DIGITAL SIGNAL PROCESSING TOOLS VERSION 4.0

Transcription

1 (Digital Signal Processing Tools) Indian Institute of Technology Roorkee, Roorkee DIGITAL SIGNAL PROCESSING TOOLS VERSION 4.0 A Guide that will help you to perform various DSP functions, for a course in Digital Signal Processing. Pre requisite: Basic knowledge of DSP tools Introduction to LabVIEW programming language NOTE-Before performing the experiment, ensure that you have installed the DSP installer, or downloaded it from the link- or 1 P a g e

2 STEPS TO PERFORM DSP TOOLS: (Follow the instructions given here for proper operation of the same, and click the buttons only when required.) STEP 1: First of all login window will appear, login through a valid username and password or perform functions offline by clicking on "Work Offline". STEP 2: If you login through a valid username and password, you will see a Experiment History window where you can have access to your previous experiment reports. STEP 3: Then click on Perform New Experiment. STEP 4: From a choice of DSP functions select one, which is further divided into its subparts. STEP 5: Select a DSP function to perform. STEP 6: Press Generate Signal. Then select type of signal, frequency, phase and other added parameters to generate an input signal. 1) Press "Add to report", if performed experiment is to be included in the final report. 2) Press "Theory", to view the formulas used in function, press "Close window" to resume. STEP 7: Press Questionnaire, if you have done the experiment. This will open the questionnaire window. Answer the questions and submit to check result. STEP 8: Conclusion window will appear next. Comment remarks regarding the tools used or the experiment you performed. STEP 9: Last is the report window, take its print out or store. Press "Exit" to quit. Note for first time user: Before Performing any DSP tool user should get registered at Virtual Lab of Biomedical Instrumentation website or to get a valid Username & Password. 2 P a g e

3 HOME.. 4 Login Window. 4 Account Window 5 Experiment Window... 6 General DSP Functions Window 8 (a) Signal Statistics.. 8 (b) Power Spectrum. 9 (c) Convolution, Cross Correlation & Auto-Correlation.. 10 (d) Histogram 14 Transforms Window 15 (a) FFT (Fast Fourier Transform) (b) DCT (Discrete Cosine Transform) & DST (Discrete Sine Transform) (C) Hilbert Transform (d) Wavelet Transform.. 18 (e) Chirp-Z Transform Filters Window.. 19 (a) IIR (Infinite Impulse Response Filter). 20 (b) FIR (Finite Impulse Response Filter) (c) Window Function Implementation (d) Signal Filtering. 23 (e) Median Filter.. 24 Compression Window 25 Questionnaire Window.. 26 Conclusion Window 27 Report Window.. 28 Appendix P a g e

4 HOME Login Window- For first time users- Register on the virtual lab site following the linkhttp:// /vlab or to create an account for logging, this is to be done only once. After creating an account, login through the same username and password. For regular users- Since you already have a valid account, login through that Username and password. Click the "LOGIN button to proceed further. NOTE: Please enter a valid username and password. Biomedical Virtual Lab- To get access to Virtual biomedical lab portal. Live Chat- To chat with professionals for any guidance and support. 4 P a g e

5 Account Window- Account window will appear next. Press "Perform New Experiment" to perform DSP Functions or logout if required to do so. On this window, you can also have access to your previous experiment reports, only if you have performed any experiments earlier and submitted the report. *This window will not show up, if you are working offline. On clicking "Perform New Experiment an "Experiment" Window will appear with following functions- 1> General DSP Functions 2> Transforms 3> Filters & Windows 4> Compression 5 P a g e

6 Experiment Window- 1. Here the first block is of Instructions, which are given accordingly for each experiment. 2. Next is Experiment tab (left portion under the instructions), which contains all the DSP Function options. 3. Each DSP Function contain subdivisions which are given as follows- 1. General DSP Functions 1(a) Signal Statistics 1(b) Convolution 1(c) Power Spectrum 1(d) Histogram 2. Transforms 2(a) FFT (Fast Fourier Transform) 6 P a g e

7 2(b) DCT (Discrete Cosine Transform) 2(c) Hilbert Transform 2(d) Wavelet Transform 2(e) Chirp-Z Transform 3. Filters & Windows 3(a) IIR (Infinite Impulse Response) Filters 3(b) FIR (Finite Impulse Response) Filters 3(c) Window Implementation 3(d) Signal Filtering 3(e) Median Filter 4. Compression 4. Generate Signal is pressed to open a window, which is used to design the input waveform. a) The parameters like frequency, amplitude, phase, sampling frequency, simulation period and DC bias are adjusted to create a waveform, given in graph. b) You can also add noise to signal and check for aliasing as well. c) Then press the Import Signal to get the signal as input waveform on main window. 7 P a g e

