User:Priyasabu2003
From MariachiWiki
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Hi my name is Priya Sabu and I am a biomedical engineering major studying at Stony Brook University. I was born on July 4, 1988 and have lived in New York City since then. As a child I was very fond of puzzles and memory games. I loved struggling and spending hours solving difficult puzzles. I always want to challenge myself and try to do things that not most people cannot do whether it be in school or while I am with my friends. I was also and still am very mischievous. Being the oldest child I was spoiled, to some extent, and well known for being the kid who tried to flood her kitchen because she wanted to swim.
That pool really didn’t work out and a few years later I actually began learning how to swim. Since then I have spent many years swimming and was once part a swim team. Not only that but I am also fond of classical Indian dance which I have been learning since the age of 10. I’ve done many performances in the city particularly a yearly one at South Seaport. It’s more of a passion than a hobby. It relieves my stress and helps me be focused.
I enjoy reading books. Books, hot chocolate and a warm blanket make the perfect evening. One of my favorite books is Crime and Punishment by Fyodor Dostoevsky. Whenever I have free time to spend I am usually playing with my brother, shopping with my mom and sister or playing cards with my dad. I love spending time in the kitchen and experimenting with different recipes.
LINKS:
February 22, 2007
Today I was introduced to the
laboratory work in the
Basic Radio Processing Signals. I learned about the equipment
used and the main objectives in the laboratory. The lab is split into
two segments.One segment which, i learned about detects radio signals
using computers, antennas and a special software.
The other part of the lab uses a scintillator to detect High energy cosmic rays.
Both groups use different methods so that when one group gets a signal they can
verify the signal with another set of data. This helps make sure that
the data obtained isnt due to some disturbance in the air such as an airplane or radio station.
February 27,2007 Today we discussed the various components of the equipment used. There is an antenna, cable, splitter, reciever, audio signal and soundcard.There is a GPS system that consists of an antenna and a reciever. The GPS system uses several antennas for complete time and position reference. The antenna picks up radio waves and transmits and recieves radiowaves. It converts Electromagnetic waves into radio waves. Heinrich Hertz was the first to use antennas. An example of antenna use is in cellphones which, range from 900 to 1900 MHz. Radio, tv, broadcasting, point to point radio communication radar and space exploration also use antennas but these antennas are larger. This is because the higher the frequency the small the antenna. There are two types of antennas. Omni-directional, radiates equally in all directions and Directional, radiates in one direction either horizontal or vertical.The antenna patternor radiation is the relative strength of the radiated field with energy in terms of waves.They calculate the points by the use of sulfur.
But how does it work? What do they exactly do? and how is sulfur sent to such a distance to measure the wave?
The reciever is an electronic circuit that recieves a radiosignal from an antenna and converts the signal into sound, pictures navigation position, or information. The reciever that is used should be able to pick up certain frequencies. Generally the recievers that are used pick up the frequencies of wavelengths that the lab is interested in looking at. In this lab they use 2 recievers.
There was some mention of a Mixer and I'm still not particularly clear about what that is and how it works?
A GNU radio is a free software used for learning, building and replaying software radios. They do the processing in the software rather than a hardware.
I also learned how to set up a DAQ: 1. First I connect the antenna with the reciever 2. Then connect the audio output with the soundcard. 3. Finally open the control panel.
I also got a chance to explore WINRadio. I learned about the different features. For example how to change the frequency on the dial, tune to peak, record data, saving the data, how to listen to the AM radio and how to change the amount of frequency I want the antenna to pick up. The maximum was 120db.
