Chapter 1 Week 1 EE 341 Clark Lecture Notes - 1 april

Chapter 1 Week 1 EE 341 Clark Lecture Notes - 1 april - EE...

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EE 341 Discrete-Time Linear Systems – Week 1 Spring 2011 Page 1 Go over syllabus. Text reading assignment for this week: Chapter 1: Sec 3.2, 3.3, 4.1, 5, 7 (emphasis on discrete-time) Chapter 7: Sec 1, 3 (review on sampling lightly covered in EE 235) Why Digital Signal Processing (DSP)? 1. Provides perfect reproducibility and guaranteed (but not perfect) accuracy. 2. Often much less expensive than analog. 3. There are many discrete-time algorithms which are not available in continuous-time. Some Applications of DSP Military 1. sonar 2. radar 3. battlefield communications and acoustics Scientific 1. seismic data (first industry to go digital) 2. signal detection (SETI, project Phoenix) Health 1. speech enhancement for hearing aids 2. medical ultrasound 3. CAT scan, e.g. Prof. Atlas brain, Fall 2005, after brain hemorrhage. (Scan saved his life.) Industrial 1. Monitoring manufacturing processes via acoustic emissions Commercial/Entertainment 1. CD/DVD, Blu-ray players 2. iPod (uses mp3 or AAC from MPEG-4 standard) and other music and video players 3. Speech recognition 4. Communications (e.g. cellular phones, wireless networks, 3G data to handhelds) 5. MPEG, mp3 (MPEG-1, Layer 3) for video and music compression….
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EE 341 Discrete-Time Linear Systems – Week 1 Spring 2011 Page 2 Just a Few Examples Within mp3’s Encoding Block Diagram 1 DSP systems are now easy to design and test. For example: 1. MATLAB™ and lots of other tools to facilitate digital system design 2. Lots of existing code (e.g., FFTW, “Fastest Fourier Transform in the West” www.fftw.org ) 3. Relatively easy to implement new systems in C/C++ or Java 1 From http://www.iis.fraunhofer.de/EN/bf/amm/projects/mp3/flow.jsp (inactive), but now available, with more description, at http://wiki.hydrogenaudio.org/index.php?title=MP3 . For the history of MP3 development, see: http://www.iis.fraunhofer.de/en/bf/amm/mp3geschichte/ . Uncompressed Audio Uses DT System Theory Uses DFT Uses z -transforms, and linear phase Uses LTI system theory We won’t even try to describe Blu-ray’s use of DSP, since it is very extensive!
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EE 341 Discrete-Time Linear Systems – Week 1 Spring 2011 Page 3 Chapter 1 – Discrete-Time Signals and Systems We assume that we derived a discrete-time signal from a continuous time signal via sampling as in Section 7.1 of your text. (We will return to sampling theory and practice several times in EE 341.) Given () x t to be a continuous time signal, () x nT is the value of () x t at tn T . The discrete-time signal (or sequence)[] x n is defined only for n an integer. So if we derive [] x n from () f t by sampling every T seconds, where T is the sample period, we get: [] ( ) T xn xnT xt  We will not necessarily assume that [] x n is a discrete amplitude signal. A signal that is both discrete time and discrete amplitude is known as a digital signal. You will see these in later communications and signal processing courses. A well-known example of a digital signal is music on a compact disk. Or another example is a 2-dimensional signal like an image from a digital camera, 12 [, ] xnn . Or another common example is a time-indexed sequence of images
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Chapter 1 Week 1 EE 341 Clark Lecture Notes - 1 april - EE...

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