Memorandum 

Date:               March 23, 2014

To:                  Professor David G. Michelson

From:              EECE 380’s L2D4 Group

Subject:          Update on Orbcomm Design Project

This week we were working on the sensors and the Orbcomm programming. The hardware group had most of the sensors working well and the software group kept learning about the Orbcomm system following the lab tutorials. The goals of this week were building the sensors and familiarizing the Orbcomm system.

Software

This week we kept learning about the Orbcomm system. We worked on the flash file system and bash scripting. From the lab sections, we learned that the DemoAppFFS gets GPS location and stores that position in FFS. We modified the code in DemoAppFFS with Orbcomm specific commands to save inputs and send emails. Moreover, we created an email filter in our Gmail account, created a ‘.forward+orb file’ in the home directory and aggregated mail using Bourne shell. The goals of this week were achieved and we will keep working on the Orbcomm system next week.

Hardware

This week we purchased sensors, solar panels and some other electronic components. We had most of the sensors working properly. Specifically, the air temperature sensor, the water temperature sensor, the rain sensor, the pressure sensor, and the solar panels function well. Moreover, we built two timer circuits with variable resistors that control the frequency of a pulsing led. This way, we could have the buoy flash the led depending on the depth and distance from the coast they are. The tasks of this week were completed and we will be work on the wind sensor next week.

The goals of this week were achieved. The goals for next week will be working on the wind sensor, the multiplexer and Orbcomm system.

Memorandum 

Date:               February 16^th, 2014

To:                  Professor David G. Michelson

From:              EECE 380’s L2D4 Group

Subject:          Weekly Memo for Week 4

This week the software group completed the design of the display and the video filter by using myDAQ; the display has been tested and functions well, however, the video filter still needs additional testing. The hardware group completed the cascaded Common Emitter amplifier and a precision peak detector.

Hardware Sub-group

The goals of the team for the week were

• Build an amplifier which will be put after the mixer and before the peak detector
• Build and test a precision peak detector

Cascaded Common Emitter Amplifier

As the previous memo mentioned, an amplifier is needed to make the signal large enough for the peak detector. In this week, we have built a second set of cascaded Common Emitter amplifier in an attempt to have a performant gain. However, it did not function as what we expected. Then we investigated that the DC offset of the cascaded Common Emitter amplifier could give us a high enough output, related to the amplitude of the signal. Therefore, the amplifier will work well if we find the relationship between its output and the amplitude of the input signal.

Precision Peak Detector

This week we built a precision peak detector by using the high frequency op amps we received in order to enhance the accuracy. However, it does not function well at around 10MHz. Next week, we will make adjustments on the precision peak detector to solve this problem.

Video Filter

This week we built a simple RC circuit which is a low pass filter. After testing, we observed that it does not function accurately as a video filter when the signal is small. To meet our requirements, we decide to complete the video filter by using myDAQ.

The goals of hardware sub-group for this week are all achieved. Additional testing on the precision peak detector will be done. In addition, we are going to combine all parts of the project and perform testing in the next week.

Software Sub-group

The goals of the team for the week were

• Complete the display for the spectrum analyzer and perform testing.
• Complete the video filter

Display

In this week, we complete the display for the spectrum analyzer. Our display was having a problem of resetting in last week. To solve this problem we create a design block to set a range for the display and connect it to the reset port of the design block build XY graph. After testing we find out that this method solve the problem efficiently. In addition, we observed that the lowest readable signal of myDAQ is around 0.1V.

Video Filter

The video filter is completed by using a design block Butterworth filter and setting it to be a low pass filter. The high cut-off frequency we choose is 1.1MHZ. Testing of the video filter will be performed in the next week.

Logarithmic Amplifier

In this week, we have figured out how to build logarithmic amplifier by using the LabView. However, to complete this part, data collection and calculations of the relationship between DC voltage and power in dBm is needed. This task will be done in the next week.

The goals of software sub-group for this week are all achieved. We will complete the logarithmic amplifier, perform testing, and combine all parts of the project in the next week.