March 1, 2007
Today's topic was MatLab- Signal Generation-Sounds. Some questions were also answered. The laboratory had a directional antenna only because if they have a omni-directional antenna the main problem they have is local interference of radio stations. Thus is it better to have a directional antenna for practical purposes. MatLab is a powerful simulation. It provides a numerical computing environment and programming language which was created by Mathworks. It's easy matrix manipulation, plotting of functions and data, use of algorithms, creation of user interface and interfacing with the program in other language. The software uses arrays to present matrices. It can do basic calculator calculations. In class I explored the MatLab software. I tried different mathematical commands provided by the instructor to learn about the different functions of MatLab. I also learned that in MatLab 1 x 10 will give you rows and 10 x 1 will give you columns. Also, explored the ones, zeros and rand function. When writing a row of numbers and changing certain numbers I learned how to use the index command. This command is useful when the series are really long and you have to assign alot of numbers. I also experimented with plotting a graph. Although at first me and my partner were a little confused we figured out a workable command. Particularly I liked the fact that you had so many options for the layout of the graph with the various colors, shapes and type of line.
Towards the end of class we were experimenting with the software and could not figure out whether or not is was possible to multiple each number in the matrix? For example [1 2 3] and the output would be [1 4 9].
March 6, 2007
Today we continued working with the MatLab software and experimented with a variety of different things such as amplitude and frequency, and resolution.Frequency is the number of cycles from 0 to 2pi. We were working with a sinusoid curve. y=sin(2*pi*f*t) When we changed the value of f to f=30 the graph was not continuous and not a sinusoid curve anymore. We learned that when we increase the value of f, t becomes larger. If the t is too large there are too many sinusoid curves in a smaller interval and thus its harder to visual the sinusoid curve in the same interval. When f is small the sinusoid curve can be visually seen on a graph on the same interval. When f=50 there are only 2 points per period. Then we tried to get more points per period so the graph would be useful. However the graph had so many points that it was still hard to read. Thus, you need a smaller interval and a smaller step. for example we used 0:1/8000:.01 Following this results in a sinusoid curve. When we tried this method we obtained the graph seen below.
This graph is easier to read because there are enough points per period that the sinusoid curve can be seen on the graph. (A sampling period is a step.)
After we learned how to manipulate the graph to achieve desired results we used MatLab to generate sound signals. We used the command: sound(sampledSignal, frequency). First we explored the sound differences by changing the time duration. When the sound interval was 10msec all we heard was a very rapid short beep. When we changed it to 2sec we heard the sound signal over a duration of 2 sec.
How does this help when you are studying sound signals acquired from the antenna? Does it make the signal more audible and useful?
Then we changed the amplitude. First by multiplying it by 0.5 and then by 2. The first resulted in a softer sound and the second one resulted in a louder sound. Another manipulation of the sound was by changing the frequency. When we lowered the frequency (8000/2) we got a low-pitch sound. Something like a base, deep sound. When the frequency was increased (8000*2) it resulted in a high pitch, sharper sound. This is because when the frequency is decreased the graph is spread out over the period. When the frequency is increased there is a shorter period and alot more is happening on the same interval.
How do you use MatLab to help you study the signals you obtain from your experiments?
March 8,2007
Today we continued our work on MatLab and further enhanced our experience with what MatLab can do. We worked on sound with an addition of noise. When data is collected for the laboratory to examine it also contains unnecessary noise that adds to the sound. When they do a simulation they need to account for a noise and need to filter that noise so they can hear the pure sound. Although the pure sound is hard to obtain they come very close to usuable data.
