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Pengolahan Sinyal Digital

Pengolahan Sinyal Digital

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Pengolahan Sinyal Digital

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  1. Pengolahan Sinyal Digital

  2. Perkembangan DSP Frequency Translate Digital Filter 512 Point FFT x(n) X(f) Frequency Translate Digital Filter 1024 Point FFT X(f) Dedicated hardware signal processor Data Select Filter Select Data Select FFT Select Data Select Data Buffers Digital Filter Data Buffers FFT Data Buffers x(n) X(f) Micro programmable signal processor hardware

  3. Programmable Signal Processor Controller Data Storage x(n) Programmable S P Input/ Output X(f) Distributed Programmable Signal Processor Data Storage Data Storage x(n) Input/ Output X(f) Data Communication Controller x(n) Input/ Output X(f) Processing element Processing element

  4. Perkembangan Processor DSP 60an

  5. Perkembangan Beaya (US$)

  6. What is DSP? • Digital operating by the use of discrete signals to represent data in the form of numbers • Signal a variable parameter by which information is conveyed through an electronic circuit • Processing to perform operations on data according to programmed instructions Which leads us to a simple definition of: Digital Signal processing changing or analyzing information which is measured as discrete sequences of numbers

  7. The advantages of DSP Versatility: • digital systems can be reprogrammed for other applications (at least where programmable DSP chips are used) • digital systems can be ported to different hardware (for example a different DSP chip or board level product) Repeatability: • digital systems can be easily duplicated • digital systems do not depend on strict component tolerances • digital system responses do not drift with temperature Simplicity: • some things can be done more easily digitally than with analogue systems

  8. Converting analogue signals to digital

  9. In the process of measuring the signal, some information is lost.

  10. Alising

  11. The high frequency signal is sampled just under twice every cycle

  12. The high frequency signal is sampled twice every cycle

  13. Antialising

  14. The Impulse respons of the reconstruction filter has a clasic : sin (x)/ x shape

  15. Frequency resolution

  16. Quantisation

  17. An analogue signal which is held on the rising edge of a clock signal

  18. A real DSP system suffers from three sources of error due to limited word length in the measurement and processing of the signal: • limited precision due to word length when the analogue signal is converted to digital form • errors in arithmetic due to limited precision within the processor itself • limited precision due to word length when the digital samples are converted back to analogue form These errors are often called 'quantization error'

  19. Block Diagram

  20. Spectrum

  21. Sistematika Disain DSP Transformasi Z Analisis Diskrit Finite Regst DSP Linier Sistem Diskrit Infinite Impulse Respons Digital Filter Finite Impulse Respons Digital Filter Multirate DSP FFT DFT Adaptive Filter Disain Digital signal Processing

  22. Methodology System Design Step 1 User/customer driven Develop system level Signal processing Non signal processing System level documentation Requirement specification Interface design specification System Requirements Defiition Step 2 Signal Analysis Step 3 Define input signal Types Parameter Noise sources & distribution Data rates Sisgnal Processing Design Step 4 Resource Analysis Dev SP graphs for each procss Specify primitive operation Initial partitioning Arithmetic analysis Iterative process Results in architecture approach Acceptable No Yes Step 5 Configuration Analysis Final partitioning of process Memory, Control, bandwidth Acceptable Perform resource analysis Configuration HW No Yes

  23. HDTV - Jepang

  24. Infinite Impulse Response (IIR) Disain prosedure: • Menggunakan formula disain untuk analog yaitu penentuan pole dan zero pada Butterworth, Chebyshev dan Elliptic • Formula transformasi bidang frekuensi • Transformasi bilinier, dg pemetaan pole pada bidang-s ke pole bidang-z

  25. LPF Digital dan Analog

  26. HPF LPF BSF BPF

  27. Keuntungan Digital Filter • Stabil thd Panas: Perubahan temperatur pada R,C dan L tidak terjadi, karena menggunakan Adders, multipliers, dan sift registers • Presisi: akurasi, stabilitas, respons frekw.dg menggunakan processor register. • Mudah Penyesuaian: dapat lebih tepat dan dapat diprogram sesuai kebutuhan • Kelipatan: dapat dilipatkan untuk mendapatkan rangkaian yang lebih efisien.

  28. Kerugian Digital Filter • Bandwidth terbatas: dengan hasil proses sampling dari analog ke digital (A/D converter), bandwidth signal terbatas setengah dari frekuensi sampling. • Keterbatasan register: implementasi sistem waktu diskrit pada perangkat keras dengan penggunaan khusus terjadi penurunan performance, karena terbatasnya jumlah bit.

  29. Sistem Waktu Diskrit

  30. Fungsi Transfer orde-N Inverse Z-tranforms

  31. Lowpass Butterworth Filters

  32. Respons Frekuensi

  33. Analog Lowpass Chebyshev Filter

  34. Analog Lowpass Elliptic Filter

  35. Transformasi Band Frekuensi Design normalized analog filter of order N Perform Freq. Band Transformation analog to analog Desired Digital Filter Digitize filter Design normalized analog filter of order N Desired Digital Filter Perform Freq. Band Transformation analog to analog Digitize filter

  36. Transformasi Bilinier

  37. Pemetaan Frekuensi dari transformasi bilinier

  38. Digital Lowpass Filter Disain