Systems and Communications Commons^™

Constant Conduction Angle Biasing For Class C Monolithic Rf Power Amplifiers, Gursewak Singh Rai

Master's Theses

In modern wireless communication systems, a base station typically serves a few hundred users within its cell coverage. To combat the near-far problem – the situation where a nearby user’s strong cellular signal masks the cellular signal of a faraway user – base stations continually enforce power control. That is, nearby users must lower their transmit power. In CDMA technology, power control can be as large as 70-80dB. At low power outputs, this greatly impacts the performance of the RF power amplifier (PA) in the cellular device. For small RF drives, the magnitude of the output RF current approaches the …

3.5 To 30 Mhz Automatic Antenna Impedance Matching System, William Blodgett

Electrical Engineering

Two-way communications using 3 to 30 MHz, high-frequency (HF) radio, also known as shortwave radio, provides worldwide coverage with no infrastructure required between stations. Amateur or “Ham” radio operators apply this advantage to long distance communications and to provide disaster relief communications. Optimum frequencies for long distance propagation are time-of-day variant necessitating an operating frequency range of 3 to 30 MHz. HF half wave dipole antenna length varies from 15 to 150 ft over this range. Fixed-length antenna impedance varies with frequency due to physical dimension dependent capacitance and inductance. Maximum transmitter to antenna power transfer occurs when the transmission …

802.15.4 Low Intermediate Frequency Radio Receiver, Sanjay Avasarala

Electrical Engineering

This project involves the design, building, and testing of a low intermediate frequency 802.15.4 receiver that uses an FPGA to perform final demodulation to baseband.

Pulsed Class-G Rf Amplifier System, Kevin Maulhardt, Kevin Haskett

Electrical Engineering

No abstract provided.

Rfid Check-In System For Safe Routes To School At Hawthorne Elementary, Paul Banel

Electrical Engineering

The system uses a low frequency Radio Frequency Identification (RFID) reader and passive RFID tags to help the Safe Routes to School program at Hawthorne Elementary in San Luis Obispo track the number of children who participate in the program. Children will carry passive RFID tags and scan them at the reader each morning that they walk or bike to school. The system tracks the total number of students that walk and bike each day, as well as the number of times each individual child participates over the course of many days. The Safe Routes program hopes to use this …

Lyfi, Kianoosh Salami, Justin Cotton, Elush Shirazpour

Electrical Engineering

This paper will cover the steps necessary to design, build, and manage networkable smart light switches over WiFi via a mobile application. It contains a microcontroller running a real time operating system, a WiFi module, a Java server with SQLite databasing, and a mobile phone application.

LyFi is designed to turn on/off and dim household lights while only requiring the same installation procedure as a less capable dimmer switch. Once installed and connected to a network, LyFi will self-discover and configure. The server automatically propogates a database of nodes where any mobile device running an application can receive an updated …

Linear Power-Efficient Rf Amplifier With Partial Positive Feedback, Matthew E. King

Master's Theses

Over the last decade, the number of mobile wireless devices on the market has increased substantially. New “multi-carrier” modulation schemes, such as OFDM, WCDMA, and WiMAX, have been developed to accommodate the increasing number of wireless subscribers and the demand for faster data rates within the limited commercial frequency spectrum. These complex modulation schemes create signals with high peak-to-average power ratios (PAPR), exhibiting rapid changes in the signal magnitude. To accommodate these high-PAPR signals, RF power amplifiers in mobile devices must operate under backed-off gain conditions, resulting in poor power efficiency. Various efficiency-enhancement solutions have been realized for backed-off devices …

Spectral Shape Division Multiplexing (Ssdm): Apparatus, Transmitter, Receiver And Detection, Fausto Daniel Holguín-Sánchez

Master's Theses

Wireless communication companies require to use the frequency spectrum to operate. Both frequency licenses and infrastructure to reuse frequencies are costly resources subject to increasing demand. This work introduces a novel multiplexing method that saves spectrum called Spectral Shape Division Multiplexing (SSDM). Under certain configurations, SSDM displays higher flexibility and throughput than other spectrally efficient methods.