Addistive Noise and WAVE file processing in MatLab The Gaussian Noise is more likely to have a zero amplitude than a higher one. First we tried to generate a Gaussain Noise in a (3,5) array, using the syntax randn(3,5). It resulted in 15 random numbers. I think that these numbers are just any numbers that are stored in the computer and since the values of the array weren't specified random numbers showed up. Our second step was to generate a sound signal with the equation y(t)=sin(2*pi*830*t) with a sampling frequency Fs= 8000 Hz on a 2 second interval.Then we generated a noise signal of the same length by randn(1, length(y))* 0.1. To listen to it sound(randn(1,length(y))*0.1,8000) We heard alot of static and a buzzing sort of a sound. Then we compared two different commands: a)sound(sampledSignal, frequency) b)sound(sampledSignal+randn(1,length(y))*0.1, frequency) For (a) all we heard was pure sound. For (b) it was a combination of pure sound and noise. These sounds are different because one you can hear clearly and the other one you have a disturbance due to noise. To further understand how the noise factor works we played around with the commands and tried a)sound(sampledSignal+randn(1,length(y))*0.5, frequency) b)sound(sampledSignal+randn(1,length(y))*0.01, frequency) In (a) we noticed that the noise level got louder than the pure sound and for (b) the noise level was lower so pure sound was louder than the noise level. By changing the number we are multiplying by we are changing the amplitude of the noise. This can be useful when you are trying to listen to pure sound and by this method you can decrease the amplitude of noise so you can hear the pure sound better.
Then we continued by saving and loading WAVE files by using the syntax wavwrite(writeSignal, frequency, wavFileName). At first we had trouble writing a wav file because when we typed in the wavFileName it gave us an error. We later figured out that you have to put it in single quotes for the computer to read it as a name rather than a variable. Now to read the signal we used the syntax [readSignal, frequency]= wavread(wavFileName) This gave us the sampling frequency. Then we created two new wave files with frequency= 4000Hz and 16000Hz. When we first tried to listen to it all the sounds were the same. After much work we learned that we were making a mistake by redefining the variable t in the equation with the new frequencies. We weren't supposed to redefine t but just use the original equation and domain. Then we listened to the sounds at freq=4000Hz and freq=16000Hz. The sound at freq=4000Hz was a base-like low pitch sound. The sound at freq=16000Hz was a high-pitched sound with a shorter duration. These sounds are different because the frequencies are different. When the frequency is lower the sound gets stretched out. When the frequency is increased the sound is condensed. Our last manipulation of the sound was adding two sounds together.We added the sound of freq=4000Hz + the sound with the freq=16000Hz. The sound was louder and a mix of both sounds. This sound was a combination of two sounds unlike the previous ones which were just one sound signal.
March 13, 2007
Today we conducted a small project. We recorded 10 seconds of a WCBS news radio signal using WinRadio.Then with the use of MatLab we recorded the signal in MatLab and found out the sampling frequency which was 48000Hz. Then we plotted the signal in time. To plot this graph we experienced some difficulty in the beginning because the length of y and t were not the same. Thus we checked the length(y)=528384 and according to this t=0:1/48000:528383*1/48000. By doing this the length of t matches the length of y. The first two graphs illustrate what we have just done. The first graph is a plot of the whole 10 seconds of data we collected. The second graph is a plot of 0.1seconds. A fraction of the signal.
March 15, 2007
Today we focused on using GUI in MatLab. GUI stands for graphical user interface and is a easier program to use because it doesn't require you to memorize commands and syntax. First we began by learning how to locate the directory of GUI files. Then we executed the GUI in MatLab. Once the GUI was launched we loaded previously saved wave files and generated sound. The sampling frequency was displayed correctly but the ending time was slightly off. Instead of 2 seconds it was 1.7529 seconds. Then we listened to the file with different start and stop times and different sampling frequencies.
Then we continued by learning how to generate and plot the recorded signal in GUI. First we a generated a 1-component sinusoid witha sampling frequency= 200, start time=0, stop time=1 and comp=1 and f1=20. Then we plotted the signal. By changing f1 we found a change in the peak of the frequency graph. When f1=20 the peak was at 20 and when f1=40 the peak was at 40. When we generated a sinusoid with two components there were two peaks in the frequency graph.
To see what happens when we generate a noise signal with a noise level at 0.5 we found that there is no particular peak and you cannot tell what the frequency is. When we generated different noise signals with different noise levels we realized that the amplitude changes.