8 5. There are 2 graphs (right portion under the instructions) as Input Signal and Output Signal. *Output signal is either enabled or grayed out according to requirement of the experiment 6. Add To Report- Press this button to add the experiment in the final report. 7. Questionnaire- This button brings up the new window of questions, which will be discussed later. 8. Go Back To Account- This button will take you back to the account window. 1>General DSP Functions- On selecting "General DSP Functions" tab from the DSP Functions Options, you will have to choose further from the given experiments- Signal Statistics, Convolution, Power Spectrum, and Histogram. 1(a) Signal Statistics Window Press the Generate Signal and select the input signal according to the Appendix 1and analyze the output parameters, which are shown in the form of table. 8 P a g e

9 This function calculates the following parameters: -Arithmetic Mean -Variance -Standard Deviation -Mode -RMS -Kurtosis -Skewness -Median -Minimum and Maximum of the input signal selected. 1 (b) Power Spectrum Window Press the Generate Signal and select the input signal according to the Appendix 1and analyze the output signal. There are two choices of power spectrum: single sided and double sided power spectrum. Corresponding to the choice, spectrum modifies its peaks at the selected frequency. Window is shown on next page. 9 P a g e

10 NOTE: The output is in normalized form. 1 (c) Convolution, Cross Correlation& Auto-Correlation Window When you select Convolution, you will further see the process options in which three options are given namely- convolution, auto-correlation and cross correlation. You can select any one of them to perform one by one. Convolution- In this experiment first you generate the signal 1 and then the signal 2 and set the parameters according to appendix1. These 2 signals will appear together in the input signal graph. Then select type of convolution i.e.-linear or circular. Then press the Convolute Signal to get the output (normalized output) in the output graph. 10 P a g e

11 Auto-Correlation- Select Auto-correlation from the options and generate input Signal. Then press the Generate Correlation to get the output in the output graph. Window is shown on the next page. 11 P a g e

12 Cross Correlation - In this experiment generate the signal 1 and then the signal 2 and set the parameters according to appendix1. These 2 signals will appear together in the input signal graph. Then press the Generate Correlation to get the output in the output graph. 12 P a g e

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14 1 (d) Histogram Window Generate the input signal and set the frequency, amplitude and phase of the signal according to the Appendix 1and analyse the output parameters. In this function a Gaussian noise function is added to input signal, whose standard deviation can be varied. The generated histogram is being plot with respect to bin values and amplitude. 14 P a g e

15 2>Transforms Window On selecting "Transforms" tab from the DSP Functions Options, you will have to choose further from the given experiments-fft, DCT/DST, Hilbert, Wavelet, Chirp-Z. 2(a) FFT (Fast Fourier Transform) Generate the input signal and set the frequency, amplitude and phase of the signal according to the Appendix 1and press the Show Waveform to get the output. NOTE: The output FFT is in normalized form. 15 P a g e

16 2 (b) DCT (Discrete Cosine Transform) & DST (Discrete Sine Transform) Window Generate the input signal and set the frequency, amplitude and phase of the signal according to the Appendix1. Then select the waveform you want to generate and analyze the output. This function evaluates the discrete sine and cosine transform (normalized) of the input signal and displays it in output graph. NOTE: The output is in normalized form. 16 P a g e

17 2 (c) Hilbert Transform Window Generate the input signal and set the frequency, amplitude and phase of the signal according to the Appendix 1and analyze the output. This Function evaluates the Hilbert transform of the input signal and displays it in the output graph. 17 P a g e

18 2 (d) Wavelet Transform Window Generate the input signal and set the frequency, amplitude and phase of the signal according to the Appendix 1and analyse the output. This function evaluates the wavelet transform of the input signal. From the drop down menu "Wavelet Type" select the type of mother wavelet such as Haar, db xx, bior xx etc. with level of decimations mentioned in adjoining numeric control Levels. 18 P a g e