SSDM defines the structure of a wireless multi-carrier by software. It is similar to Orthogonal Frequency Division Multiplexing (OFDM) in that both use overlapped sub-carriers to make efficient use of allocated spectrum. However, SSDM has several advantages. Where OFDM organizes sub-carriers orthogonally, SSDM allows …

Auto-Tuning Antenna, John Chen, Jennifer Tighe

Electrical Engineering

Radio transmitters and antennas have differing impedances at the output and feedpoint, depending on frequency. Modern antenna tuning methods involve manual or automatic resistance and reactance network adjustment to match transmitter and antenna impedance. This reduces power reflections to the transmitter, but introduces losses and prevents full transmitter power from being radiated at the antenna. This project utilizes a variable length antenna element to tune and match transmitter and antenna impedances, allowing efficient power transfer to the antenna. The antenna length varies from 0 to 30.5 inches. The method involves an RF signal with a maximum power of 2 watts …

Wireless Passive Power Transfer Using Wire Antennas, Sheng Da Zhang

Electrical Engineering

This project tests and analyzes the efficiency of directional and omnidirectional antennas in wireless power transfer for charging. The project demonstrates the steps of construction and properties of dipole, monopole, and Yagi Uda antennas. A low power high frequency DC rectifier circuit converts the received RF power from the antenna and stored it as DC voltage on a capacitor. The receiver circuit also estimates the power received by the antenna. Wireless RF power transmission proves to be inefficient for short distances. The best efficiencies of the antennas were under 50% even at 0.1meter. The near field attenuation starts at around …

San Luis Obispo Transit Tracker System Back-End Server, Daryl Alan A. Dimalanta

Computer Engineering

This document gives the rationale, design process, technical implementation, testing procedures, and testing results of a back-end server used for the San Luis Obispo (SLO) Transit Tracker System. The SLO Transit Tracker System (SLOTTS) includes client software installed on mobile devices and a back-end server. The purpose of this system is to encourage SLO residents to utilize the transit system by having the client software present current bus location, navigation instructions, and bus schedule in a simple, fast, and easy to use mobile application.

Due to the limited central processing unit (CPU) and limited power supplied by the battery, route …

An Investigation Into Ultrasonic Communication For Near-Body Networks, Eric Joshua Escudero Jr., Gursewak Singh Rai

Electrical Engineering

The following report presents a study of body-area, free-space ultrasonic communication system. Two analog communication systems are investigated. The initial communications system setup relies upon the amplitude modulation (AM) techniques to transmit the signal. Such a system is prone to noise since the amplitude of the signal is directly affected by distance and the signal strength will deteriorate. The secondary communication system involves utilizing frequency modulation (FM). This method avoids the issue of losing information due to amplitude deterioration, but encounters delay issues. The main hardware components used in the approach outlined include ultrasonic transducers (UTs) used for both transmitting …

Digital Modulations Using The Universal Software Radio Peripheral, Daniel Keith Artis

Electrical Engineering

Software defined radios (SDRs) are versatile systems that integrate hardware and software to create a reprogrammable wireless system.  Due to the versatility and hardware requirements of a SDR, they are typically expensive and not always affordable for educational institutions.  GNU Radio is a free software package that allows users to do signal processing on any computer using python and C++.  Using the Universal Software Radio Peripheral (USRP) board in conjunction with a standard personal computer (PC), a RF daughterboard, and the GNU Radio software, we can create a software defined radio that can transmit, receive, and process signals.  Because the …

Wirelessly Operated Pa Loudspeaker System For Rmax Search-And-Rescue Uav: A Preliminary Design, Travis Luke, Nolan Uchizono

Electrical Engineering

This paper discusses the approach used to implement a wireless PA loudspeaker system on a search-and-rescue RMAX UAV.