Then we studied different signals of already saved files. We found that these files had more than one frequency peak. We also had fun experimenting with the sound by modifying the frequencies. We also had a introduction into the hardware that was setup. Things like functional and signal generators. And also about carrier signals which change the frequencies so you can listen to more stations. There were also two boxes set up. One has a frequency up to 5Hz and the other one has up to 1kHz. The amplitude of the signal is where all the information is and the signal is continuously moving up and down. This is because 2 signals are superimposed.
March 20, 2007
Today was unfortunately our last class. Today we had to put together everything we learned throughout the whole session and simulate the wole radio signal process done by the Mariachi project. We know that an AM signal will be generated thus the range of frequency will be between 500Hz to 1500Hz. Our task was to recieve a radio signal using WinRadio, record it and determine the frequency of the signal. In AM demodulation mode, we recorded 10 seconds of signal with an IF bandwidth of 6.For our second attempt at recording the signal we chose an IF bandwidth of 8. And then we plotted this two graphs shown below. For AM signal 1 and AM signal 2 we found the frequency to be at 750Hz.
For the next set of graphs we changed the demodulation mode. For AM signal 3 we chose CW with an IF bandwidth of 2. In this signal we also found the frequency to be 750Hz. In AM signal 4 we chose DSB as our demodulation mode and an IF bandwidth of 6.5. This also resulted in the same frequency of 750Hz.
The IF bandwidth seems to the control the main area you want to record in a signal. As the number increases the area between the bars increases.
Then Jay verified our results by showing us how the hardware also gave us a frequency of 750Hz. He also showed us how changing the frequency on the box changes what you see in the WinRadio signal reciever. As the frequency increases it becomes more spaced out.
Synopsis
I learned quite alot about radio signal and radio signal processing. I feel I learned most about the MatLab program and how it is used and how it is useful in the mariachi project. I learned how you can manipulate MatLab and several different commands and syntax of the program. I also learned how the lab deals with additive noise in the signal and thru MatLab I learned how you can minimize noise. But in the laboratory it is very difficult to get a pure signal. I also got a chance to see the antenna used in gathering data which was very exciting. Most importantly I got a chance to work with different types of softwares and programs which I had never come in contact with before. I learned how to assemble the equipment and alot of techinical terms and information about radio signals and radio signal processing. Overall, I feel I learned alot about something I generally would have never considered exploring and this experience has been grat. Thanks Jay!
SESSION 3
March 22, 2007
Today we were introduced to cosmis rays and the tools use to measure some of the properties of cosmic rays. Cosmic rays are made up of gamma rays and neutrinos. These particles are very similiar to the particles found in our solar system. Cosmic rays have very high energy and the source is unknown. This is the basis of this project.
There are many reasons as to why cosmic rays are important and should be studied. The laboratory hypothesizes that learning more about cosmic rays can tell us more about the building blocks of matter. This can enable them to possibly learn about the origins of life and the future of the universe. They produce short-lived radioactive material and may help with evolution. Cosmic rays are highly concentrated as you go up and increase altitude. Outside of our atmosphere there are millions of cosmic rays but the earth's atmosphere shields the earth from most and thus not all cosmic rays travel to the earth. Cosmic rays collide with molecules and create showers of molecules. The very end of the showers is what reaches the earth. There are many ways to detect these particles. Charged particles can be detected directly. This is because when the cosmic ray hits a molecule it disturbs an electron of the atom and can tear off the electron. It is possible to detect disturbed electrons. Some apparatus' used include xrays, cloud chamber, spark chamber, scintillator counters.
In the lab we got a chance to see what a cloud chamber and spark chamber looks like. We also got a chance to see the different parts of the scintillator counter. Then we learned how to connect different wires into the scintallator counters and then into the channels, discrimnator and coincidence. Then we viewed this graphically using an oscillator and learned about the different properties of the graphically representations.
