Signal Processing lab

After such a scoring and interesting signals and system I was quite interested to learn and enjoy in Talele sir's lecture. I was very much exicited even on the first day of the lecture and was prepared to learn new and important stuffs again as i did in signals and systems. The following week went into completing the DSPP books as Talele sir gave enough emphasis on notebook completion. I continued to complete my book throughout the semester which saved me from getting thrown out of the class.
In this journey of DSPP we had practical sessions too. These sessions were based on developing the code in C or MATLAB or CCS Simulink ,about all the concepts that we learned in the lecture time. We mainly used C to develop code which brushed our concepts of C. Due to limited number of practical slots and too many experiments in the list, many batches had to wait even after the college hours to complete it. I consider myself lucky because I wasn't one of those batches.

Along with the book completion and performing practicals, the experiments checking played a major role in making this semester more stressful. The experiments used to get checked if and only if we submit the code of the experiment and published blog on the blogger along with the handwritten journal. While doing mini projects or taking part in any technical competitions or performing in the festivals, we had to take out a considerable amount of time to write and publish the blogs. These published blogs were supposed to have at least 5 comments that too from students other than our college and our college but not from our class. Convincing our friends to read our blogs and get comment on it was a a quite difficult task. 

To make the DSPP subject more tiring, we had assignments on each chapter, had to be submitted in one week duration. All the assignments consisted of many sums which were long enough to take out considerable sweat from us, hence we could not give much importance on beautifying the content. We became pretty busy by end of March and in April because of such assignments. Though we were indirectly getting prepared for the final exam, at that time it was quite tedious.

Due to the limited time we could only get the introduction about the DSP processor but the first chapters were covered very nicely and thoroughly.

Though we were going from tremendous pressure, Talele sir made sure that learning is happening with entertainment. He did not spoil our cultural days by delivering a normal theory lecture but he showed some good quotes, images and meaningful things which he had collected from his personal whatsapp, facebook accounts and from other social media platforms.Also on our social week Talele sir took a nice group pic with our batch. In this course we also learned how to search for parents online, what to read and what not to read. We even searched IEEE papers and read them which established a foundation of good practices.We also learned how to read a patent and read many patents for the last experiment which was about the application of dsp.

In a nutshell I can say that it was a nice subject with a lot of work to do. Assignments trained us indirectly and practicals brushed our dusty C. A good course and a nice lifelong experience.

Application of DSP

In this patent document I read about controlling the audio input and modulate it with an equalizer. The input was taken through a microphone and the audio signal was converted into frequency domain signal. This signal was then divided into n parts which can be adjusted with the equalized input. These inputs modulate the amplitude of the input signal and increase or decrease depending on its necessity. These signals were then added together to form a equalized output signal.

Simulator

In this experiment we did carried out different phase shift keying techniques and line coding technique. But first we saw harmonic generation where we see different harmonics of wave and their interactions with each other.
We performed these experiments on CCS simulator generated the the values and plotted the values on QTplotter. BPSK, DPSK and QPSK are the types of phase shift keying we saw in these experiments. We realized the pros and cons of each of the techniques.
Secondly we saw line coding techniques like Manchester coding, Duo-binary encoding, Modified Duo-binary and Duo-binary with a precoder. Here too we realized how each coding technique affects inter-symbol interference.

ADC and DAC

In this experiment we used ADC-DAC of the DSP preocessor (TMS320). It has two 8 bit ADCs and one external 12 bit DAC. We generated different types of waves like sine wave, sawtooth wave and triangle wave. We did this by mapping the given bits to the function thus getting the requiered values.

We also used a 10k pot to see the changing voltage. There are two 8 bit ADCs to increase the speed of processing.

Sensor Interfacing

The real world application of the DSP is realized using sensor interfacing. We interfaced a handful of sensors and then saw their respective outputs on the DSO.

The Sensors were:

● LDR

● Temperature Sensor

● DHT 11

● SHARP sensor

● Optocoupler

● Microphone

LED Binary Counter

In this experiment we get a hands on experience on the DSP board of TI, we understood the basics of flash programming and proper use of JTAG.

In the given experiment, we utilized the on board LEDs to show the binary counting action happening, from 0-15 in binary.

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.

FFT

FFT is a proven faster method as compared to the DFT algorithm. Some of the similar complexities re-appeared in this code too (example - integration of complex numbers). Unlike the DFT, i could identify patterns in the butterfly diagram taught in the class. Formulating this pattern into a code format and making this code generic(for 4-point and 8-point) and efficient was the real highlight of this code. Though a generic N-point FFT code, still remains an ambitious task.

OAM / OSM

There were two parts in this experiment. The first one was to code for OAM method and the second was to code for OSM. By this date we had completed both of them in theory. hence we knew that to calculate FFT of a long length input signal is practically and mathematically a very difficult task because length of input signal increases the stages in the FFT algorithm. 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.

Correlation

In this experiment, we performed auto-correlation and cross-correlation. Apart from this we also used Carl Pearson Correlation Coefficient calculation using the provided formula and using FFT for the same.

Correlation is used for checking the similarity between two signals, and hence is an important tool. DSP is quite efficient in giving us the computational results.

Convolution

In this experiment, we performed linear convolution, circular convolution and linear convolution by circular convolution and both using FFT.

In circular convolution, we observed that the output signal was just the addition of elements of the linear convolution output. We can see that the linear convolution signal was overlapped to give circular convolution output. This is aliasing.

Therefore, we made the following conclusions from the above experiment:

● Length of linear convolution output signal= L+M-1

● Length of circular convolution=Max(L,M)

● Circular convolution gives aliased output