Senior Design Project

In order to graduate from the Engineering program at San Diego State University, each student needs to complete a senior design project with a team of between 6 to 10 students. The group that I’m apart of is working on building a system to localize nodes in a wireless sensor network (WSN). We do this by using signal strength and, when nodes are in line of sight of each other, ultrasonic transducers to measure the time difference of the received ultrasonic signal and the radio signal. This is a problem that has been tackled many times and I’m pretty sure we won’t be able to come up with anything novel in the short time we have, but the task of building the working system is what is important.

Partially populated node rototype board

Partially populated prototype board

I’m in charge of building the GUI and integrating the software side of the system. For the GUI I’m using Qt. I’ve used this before and found it pleasant enough although I still run into issues that cause me to waste more time than I’d like. The most important thing for me was that Qt is cross-platform and has great documentation. Having some high-profile applications such as Google Earth and Skype using it makes it easier to “sell” to the other team members as well.

For the WSN we chose Atmel Zigbit modules. These have a ZigBee wireless chip and an ATMEGA128 microcontroller embedded within. This module was chosen because much of the difficult circuitry was taken care of, previous good experiences with AVRs, and the low-cost of the hardware and development tools. Thus far we’ve created custom PCB’s to hold the Zigbit modules, a pair of ultrasonic transducers, and the accompanying circuitry. We are currently testing those so that we can get about 20 boards professionally made.

We’ve got less than a month to finish up and are working feverishly to get everything brought together and integrated. With luck we’ll have a working system in a couple of weeks.

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