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Signal Processing Lab

 In sem VI we were introduced with signal processing lab for which the pre requisite was Signals and Systems lab which was done in sem V. The codes that we did in signal and processing lab were now implemented on DSP board which were mostly in c language. Prof. Talele were incharge to conduct both the labs. On very first day zip file was shared with us which included all the codes to be implemented.  In DSP lab sir asked us to maintain a small note book which was shared between two students. Whenever lab were conducted sir used to give us some task to perform which were different from others and were checked at the end. This practise helped all of us to preform our task sincerely and if the given task was not over   in that lab session we were asked to perform it after college hour, so anything was not pending for next week. As our experiment were different form others, it was a learning experience for all of us. For 1 st  few practical we w...
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Simulator

In this lab, we carried out different digital modulation techniques like BPSK, DPSK and QPSK using CCS simulator. BPSK conveys data by changing, or modulating, two different phases of a reference signal. In DPSK, there is no absolute carrier phase reference, instead transmitted signal is itself used as phase reference. In QPSK two bits are modulated at once, selecting one of four possible carrier phase shifts.
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Linear filtering using OAM/OSM

In this lab session we performed Overlap add method  and Overlap save methods operation by  taking long input sequence x(n). This long sequence was decomposed into small L point sequences such that N=L+M-1. These N point sequences where zero padded in OAM and using fft corresponding x[k] was found.these all x[k] were added to obtain the output on CCS. 1. In OAM method, the values which get overlap were added together. 2. In OSM method, the values which get overlap were discarded.  The OAM and OSM methods divide the input signal into smaller lengths and filter output (FFT) of such smaller length signal is calculated. The overlapped portion is added in case of OAM and discarded in case of OSM. The resultant output is the output of the whole input signal.The aim of this experiment was to perform filtering of long data sequence using overlap add method and overlap save method.
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DFT and FFT

We performed DFT for 4 point as well as for 8 point .We understood the facts learnt in theory. It is very important to understand the working of the code.We performed DFT and Inverse DFT , Calculation of Energy for FFT and Inverse FFT .From this i understood that As the length of input signal increases:- (i) Frequency spacing decreases (ii) Approximation error in representation of spectrum decreases (iii) Resolution increases. We tested it for some inputs and verified the output by analytical method. DFT assumes input as periodic and gives  periodic output sequence ,energy of the signal in time and frequency domain is equal. If we do zero padding then number of points increases hence resolution and quality of spectrum increases while the approximation error ,frequency spacing decreaces.
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Correlation

  Convolution is a very important process in analog as well as Digital signal,time signal or frequency signal.it gives us what will happen if two signals are shifted and mixed together.  In this lab session we performed a correlation operation of two sequence using TMS 320f28335.correlation describes the mutual relationship which exists between two or more things.if we want to know how much similarity exists between the signals 1 and 2, then we need to find out the correlation of Signal 1 with respect to Signal 2 or vice versa.we have two kinds of correlation: autocorrelation and cross-correlation.Then we tried to create a logic for it and after building the logic we coded the logic in c language.after runnig the code we got the outputs.we performed Carl perason correlation coefficient calculation using formula .
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Convolution

 In this lab session we performed  linear convolution and circular convolution of two sequences using TMS 320F28335 DSK Kit, First i write the code for circular  convolution using FFT and Linear Convolution using FFT in c language and using Code composer studio tool i am able execute the file also loaded and run directly on the dsp processors.from this I learn that circular convolution and linear convolution are a mathematical operation that represent a signal passing through Linear and time-invariant system. Convolution is used to find out the output of an LTI system.If the response of the system to the impulse signal is known(h(t) or h(n)),then the response to any other input to the system can be found out by convolving the input signal with impulse response. Convolution is a very important process in analog as well as Digital signal,time signal or frequency signal.it gives us what will happen if two signals are shifted and mixed together.
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LED BINARY COUNTER

In this lab session  we get a hands on experience on the DSP board of TI, we understood the basics of flash programming and proper use of JTAG. We use TMS320f28335 for making a LED Binary counter. Flash programming was introduced as needed when we had to detatch the JTAG from computer. Flash programming is used to make stand alone systems. Once the flash programming was done, even after the power was removed and external power source was used, the DSP board still contained and ran the same code, hence we saw that if we want the same code to run on the Board, without interruptions then Flash programming is our go-to choice. For this experiment, you should know binary form. There are  four LEDs on the DSP board. We had to blink it from 0 to 15 in binary. For if it is 0 then, no LED will blink and for 1, it should be 0001 and so on in binary form.
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