PowerPoint PresentationData, Information and SignalsCapturing SoundSlide 4Capturing Sound (cont’d)Slide 6Slide 7Representing SpeechRepresenting Speech (cont’d)Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Representing AudioSlide 17Slide 18Slide 19Slide 20Character Mapped ImagesRepresenting ImagesScanned ImagesSlide 24Bit-mapped ImagesBit Mapped Image ExampleSlide 27Transform Image RepresentationSlide 29Slide 30Slide 31TransformsVideoVideo (continued)InterlacingSlide 36Slide 37NTSC VideoHDTV VideoVideo Compression CodingSlide 41Copyright 2001, S.D. Personick. All Rights Reserved1Telecommunications Networking ITopic 2Data and Information, and Signals that Represent Data and Information Dr. Stewart D. PersonickDrexel UniversityCopyright 2001, S.D. Personick. All Rights Reserved2 Data, Information and Signals•Sound: speech, audio, represented, modeled and simulated•Text and Images: character mapped, scanned, bit mapped, transform representations•Video: real and animated, frame-by-frame, interframe compression codedCopyright 2001, S.D. Personick. All Rights Reserved3Capturing SoundCopyright 2001, S.D. Personick. All Rights Reserved4Capturing Sound•Sound takes the physical form of an acoustic wave... i.e., variations in pressure vs time and space... that travels through a compressible physical medium such as air (~1090 feet/second… ~332 meters/second)•A microphone (transducer) converts locally received pressure variations into a varying voltage/current that represents the soundCopyright 2001, S.D. Personick. All Rights Reserved5Capturing Sound (cont’d)•The varying voltage waveform that represents the captured sound is communicated to another location using one of many possible communication system technologies •The received varying voltage waveform is not an exact replica of the transmitted voltage waveformCopyright 2001, S.D. Personick. All Rights Reserved6Capturing Sound (cont’d)•The received varying voltage waveform is used to “drive” a speaker (transducer) which produces a new acoustic wave (sound) that is perceived as an approximation of the original sound•Does the reproduced acoustic wave “sound” like the original acoustic wave?Copyright 2001, S.D. Personick. All Rights Reserved7Capturing Sound (cont’d)•The received varying voltage waveform is used to “drive” a speaker (transducer) which produces a new acoustic wave (sound) that is perceived as an approximation of the original sound•Does the reproduced acoustic wave “sound” like the original acoustic wave? The answer depends upon the applicationCopyright 2001, S.D. Personick. All Rights Reserved8Representing SpeechCopyright 2001, S.D. Personick. All Rights Reserved9Representing Speech (cont’d)•Speech is one of the most important analog signals•Representation qualities include:-Intelligibility: Can I understand what you are saying? Can I build a machine that responds properly to what you are saying?-Naturalness: Does it sound like face-to-face communication? Can I identify the speaker? -Comfort: Is it pleasant to listen to?Copyright 2001, S.D. Personick. All Rights Reserved10Representing Speech (cont’d)•Traditional telephone quality speech: 3 kHz high frequency cutoff, small amounts of noise and echo•AM radio quality speech: 5 kHz high frequency cutoff, varying amounts of noise and interference•FM radio, TV, other high quality speech: 10 kHz+ high frequency cutoff, barely perceptible noise and interferenceCopyright 2001, S.D. Personick. All Rights Reserved11Representing Speech (cont’d)•Traditional telephone quality speech: 3 kHz high frequency cutoff, small amounts of noise and echo [ ~32 – 64 kbps ]•AM radio quality speech: 5 kHz high frequency cutoff, varying amounts of noise and interference [~64 – 128 kbps]•FM radio, TV, other high quality speech: 10 kHz+ high frequency cutoff, barely perceptible noise and interference [~128 – 324 kbps]Copyright 2001, S.D. Personick. All Rights Reserved12Representing Speech (cont’d)•Compressed speech-Uses digital signal processing to remove redundancies in the original speech signal. -This typically impacts on the naturalness and comfort associated with the speech signal produced at the receiving end of a link, but (hopefully) still provides intelligibilityCopyright 2001, S.D. Personick. All Rights Reserved13Representing Speech (cont’d)•Compressed speech [~8 – 16 kbps]-Uses digital signal processing to remove redundancies in the original speech signal. -This typically impacts on the naturalness and comfort associated with the speech signal produced at the receiving end of a link, but (hopefully) still provides intelligibilityCopyright 2001, S.D. Personick. All Rights Reserved14Representing Speech (cont’d)•Modeled and simulated speech-Uses a model of the vocal tract to generate sounds that are perceived as intelligible speech -Real speech is captured by estimating the vocal tract parameters (that vary relatively slowly in time v. the sound speech waveform itself). These parameters are stored and/or transmitted, and used to recreate the captured speech.Copyright 2001, S.D. Personick. All Rights Reserved15Representing Speech (cont’d)•Modeled and simulated speech [~1.2 – 4.8 kbps]-Uses a model of the vocal tract to generate sounds that are perceived as intelligible speech -Real speech is captured by estimating the vocal tract parameters (that vary relatively slowly in time v. the sound speech waveform itself). These parameters are stored and/or transmitted, and used to recreate the captured speech.Copyright 2001, S.D. Personick. All Rights Reserved16Representing Audio•Audio signals, like music typically demand a high accuracy of representation to meet users’ expectations >10 kHz high frequency cutoff <100 Hz low frequency cutoff low noise and distortion•A typical audio system specification includes a 20-20,000 Hz “frequency response”Copyright 2001, S.D. Personick. All Rights Reserved17Representing Audio•Audio signals, like music typically demand a high accuracy of representation to meet users’ expectations >10 kHz high frequency cutoff <100 Hz low frequency cutoff low noise and distortion•A typical audio system specification includes a 20-20,000 Hz “frequency response” [128 kbps – 1 Mbps]Copyright 2001, S.D. Personick. All Rights Reserved18Capturing Analog Images•Use a camera or scanner (transducer) to produce a signal or a set of