The purpose of this project is to allow the continuation of communication between search-and-rescue workers as well as potential rescuees in an environment that won't always allow it. Since rugged terrain tends to cause interference between two radio communications, there needs to be a way to bypass this problem. In addition, people in need of rescue are unlikely to be using a radio on an emergency frequency, so there needs to be a way to efficiently issue orders or evacuation notices without …

Laser Cursor, Michael Liman

Electrical Engineering

A user controls a cursor on a computer screen using a laser pointer.  A camera picks up the laser pointer’s position and sends the data to the computer to move the cursor in the correct position.

Discrete Alarm Clock, Travis Moore, Collin Barth

Electrical Engineering

The standard alarm clock, as used daily by millions worldwide, has clear room for modification and improvement.  This paper documents an implementation that rectifies many of these flaws.  Improvements include adjustable snooze length, an IR remote for ease of use, and an RF headset for discrete alarm use or potential incorporation into a device much like a hearing aid.  The processes involved in creating a digital alarm clock, as well as the obstacles met in the implementation of the enhanced design, are detailed within.

Wireless Sensor Network For Energy And Environmental Monitoring: Helping Old Buildings Go Green, Jacob Power

Electrical Engineering

Today, the rising cost of energy and social trend of “going green” has put increasing pressure on commercial property owners to improve the efficiency of their investments.  There is good reason for this, too.  In the State of California, office buildings represent the single largest user of energy in the commercial sector.  This project consisted of the design, implementation, construction, testing, and deployment of a wireless sensor network for energy and environmental monitoring in retrofit commercial office installations.  The analyzed data generated by this system can be used by building management and owners to identify areas of inefficiency within the …

A Neural Network Receiver For Em-Mwd Communication, Timothy P. Whitacre

Master's Theses

Baseband digital communication in electro-magnetic measurement while drilling (EM-MWD) systems is often corrupted by non-white surface noise. The inability to reliably decode the transmitted signals in a noisy environment limits the depth at which EM-MWD systems can operate. Correlation receivers, which are optimal in the presence of additive white Gaussian noise, can be sub-optimal in the presence of various types of field noise at different drilling sites.

This thesis investigates the application of artificial neural networks (ANN) as communication receivers in EM-MWD baseband digital communication systems. The performances of various ANN architectures and training algorithms are studied and compared with …

Aether, Thomas Cameron, Kristine Colton, Daren Childers

Electrical Engineering

Aether is a RC-style autonomous air vehicle that utilizes GPS positioning along with a wireless communication system to achieve a computer-controlled flight.

This report will incorporate the acquisition, design, integration, implementation and testing phases of the UAV development. Furthermore a discussion of troubleshooting as well as improvements for future projects will be included.

Audio-To-Optical Conversion And Transmission, Jason Moritz

Electrical Engineering

The purpose of this project is to understand free-space optical transmission of signals in the application of transmitting an audio signal. An audio signal will be taken from the headphone output of a computer and used to modulate a current source driving an LED and a laser diode. The optical signal will then be transmitted through free space as well as two different focal length lenses and converted back to an audio signal to measure any attenuation or gain in the original signal. My experimental results showed that the LED was able to transmit up to 10 dB more power …

Directional Patch Antenna Array Design For Desktop Wireless Internet, Noah Snyder

Electrical Engineering

To improve desktop wireless internet access, two patch antenna configurations were investigated in order to find an alternative for a dipole antenna, which is commonly used for Wi-Fi access. A Linksys WMP54G pci-card wireless adapter was used to test three antennas for 802.11g communications. The standard WMP54G dipole antenna and two patch antenna configurations were tested for Wi-Fi signal strength. The antennas were also tested in Cal Poly’s anechoic chamber to obtain resonant frequency and gain measurements. A 2.437 GHz center frequency, 72 MHz bandwidth antenna consisting of a single microstrip patch was constructed. After the patch antenna was determined …

La Traducción Del Software De Mindbody Al Español, Molly Kathryn Mcfarland

World Languages and Cultures

This project entails the translation of the business management software of MINDBODY to Spanish to facilitate international communication and commerce for the company. This translation is meant to better equip MINDBODY with the tools necessary to engage in bilingual international commerce. Translation of this software demo is intended to aid the company’s Spanish speaking clientele and prospective clients by breaking down many of the language barriers they currently face with the software in English, and also to promote the recognition of the growing need for bilingualism in the rapidly changing world, both within and outside the realm of business.