March 27, 2007
Today we did alot more hands on work with the scintillator counters. We first connected all the wires from the scintillator to the channels and then conducted a small experiment to examine the precision to which we could calculate the number of counts per sec of the coincidences and also of each of the channels. The first graph depicts our results of the number of coincidences in 20 second intervals. We collected data over a shorter time interval to see whether the number of counts per sec is more precise and accurate if data is taken over shorter time intervals or larger time intervals.
The graph below shows the number of coincidences per sec. This data was taken over 120 sec interval.
From doing this experiment we found that when you take the number of counts over a longer period of time the number of counts per sec are much closer than when you take the the data over a 20 sec interval. It's hard to determine the exact number because while doing the experiment we were bought to the realization that the person who stops the stop clock doesn't stop it at exactly 120 sec and the person who stops the counter doesn't exactly stop the counter at the same time as the timer. Thus there is a possibility of human error introduced into this data. Then we continued using the scintillator counters, this time we counted over a range of voltages.
The first graph shows the coincidence rate per sec and the voltage is changed.
This next graph if the rate of counts in the two separate channels. Series 2 is the first scintillator and Series 1 is the second scintillator. As the voltage decreases the count rate also decreases. We also noticed and learned that the second scintillator has slower count rate than the first scintillator. This is because not all the rays that hit the first scintillator hit the next one. There could be rays at different angles that could completely miss the second one.
March 29, 2007 Today we worked with a program called DAQ(data acquistion). This is a build in software that makes collecting data from the scintillators an easy task. At first we started with 20 second intervals but later decided to change it to 120 sec for more accurate and precise data. We also learned how to special things with excel that made data collecting and processing a whole lot easier. We collected data over aa series of different voltages starting for 5.0 to 6.0 V over a 120 second interval for each. We saw that as the voltage increases the efficiency also increases but as it approaches 6.0 V it seems to level out and mayb experience a drop if the voltage is further increased. This may be due to the fact that the equipment used can only be set to a maximum of 6.0 V and thus it may not be as efficient for voltages that are more than 6.0. The graph below depicts our results in a more cohesive manner.
Brainstorming for Our Project
As a group in class we got together some ideas about curiousities we had about cosmic rays. And we decided to further analyze what we could do with the questions we've asked and how. So we got together and came up with several ideas and decided to take some out all together.Most of these ideas are related to each other and we are hoping we can find a way to put all these questions into one big project.
After much discussion we came up with four questions we were interested in doing: 1. Do Cosmic Rays pass through all materials? -For this question we came up with several possible methods. One which we discussed in class was the building as a material. One scintillator on top of the building and the other in the basement. Besides this we thought we could actually count the number of cosmic rays that may be deflected or may not pass through to the second scintillator by placing a tank of water between them. We weren't so sure if this would work but we decided to put this idea and see what Dr. Marx thinks. Other things along these lines would be a mirror, cloth, and to compare results we would have a control.
2. Does it matter where you are? -This is sort of like the building between them and how you place the scintillators. All these questions seem to tie into each other and this one we could figure out by testing it in different places.
3. Does it matter where the counters are relative to each other? -We plan to work this problem out the same way as the previous one by experimenting with different positions and collecting data.
4. Do the number of Cosmic Rays depend on light and dark areas? -This question we came up with as a follow up to the previous class. As we were exploring their research we found that they were unsure of why their are more cosmic rays at night. We decided to pose this question to see whether light affects the amount of cosmic rays the scintillator can detect or maybe something greater about the universe that governs this phenomenon.
We were stumped on how to solve our question about measure the energy of cosmic rays. We discussed several things.We were wondering how in the lab do you know whether it is a high energy cosmic ray, meaning how do you differentiate between a low energy cosmic ray from a high energy cosmic ray? What kind of equipment does the laboratory use in their experiments? Also after detecting the high energy cosmic ray how do you study its properties in just that split sec? What kind of data is collected to study the high energy cosmic rays?
