Monthly Archives: February 2014

Memorandum

EECE 380 Group L2B1

To: David Michelson, Associate Professor, UBC

From: Yuan Liu, Student

Date: February 23^rd, 2014

Subject: Weekly Review

Dear Dr. Michelson,

In this week, we finished most of the parts individually. For the hardware part, our group members managed to make the precision peak detector. With the 10 MHz op amps, our precision peak detector is now able to eliminate the 1 dB power inaccuracy during measurement. Besides, we built the video filter by a simple RC circuit, but during testing and troubleshooting, the circuit could not decrease the noise to a desired level. This problem was probably caused by the miscalculated resistor and capacitor values. After discussion, our group members decided to try another way to create the low-pass filter next week.

For the software part, we have made a progress in building the ramp and display. Using the Convert from Dynamic Data block, we could transform the sawtooth wave into a discrete one-dimensional array. Next, after implementing several math algorithms, we bundled the x and y inputs together and fed the signal into a display on the front panel. However, the algorithms still need to be calibrated to make sure that an appropriate x range can be displayed. In addition, our group members found a log algorithm available in LabVIEW, which was helpful to develop the logarithmic amplifier.

Next week, our goal is to assemble all the parts together and start testing and troubleshooting the spectrum analyzer project as a whole. Our hardware group needs to make a decent video filter to decrease the noise level on the display. For the software part, we should focus on testing and analyzing, and further adjust our algorithms.

With Regards,

Yuan Liu

MEMO

EECE 380 (Group L2B1)

To: David Michelson, Associate Professor, UBC

From: Evan Huang, Student

Date: February 9^th, 2014

Subject: Weekly Review

Dr. Michelson,

During the third week of the spectrum analyzer project we’ve made some progress in implementing and developing the hardware components of our circuit.  For the resolution bandwidth filter we’ve researched and built a crystal ladder filter with an expected1.5 kHz band pass, to cut noise and other signals out of our desired signal.  Thorough testing and analysis has shown that our crystal ladder filter has a band pass slightly less than 1.5 kHz, which is acceptable.  Our group is also implementing a low pass filter with a cutoff frequency of 1.5 kHz.  The low pass filter is fairly simple in design; however our group struggled to practically apply the circuit to cut out noise outside of the 1.5 kHz designed signal.   We’ve ordered several operational amplifiers of various frequencies above 10 MHz and are awaiting their arrival.  The op amps are to be used in building a precision peak detector to minimize the voltage drop between the input and output of the peak detector.

The two group members previously assigned to design the digital portion of our spectrum analyzer are continuing to familiarizing themselves with myDAQ and the LabVIEW software.  Specifics, such as input values and functions, are being considered for the LabVIEW program.  The members are implementing the ramp function and its relationship with the voltage-controlled oscillator (VCO) and the electronic mixer.  Its output would control the sweeping function of the spectrum analyzer.  One of the members expressed a concern with the insufficient amount of time to work with the myDAQ equipment.  Without being able to use the myDAQ outside of the labs we may not have enough time to properly troubleshoot the complete project in the future.

Our group members have come to build a rapport with one another.  We each contribute a certain necessary aspect to the group and the project, sharing both complications and successes.  Our goal for the following week is to complete the hardware design and begin troubleshooting with the given test specifications.  For the software, our goal is to fully develop the ramp and display functions, and begin troubleshooting with mock input signals.

With Regards,

Evan Huang

Memorandum1

Memorandum

(Group L2B1)

To: David Michelson, Associate Professor, UBC

From: Haleh Rezaei, Student

Date: February 2^th, 2014

Subject: Weekly Review

Dear Dr. Michelson,

This week we started the actual implementation of the Spectrum Analyzer.  We started our implementation by dividing the tasks within our group members. Three of the group members are assigned to work on the hardware and two of the members are responsible for the software part of the project. After dividing the tasks , our hardware group started implementing the Peak Detector and also ordering the necessary parts for other blocks of our design project .Our software group got familiar with MyDaQ and Labview . We did not face any significant problem during our implementation.

In the hardware part of the project, we started by implementing the Peak Detector. In order to get the desirable output for the Peak Detector we watched online videos and we looked into some research papers. We implemented our Peak Detector using different Capacitor and Resistor values and tested each combination multiple times to ensure the output is desirable. Then we got familiar with the Logarithmic Amplifier and Crystal Ladder circuits. We also searched online to purchase the necessary hardware parts for our project; however we realized that the cost of our hardware parts are way less than shipping cost, so we talked to other groups in order to purchase the parts together and divide the shipping cost among the groups.

On the software side , our group members got familiar with myDaq and Labview. They got familiar with the user interface and different built –in functions of Labview and myDaq . They also learned the uses of high and low pass filter, shift register, and different logic gates in Labview .

This week we are going to check out some local stores to find our hardware parts and we are going to implement the Crystal ladder circuit. Our software group will start implementing and coding.

With Regards;

Haleh Rezaei