Weekly Reports

Week 2: Sept 9-12

This week, the two of us met to discuss our first and second choices for the class project. We did some initial research in terms of pricing, components, feasibility, and optical design for each of the project choices. Based on this research we have decided our first choice will be the Traffic Observer. For this project we have investigated possible optical sources, as well as ideal microcontrollers available for data logging. Premilimary designs and cost allocations have been made according to parts found on websites such as digikey.ca and globalspec.com. We are continuing to research the feasibility of the remaining two topics to decide which one will be our second choice.

Week 3: Sept 13-20

As the topic selection was this week, Leigh and I extensively researched our first and second choices, which were the Traffic Monitoring System (TMS) and the Free Space Optics System, respectively. Our design proposal was written and a detailed initial design with initial budget approximations were completed as well. For the upcoming week, as we will be putting in our first order for initial components, we have already researched and obtained part numbers and prices for microcontrollers, lenses, LEDs, and other key parts for our design. We have learned today that our first choice was accepted, and will now begin further work on the TMS design - starting with the 555 timer modulator circuit.

Week 4: Sept 21-27

This week Michael and I further researched components and their prices for our design. We were introduced to our third “group member”, Roy, who is a graduate student with Dr. Fang and obtained his undergraduate degree in electrical engineering. We discussed our design with him and he gave us some feedback, especially with regards to the selection of the microcontroller. He explained to us how microcontollers work, and also how he has selected microcontrollers in the past. In the end we took his advice and decided to select a microcontroller that is well supported, meaning that many people use it. We have decided to hold off on purchasing a lens until we have tested our initial design (infrared LEDs) using spare lenses in the lab. In the event that our original design does not work, we will save money having not purchased the lens. If it does work we will purchase a lens immidiately. On Monday September 29, we submitted our order request to Ana. The parts we have decided to purchase from Digiky are: a 555 timer (LM555CNNS-ND), 2 infrared LEDs (1N6264), an infrared receiver (TSOP852) and a microcontroller (PIC32MX3XX). In the next week we will be working on our final design, including the 555 timer circuit, improved logic for detection and system mounting. We will also begin research on programming microcontrollers.

Week 5: Sept 28 - Oct 4

We have finalized our design this week as we presented on Friday, October 3. The electronics portion of the design has been finalized and proof of principle testing has begun as a Multisim simulation file was created for it. A powerpoint presentation and semi-final report was written and submitted on Friday describing our final design specifications for both the electronic and optical portions. We have decided on using three optical source/detector pairs and have begun to write our algorithm for determing the type of traffic that is encountered. Most importantly, the microcontroller was selected to be the PIC18F877 as it came with much online support and access to some key freeware programs including a compiler. We are going to attempt to use Infrared LEDs as our source and have received good feedback from Glen that we could be successful with our choice. If not, a contingency plan to use visible lasers with phototransistor receivers has been developed. There was much progress this week, and we await the arrival of our ordered components so that we may begin to build and take initial observations of our system.

Week 6: Oct 5-11

Our parts arrived this week. All of our parts were correct. We discovered that our receiver will not accept continuous signals at 38kHz as we originally thought. The signal sent out must be sent in bursts. The maximum burst to rest time is 70 cycles on to 10 cycles off. Also, the receiver must have leads soddered onto it. This means that we must create a second 555 timer in addition to the first in order to pulse the modulated signal. We are going to research this option. The downside to this is that it reduces our time resolution, since there will be 10 cycle bursts where the system will not be operating. Early calculations show us that this will not create an unreasonable amount of error, however we must investigate this more. As of now, no alternate receiver that accepts continous signals has been found. We discovered that visible lenses made of BK7 material will work in collimating our 940nm light source. Research on the microcontroller and how to program it is ongoing. Next week we will begin our proof of principle tests for the optical components. We will begin by testing the unmodulated IR LED using an IR photodetector indoors in order to determine how far it will go. Next we will test using lenses in the lab to see if they will work in collimating the IR light and what difference that will make in detection distance. Depending on what we decide to do with the receiver problem,we may begin working on the double 555 timer cicuit as well.

Week 7: Oct 12-18

This week we began testing our optical components. Both our infrared LED and our receiver work, and the two components work together. In order for the signal to be picked up by the receiver the LED must be modulated at 38kHz and in bursts of 70 cycles on, 10 cycles off. We did this using electrical equipment in the lab and received a good signal at the receiver. Due to the very small emission angle of the LED (~8 degrees), we are having trouble with alignment. We found that we need to start with the receiver and the LED very close together and then slowly move them apart in order to accurately align them. So far, we have managed to detect the signal from 7ft away, however the only reason that we could not go further is because the electrical components attached to the optical components were plugged into the wall. This week we hope to get into the lab and rearrange the equipment in a way that will allow us to test it at a further distance. It is not feasible for us to test the optical components outdoors at this point in time, however we plan to shine ambient light from a lamp directly through the path of the IR LED in order to mimick sunlight and determine how far the system will work outside. This far we have not needed a lens as previously suggested, because the LED beam is so narrow, and the receiver's detection angle is so large.

Week 8: Oct 20-24

The optical proof of principle test was a success. We were able to transmit a 38kHz, modulated signal to our infrared receiver across the lab diagonal, with ambient lighting and daylight. There was a slight problem however; after being blocked for a long period of time, the signal would disappear, only to reappear again after the beam was blocked a subsequent time. To fix this, we are going to experiment with the rest time of the modulated frequency, to see if perhaps it is too small, and the receiver is being overwhelmed. Another possibility could be that our receiver is defective and we must try another. However, the main importance, is that the signal was transmitted and received very strongly over a distance of approximately 35 feet. Also, for the upcoming week, we will have our electronics P.O.P test, which will include an understanding of the microcontroller capabilities as well as the completion of the 555 timer modulation circuit.