how data is transmitted, received, and interpreted. Types: Analog, Digital, Baseband, Broadband, Pulse. Key Features: Frequency, amplitude, phase, and modulation.

20. ANALOG SIGNAL a time-varying signal that may contain an infinite number of values within a continuous scale. In electronics, the voltage, current, or frequency of the signal can be modified to define the information. Analog signals are determined by the response to change of physical quantities, such as light, sound, temperature, position, pressure etc. Characteristics: Smooth, continuous waveforms. Advantages: Better resolution, simple design. Disadvantages: Prone to noise and distortion.

21. ANALOG SIGNAL Basic analog electronic components are resistors, capacitors, inductors, diodes, transistors, and operational amplifiers (op amps).

22. DIGITAL SIGNAL a signal that can be expressed as a sequence of discrete values. It can only take one value from a finite set of possible values at a given time. Digital signals are used in digital electronics, such as computing and data transmission devices. Characteristics: Pulse-like, non-continuous. Advantages: Less noise, better compatibility with modern systems. Disadvantages: Requires higher bandwidth, more complex systems.

23. DIGITAL SIGNAL Digital circuits implement components such as logic gates or more complex digital ICs.

24. Feature Analog Digital Signal Type Continuous Discrete Noise Resistance Low High Bandwidth Wide Narrow (efficient) Applications Radio, analog TV Internet, digital TV COMPARISON OF ANALOG AND DIGITAL

25. BASEBAND TRANSMISSION a method of transmission where a single signal is either transmitted or received in the type of discrete pulses of a single frequency across a communication medium like a cable. The baseband signal's frequency is not changed, and the signal's bandwidth is almost 0. Baseband systems do not use frequency shifting, so only one signal uses the entire bandwidth of the system at once. Therefore, any remaining bandwidth is wasted.

26. BASEBAND TRANSMISSION ADVANTAGES Advantages It has a simple structure. It is easy to install. Its maintenance is simple and easy. It has low-cost installation. Disadvantages It may be only utilized for voice and data. It has a short coverage and a limited range. It works only on a limited distance.

27. BROADBAND TRANSMISSION Broadband Transmission sends data in the form of analog signals, allowing signals to be sent at multiple frequencies simultaneously. This broadband transmission is unidirectional. In other words, the data is only transmitted in one direction at the same time. As a result, it may send or receive data but not perform both operations at the same time.

28. BROADBAND TRANSMISSION ADVANTAGES Advantages The main advantage of broadband transmission is its speed. It offers a fast speed for data transmission. It has a large bandwidth provision for data transmission. The data transmission may take place for a large distance. Disadvantages It needs some extra hardware for data transmissions like Multiplexers and De-multiplexers. The broadband transmission maintenance and cost are high.

29. BASEBAND VS BROADBAND

30. BASEBAND LAN VS BROADBAND LAN Baseband: Total bandwidth of I to 100Mbps is provided over coaxial cable, UTP, STP, or fiber optic cable. Distance limitations depend on the medium employed and the specifics of the LAN protocol. Broadband: Individual channels offer bandwidth of 1 to 5 Mbps, with 20 to 30 channels typically supported. Aggregate bandwidth is as much as 500 MHz.

31. PULSE SIGNAL TYPES The “frequency” is the number of electrical signal vibrations that are repeated per unit of time, and “Hz (hertz)” is a unit that indicates the number of vibrations per second. The (square) waves of electrical signals that occur in such a short period of time and have a certain width are called “pulses” or “pulse signals.”

32. CLASSIFICATION BY COUNT

33. CLASSIFICATION BY DURATION (WIDTH)

34. CLASSIFICATION BY INTERVAL

35. APPLICATIONS Stepper motor Servo motor