19 2 (e) Chirp-Z Transform Window Generate the input signal and set the frequency, amplitude and phase of the signal according to the Appendix 1and analyze the output. This function evaluates chirp- Z transform of the input signal selected and displays it in the output graph. 3>Filters Window On selecting "Filters" tab from the DSP Functions Options, you will have to choose further from the given experiments- IIR Filters, FIR Filters, Window Implementation, Signal Filtering and Median Filter. 19 P a g e

20 3(a) IIR (Infinite Impulse Response Filter) Window In this experiment first select the type of filter -Lowpass (Only fpass1 and fstop1 will appear) -Highpass (Only fpass1 and fstop1 will appear) -Bandpass(fpass1,fstop1,fpass2 & fstop2 appear) -Bandstop(fpass1,fstop1,fpass2 & fstop2 appear) Set the frequencies according to the note provided and then select the design method from drop down menu, next set sampling frequency and finally the order of filter. Magnitude and phase response of the filter will be visible in the corresponding graphs. NOTE: Here the Input Signal represents MAGNITUDE RESPO NSE and Output Signal represents PHASE RESPONSE. db on?-indicates whether magnitude response is in decibels or is linear. 20 P a g e

21 3(b) FIR Filter Window In this experiment first select the type of filter, then any window from a drop down menu, next select the order of filter and at last set the frequencies according to the note given in the instructions. Magnitude and phase response of the filter will be visible in Input and Output graphs. 21 P a g e

22 3(c) Window Implementation Generate the input signal and set the frequency, amplitude and phase of the selected signal according to the Appendix 1and analyze the output parameters with the help offollowing description. Windowing of the input signal in correspondence to a number of windows is done by this function. To perform it select any type of window from thelist and see the output in windows implementation output graph. 22 P a g e

23 3(d) Signal Filtering Window Generate the input signal and set the frequency, amplitude and phase of the signal according to the Appendix 1and analyze the output parameters with the help of the following description. This function shows how filters can be used to reduce the effect of noise on a signal. To perform select the type of noise (for Gaussian noise set standard deviation), type of filter, its order and set the sampling frequency (higher than twice the frequency of signal). Input signal is a signal with added noise and filtered output shows distorted signal after being operated on by filter. NOTE: More is the sampling frequency more will be filtering it provides against noise. 23 P a g e

24 3(e) Median Filter Window Select the input signal and set the frequency, amplitude and phase of the selected signal according to the Appendix 1and analyze the output parameters. This function applies median filter to the input signal chosen, by varying the left and right rank of the median filter. 24 P a g e

25 4>Sample Compression Window Select the input signal and set the frequency, amplitude and phase of the selected signal according to the Appendix 1and analyze the output parameters with the help of following description. To perform this function select the type of compression method and press compression enable button to enable compression. And see the compressed signal in graph which will vary according to the type of compression method selected. 25 P a g e

26 Questionnaire Window When you have done the experiment, clicking the Questionnaire, another window appears which contains a number of questions in sequence. Attempt 10 questions in lineand see your result. 26 P a g e

27 Conclusion Window After you submit the result of questionnaire, this window gets closed and conclusion window appears. Comment remarks regarding the tools performed, which will appear in the final report. Click "Submit" and "View Report" to proceed to report section. 27 P a g e

28 Report Window The final report will appear in this window. Press "EXIT" to stop execution or print the report if required. 28 P a g e

29 Appendix 1 Gen e ral In st ru c t ion s to p erf o r m an y f u n c tion o r tool : - Select the input signal from a choice of Sine, Triangular, Square, Sawtooth, User defined and Formula based from a drop down menu. User-defined signal- To generate your own periodic signal by giving -> No. of harmonics -> Sampling parameters- Sampling Frequency Simulation period -> Order of harmonic -> Amplitude of harmonic Set the frequency by dragging the slider, or directly entering into the digital display next to it. NOTE- Do not set frequency more than 500Hz as maximum sampling frequency is 1000 Hz. 29 P a g e

30 Set amplitude by dragging slider, or entering directly into digital display. Maximum amplitude has been set to 100V. Set phase by dragging slider, or entering directly into digital display. Maximum phase has been set to 36 You can choose any tool provided in the graph palette for examining graph. Functions provided are- zooming a section of graph, shifting the graph etc "Add to report"- Click this button to add function in use to the final report. NOTE: Just performing a tool will not show your experiment in the final report. "Theory"- On clicking this button a small screen will appear giving the mathematical formulae of the function in use. NOTE: Remember to close window once opened to proceed further with experiment. 30 P a g e

31 Remember to close window once opened. 31 P a g e