The …

Characterization Of The Rfx400 For Use In Software Defined Radio, Edward Adams

Computer Engineering

While software defined radio is an extremely flexible technology that is fairly rarely used, as a single purpose radio is much cheaper, it provides an excellent means of learning RF and communications skills through the lens of digital electronics, and it would behoove a Cal Poly student interested in these areas to take on a project in software defined radio. This project aims to lower the barrier to entry for future students to undertake such a project. The use of an up-converter/down-converter is documented for future students to interface with.

Ofdm Simulation In Matlab, Paul Guanming Lin

Electrical Engineering

The objective of this project is to demonstrate the concept and feasibility of an OFDM system, and investigate how its performance is changed by varying some of its major parameters. This objective is met by developing a MATLAB program to simulate a basic OFDM system. From the process of this development, the mechanism of an OFDM system can be studied; and with a completed MATLAB program, the characteristics of an OFDM system can be explored.

Micro Forest Fire Detection, John Cape

Electrical Engineering

No abstract provided.

Circular Polarized Splatch Antenna, Cynthia Truong

Electrical Engineering

The Splatch Antenna combines excellent performance and cost-effectiveness into an antenna package that can be integrated. The goal of this project is to figure out how to connect two Splatch antennas to realize a Circular Polarized (CP) antenna. The advantage of CP versus linear polarization is that CP eliminates polarization mismatch losses caused by Faraday’s rotation.

Sign Language Glove, Nicholas Born

Electrical Engineering

Between 500,000 and 2 million Americans use American Sign Language (ASL) as their primary language. As such, a device capable of translating those movements into text would be useful in many areas, such as teaching and the entertainment industry.

The goal of this project was to show that the creation of a glove device that takes in sign language letters, interprets them into the desired characters, and can input those characters into a computer is feasible. I chose to work on this project for many different reasons. One reason is many members of my family know sign language and use …

Aperture Coupled Microstrip Antenna Design And Analysis, Michael Paul Civerolo

Master's Theses

A linearly-polarized aperture coupled patch antenna design is characterized and optimized using HFSS antenna simulation software. This thesis focuses on the aperture coupled patch antenna due to the lack of fabrication and tuning documentation for the design of this antenna and its usefulness in arrays and orthogonally polarized communications. The goal of this thesis is to explore dimension effects on aperture coupled antenna performance, to develop a design and tuning procedure, and to describe performance effects through electromagnetic principles.

Antenna parameters examined in this study include the dimensions and locations of the substrates, feed line, ground plane coupling slot, and …

Fm Radio Receiver With Digital Demodulation, Nicholas Burnett

Electrical Engineering

This paper reports on the design, construction, and testing of an FM receiver. The design is split into two portions, the analog FM front end and the digital demodulator. The job of the front end is to down convert the RF signal to a frequency that is low enough to sample with an analog to digital converter. The construction of the front end is done using what is known as “Ugly Construction.” That is, all the components are soldered together floating over a ground plane.

The second portion of the design is the demodulator. The phase lock loop method of …

Touch Screen Sound Controller, James Fenley, Jonathan Law

Electrical Engineering

The Touch Screen Sound Controller sets out to explore the use of a touch screen as a sound control interface for the disk jockey profession. In addition, the project aims to provide an alternate means of transferring audio data by way of TCP/IP communications as opposed to MIDI. By applying our method, a user may stream pulse-code modulated data from a server onto a client’s RAM via an Ethernet connection. A 32bit, 200MHz ARM9 microprocessor addresses data from the RAM and proceeds with executing DSP instructions from the user. The connection between the touch screen and the central microprocessor is …