April 10, 2007
Today we began to work on our project and trying out the things we had thought about. We focused on our fourth question regarding light and dark areas. We were hoping to see if we could formulate an experiment by collecting this data and we found no significant change when we counted the cosmic rays in the light and then in the dark. The data below is what we collected on tuesday.
Thus on thrusday we decided to continue working on our other question pertaining to different materials.
Experiment Design
Objective We are testing to see whether or not cosmic rays pass through all materials.
Hypothesis Not all Cosmic Rays pass through all materials. There may be some that are unable to pass through different materials because a material can be more dense or less dense. We think more dense material will result in fewer cosmic rays passing through than less dense material. We also think that it might be possible that cosmics rays get reflected off of certain surfaces.
Materials Our basic equipment will be the scintillators which will enable us to count the number of cosmic rays and coincidences. Other things we will use will be the computers in the laboratory and a mobile scintillator.
Procedure On thrusday we want to begin by collecting data throughout the building. One on the roof top, tin roof, concrete,and in the basement. We plan on splitting up into teams so we can get this data collected in the time allotted. In the data we collect we will be testing the scintillator both standing upright and laying flat. This will allow us make a more precise conclusion of our data because we will have more statistics.
April 12, 2007
Today we decided to look into our question about cosmic rays passing through all materials. So we went up to level D in the physics building and collected data. We also collected data from level C. When we analyzed our data we saw that the overall rate decreased but we still need to collect more data to verify our guess. Below is the table of data we collected.
April 17, 2007
Today we were not able to work with Cosmic Chris due to technical difficulties. However we still continued our work on cosmic rays. We split into two groups and collected data to learn more about cosmic rays. Below is a table of data collected for different positions of scintillators around a hexagonal shape.
The graph below pictorially depict our results.
The number of counts increased as the postion got closer to the vertical postion. This way we learned that most of the cosmic rays are coming straight down rather than horizontally or even diagonally.
The second group conducted an experiment with increasing vertical distance. The table below summarizes their results.
As the vertical distance increased the rate of coincidences decreased. This tells us that the farther apart the scintillators are the less likely it is for the same cosmic ray to pass through both. This can also mean that not all cosmic rays go straight through the atmosphere. Many do not reach the earth's surface.
April 19th, 2007
We again split into two groups today. Virginia and I continued our experiment of cosmic rays passing through material. We again started at the D-level. This time a different location and continued to take data at the C-level, A-level and basement. We found it really hard to find a significant difference floor to floor so we decided to skip the B-level and take data at A-level and compare it with the data found at D-level.
We thought that as we went lower and lower the rate decreased and thus leading us to conclude that not all cosmic rays can pass through all material some may get blocked. However when we graphed our results we saw that the error bars overlap and thus we could not make a conclusion from these results.
April 24, 2007
It was bought to our attention that maybe there was an error when we were counting by thousands because our numbers were always off by a factor of 1000. So to see which number was correct we decided to take one trial on each floor to correct our data. And we found that our error was our counting was off by a thousand. Our corrected and final data is:
In the new graph the error bars do not overlap and we can conclude that cosmic rays do not pass through all materials. As we went down to the basement the count rate decreased showing us that some of the rays were absorbed by the material.
Reflection
This is the end of our Wise 187 session 3. It was a great hands-on learning experience. After working and learning about the mariachi project I can say that I know alot about cosmic rays. Never having heard about what cosmic rays were I was able to do design and conduct experiments to explore their properties. Doing these experiments has led us to ask ourselves more questions about their properties. I feel confident in the work I've done with my group members. It was helpful to learn about the features of Microsoft Excel and how to use them as well as the meaning of statistics to the data we collected. The only drawback was that we didn't have enough time to conduct our studies and collect more data. Overall, all of our project leaders were helpful and motivating. They gave us a chance to explore what was on our mind and guided us. They really put alot of effort into this and it made us feel great about our work.
Thank You!
Our final report can be found here: Wise Final Report
