Uncategorized – SYMON MUTHEMBA

Recognizing “ndiyo” and “hapana” speech using MATLAB algorithms and FFT functions

symonmk — Tue, 18 Jul 2017 14:24:00 +0000

Ndiyo means yes in Swahili and hapana means no. The two words were chosen as they can be used to make very simple applications that may require a yes/no response such as an automatic telephone prompt system. Swahili translations of yes/no applies to the national language of Kenya, and an interface that recognizes the words can be used in local applications. Simple speech recognition The first step is to obtain speech samples of ndiyo and hapana from a large sample of people throughout the country. This can be done using a simple microphone and a recording instrument. For this project however, I took the generic pronunciations of the words from Google translate: ndiyo, hapana (I know, sounds weird). We can now plot the two audio files as a periodogram Power Spectral Density plot using fast Fourier transform (FFT) in MATLAB. FFT is simply an algorithm that makes computation of discrete Fourier transforms (DFT) more efficient by reducing the amount of computations involved. OR This gives the plots in figures 1 and 2. According to the two plots above, we can see that the signal for ndiyo has more energy in the lower frequencies than that of hapana. We can use this feature to differentiate the two signals. When the signals approach 4kHz however, they exhibit features that are similar and harder to differentiate. Trial and error resulted in a range of 0 to 3620 Hz for the lower frequencies and 3620 to 11025 for the higher frequencies. A threshold value is necessary for the separation of the features, this value is obtained by calculating the feature for all of the audio samples and examining the histogram for the ndiyo and hapana values. I chose a threshold value of 12 as an example but in practice this figure should be computed. The speech recognition algorithm is: Using this algorithm, the output for the speech recognition function on the two audio files is: This shows that the algorithm exercise was successful in distinguishing the speech from two audio sources using a simple recognition algorithm. REFERENCES AND SUPPORTING ARTICLES ‘Power Spectral Density Estimates Using FFT’ https://www.mathworks.com/help/signal/ug/power-spectral-density-estimates-using-fft.html. ‘DSP Mini-Project: An Automatic Speaker Recognition System’ http://minhdo.ece.illinois.edu/teaching/speaker_recognition/speaker_recognition.html. ‘Basic feature extraction and classification of audio files’ https://ccrma.stanford.edu/workshops/mir2011/Lab_1_2011.pdf. Enhance your DSP Course with These Interesting Projects http://www.asee.org/file_server/papers/attachment/file/0002/2611/Enhance_your_DSP_Course_with_these_Interesting_Projects.pdf.

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Final Year School Project: Introduction to the Project

symonmk — Wed, 05 Apr 2017 16:07:48 +0000

For my 5th and final year in EEE at JKUAT, I was required to do a school project that accounted for two class units spread out over the two semesters of 2016/2017. The project I came up with is called OFFGRID MOBILE COMMUNICATION which the name suggests that communication can happen without a service provider network. Brief Abstract As communication is becoming widespread in Kenya, many people are opting for high-end smartphones that can do more than simple communication and support a variety of features. However, communication obstacles may arise due to several factors such as network congestion, deadzones within urban centers and extreme weather conditions. Let’s also not forget the dips in cell reception when we go to the rural countryside to visit our grandfolks on Christmas. A way to mitigate this constraint in communication is completely abandoning the dependency to the service providers and creating a small network based on two available technologies Bluetooth 4.0 modules and RF Transceiver modules. Together these are enough to create a small area network (radius 1 – 1.8km). Objectives My objectives for this project include: Design and implement the internal circuitry of the device including the Bluetooth, microcontroller and RF transceiver modules which will allow the device to transmit, process and receive data. Design and implement the code to configure the Bluetooth, microcontroller and RF transceiver modules to perform as intended. Design and implement an android application user interface to allow users to connect and work with the off-grid communication device as intended. Resources My project will involve the use of an ATmega1284P microcontroller, a HM-10 Serial Bluetooth 4.0 module and a HC-12 RF Transceiver module. I am using Atmel Studio to program my microcontroller (Newbiehack.com has great tutorials on this), KiCad, discussed here, to draw my schematics and eventually my PCB and Android Studio to write the mobile interface to use with the device. As of now in my final semester already made strides with this project more posts on its progress will follow. References Some references I used in researching for this project including the communication industry in Kenya, other solutions, wireless technologies (Bluetooth, RF), antennas, microcontrollers, mobile app development can be found below: [1] CA, “Quarterly Sector Statistics Report Fourth Quarter for The Financial Year 2015-2016 (April-June 2016)”, page 5. [2] CA, “Quarterly Sector Statistics Report Fourth Quarter for The Financial Year 2015-2016 (April-June 2016)”, page 9. [3] CA, “Quality of Service,”. [4] CA, “Mobile operators Fail to Meet Quality of Service targets for the third year running,”. [5] Abdiwahid Biriq. (2014, May. 16). “Is Safaricom short-changing its customers?”. [6] Dave Aiello. (2004, Aug 13). “Mobile Carriers Ready “Cells on Wheels” in Case of Outages or Network Overloads.”. [7] Chris Woodford. (2016, March 9). “Walkie-talkies.”. [8] AARL. “What is Ham Radio?”. [9] Chris Woodford. (2016, June 13). “How Does Bluetooth Work”. [10] ATHLOS. “Bluetooth™”. [11] Robin Heydon. “Bluetooth Low Energy: The Developer’s Handbook”. Prentice Hall, 2012, pp 1-7 [12] Tarun Agarwal “Block Diagram and Explanation of RF Transceivers.”. 33 [13] antenna-theory.com. (2011) “The Monopole Antenna”. [14] Louis E. Frenzel. (2005, Mar 31). “Printed-Circuit-Board Antennas”. [15] Freescale Semiconductor, Inc. “Compact Integrated Antennas”. Freescale Semiconductor, Inc, 2015 pp 8-9 [16] CA. “Kenya Table of Frequency Allocations”. CA, 2008 pp 37-186 [17] Frank Duignan. “An Overview of Microcontrollers.”. [18] Android Developers. “Bluetooth Low Energy”.

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Hello… Anyone here?

symonmk — Mon, 13 Mar 2017 19:38:28 +0000

If you’re reading this message that means you’ve stumbled upon my first post. At the writing of this post, I’m called Symon Muthemba and I’m a student pursuing a Bachelor’s Degree in Electrical and Electronic Engineering at the arguably prestigious Jomo Kenyatta University of Agriculture and Technology in Kenya. I’m 23 years old and in my final year of school. Now that that’s out of the way, I need to address the reason for the existence of this website. Despite my well-functioning memory, I realized that a lot of what I learn is eventually forgotten and not fully understood and appreciated. This website will serve as my personal collection of notes from the research and projects I will be participating (have participated) in that are in line with my interests. It will also serve as a conduit in which I share my thoughts and ideas on certain topics with the open world. My current interests are in the fields of signals and RF (radio frequency) engineering, circuit design, low level programming and electrical engineering in general. I will post on a regular basis as I learn the ropes to become a professional engineer. Let’s get technical!

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