1. Chapter Overview of Analog and Digital Technologies

5. MODULE Overview of Analog Technology

7. Analog Signals: The Basics Time Signal Frequency = Cycle/Second A typical sine wave Cycle Amplitude

11. Analog Digital Conversion 1 0 1 1 0 1 0 0 A to D Converters, Digital Signal Processors (DSP) etc.

12. Data Transmission Example Computer Modem Digital 0s and 1s Analog 0s and 1s Digital-to-Analog Modulation and vice versa

13. Voice Transmission Example Voice Carrier Wave AM Radio Transmission Analog-to-Analog Modulation

14. END OF MODULE

15. MODULE Frequency Spectrum and Bandwidth

17. Frequency Spectrum Low Frequency High Frequency Radio Frequency Coaxial Cable MHz Satellite Transmission Microwave MHz Voice KHz

23. Limiting Factors on Communication Speed Communication Speed Bandwidth Technology

25. Speed Dependency on Bandwidth and Technology Medium 1 example can be shielded twisted pair and medium 2 example can be fiber. Medium 1 Technology Medium 2 Higher Bandwidth

26. END OF MODULE

27. MODULE An Overview of Digital Technology

31. Digital Signal 1 0 1 1 0 1 0 0 Pulse Time Signal Strength Pulse Duration

32. Clock Speed and Pulse Duration Pulse Duration MHz

35. END OF MODULE

36. MODULE Digital-to-Analog and Analog-to-Digital Interfaces

38. Digital-to-Analog Interface Comp. Sys. 1 Comp. Sys. 2 Modem Modem Digital Serial RS-232C Digital Serial RS-232C Analog ITU V.90 POTS

39. Digital-to-Digital InterfaceA Comp. Sys. 1 Comp. Sys. 2 ISDN Adapter ISDN Adapter Digital Serial RS-232C Digital Serial RS-232C Digital ISDN

40. END OF MODULE

41. MODULE Overview of Digitization Of Information

43. Digital Information Processing Data Audio Image Video Digitized and Encoded Digital Transmission

46. END OF MODULE

47. MODULE Digitization Of Data

53. Unicode Advantage in WWW Transmissions Client Tamil Web Site Internet Explorer Browser retrieving Tamil pages on a client supporting Unicode. Tamil pages are transmitted in their binary encoded form. Site created using all the tools such as the MS-IIS.

54. Transmission of Tamil Pages as Images on WWW Client Tamil Web Site Internet Explorer Browser retrieving Tamil pages similar to images. Binary image transmission of Tamil pages. Web pages scanned and stored as images.

55. Using Downloaded Fonts to Host and Transmit Tamil Pages Client Tamil Web Site Internet Explorer retrieving Tamil pages. Site created with tools such as MS-IIS. Download and install the Tamil fonts. Binary encoded form. Bandwidth requirements are low.

56. END OF MODULE

57. MODULE Digitization Of Audio

59. Digitization of Audio: Pulse Amplitude Modulation (PAM) Audio 9 8 7 6 7 9 Digital Signals must further be encoded into binary signals for computer processing and transmission. Sampling Interval

61. Binary Encoding of Signals in Pulse Code Modulation (PCM) 9 8 7 6 5 6 1001 1000 0111 0110 0101 0110 The integer numbers have effectively been coded into zeros and ones. The ones and zeros now contain the audio information encoded in a form that could be processed by a computer. PCM

63. END OF MODULE

65. END OF MODULE

66. MODULE Audio Quality Vs Bandwidth in Audio Transmission

68. Factors Affecting Quality Number of bits used for binary encoding. Example: 4 bits allow 16 amplitude variations to be represented. 9 8 7 6 7 9 Sampling Interval

70. Problem Representation 79 68 57 46 57 79 1/8000 Seconds or 2X4000 samples per second 8 bits are used enabling 256 amplitudes to represent the human voice which is considered to be adequate.

73. Recording Quality and Bandwidth Requirement Demonstration

75. Audio Transmission In WWW Client Receive audio using Internet Explorer and a plug-in to receive the audio stream. Audio streaming requires compression. Real-time audio broadcast support using streaming server module. 28-56K bps Web Site

76. Delivery of Instruction Over the WWW Client Web Site Receive audio/video using Internet Explorer. Audio/Video streaming. Store streamed audio/ video using StreamCam. 28-56K bps

77. Internet Ramp Bandwidth Computation WWW A T1 line operating at approximately 1.354M bps can support approximately 47 connections in theory. In practice, 23 connections which is half of 47 can be supported with due consideration given to bandwidth bottlenecks.

78. Sampling Considerations In Communications Sender Receiver Digital audio transmission Adjust quality (sampling interval and bit representation) to suit bandwidth availability.

79. END OF MODULE

80. MODULE Quality Retention In Digital Transmission

82. Analog Audio Transmission Audio Prior to Transmission Audio with Interference Transmission Audio After Filtering

83. Passage of Analog Audio Over Analog Lines Analog Audio Analog Signals Analog Signals Analog Audio Telephone Telephone

85. Signal Passage in Digital Audio Transmission Encode Transmit Recreate Decode Audio Audio

86. A Sample Digital Audio Transmission Path Analog Audio Digital Audio ISDN Adapter ISDN Adapter Digital Audio Analog Audio Sound Card Sound Card ISDN Lines

89. Digitized Signal Passage Over Analog Lines Encode Transmit Recreate Decode Audio Audio Limited Sampling

90. A Sample Digital Audio Transmission Path Analog Audio Digital Audio Modem Modem Digital Audio Analog Audio Sound Card Sound Card Analog PSN

91. Audio Transmission In WWW Client Web Site Receive audio using Internet Explorer and RealAudio plug-in. Audio stream over analog/digital line. Real-time audio broadcast support using RealAudio streaming server module.

92. Digital Signal Processor DSP Digital Analog

93. END OF MODULE

94. MODULE Digitization Of Image

96. Digitization Of Image: Overview Pixel Horizontal Resolution Vertical Resolution

97. Digitization of the Letter L Number of bits determine the amount of information that could be stored.

106. END OF MODULE

107. MODULE Compression of Digitized Images

113. Image Transmission Considerations Sender Receiver Adjust image to suit available bandwidth. Adjustable features are as follows. - Resolution - Color depth Adjusting the size also reduces the bandwidth requirement because of a corresponding reduction in the number of pixels required to represent the image.

116. END OF MODULE

117. MODULE Digitization Of Video

127. END OF MODULE END OF CHAPTER