EECE 380 Design Studio III

Memorandum #10

March 31, 2014

To: Dr. David Michelson

From: Danny Kim, team leader

This memorandum serves as an update for progress of the EECE 380 Design Studio III team, L2C4, during the week of March 24 – 31, 2014.

Hardware Updates:

For our power management system, we will be using three sets of solar panels in series that are capable of producing 20 V and 200mA. When we tested the solar panels on a sunny day, three panels together were outputting around 180mA and 19V even though they were not set up to be most efficiently.  When we hooked up the solar panels to our power management system circuit, the battery was charging according to our expectations.

With the battery alone, we were able to power the Q4000 on standby mode but we have not yet tested the battery when Q4000 would send a message to the satellite to see the current it draws.

This week we were successfully able to implement both our electrical temperature sensor and our wind turbine, which is our electromechanical sensor. We are still currently working on the implementation of the Arduino code for the accelerometer. We will send these three sensors, as well as the current voltage of the battery into the Q4000 through a multiplexer, since there are only two analog inputs. Voltages from each of these inputs will be read periodically by the microcontroller, and then an average value over approximately 10-15 cycles will be calculated and sent to the server via email. We expect to send updated data at least once per minute, if the microcontroller can handle this traffic. We have yet to test the integration of the sensors with the Q4000.

We were also successfully able to complete the flotation structure for the ocean buoy.

Software Updates:

The Embedded C code is able to interface six analog inputs through a multiplexer. The digital outputs from the Q4000 are used for the selector pins of the mux. We switch between mux pairings at each timer event. The email bodies contain all sensor data in specific JSON format to be parsed by the web server.

The web server now writes to a web page that is viewable on all devices on the same LAN. The URL was set up to be localhost:8888/view/surfingconditions, which can be accessed when the Python server is running. This web page displays the most recent surfing condition data, rather than long term data, since our target audience, surfers, would not need to know the surfing conditions from last week, or even two days ago.

February 23, 2014

To: Dr. David Michelson

From: Danny Kim, L2C4 Team Leader

This memorandum serves as an update for progress of the EECE 380 Design Studio III team, L2C4, during the week of February 17 – February 23, 2014.

We had our weekly team meeting on Monday, February 17, where we talked about our progress in the software and hardware portions of the project from the previous week.

Updates on Hardware Portion:

The 4 pole crystal ladder filter we previously designed did not have enough gain from its resolution  peak from the noise of the circuit as we hoped. We decided to improve our design by building a 2 pole crystal ladder filter with a better gain. With our original filter having ~1 KHz bandwidth, our new filter has a bandwidth of ~2 KHz in order for us to see how high the peak of a signal is. Previously, the signal was getting attenuated but as a result of our improved crystal ladder filter, at our centre frequency, we are getting a gain of ~10 dBm when the Mixer, Voltage Controlled Oscillator, and RF Amplifier are all connected.

We were having trouble with the output of the crystal ladder filter being too low of a voltage to be accurately measured by the peak detector. We decided to add an amplifier after the filter and before the detector. We designed two different solutions. The first is a CE-CB cascode amplifier that creates isolation from the input to the output and the second is a 4th order butterworth low pass filter using 2 high speed amplifiers. The butterworth was able to pass a signal through with much less distortion and we were able to create a voltage gain of up to 100V/V. We are unsure of which one to use as of now. The butterworth is a much better amplifier, but it comes with the cost of a much more complex circuit.

We spent this week solely on hardware, so there is no update from software portion this week.

In the following week, we plan on meeting on February 24th to discuss current state of the project and plan our goals.