February 23, 2014

To: Dr. David Michelson

From: Ryan Wong, team leader

This memorandum serves as an update for progress of the EECE 380 Design Studio III team, L2C4, during the week of February 24 – March 3, 2014.

This weed, we focused mostly on integrating the hardware component with the software component.

Updates on Hardware Portion:

There was much progress on the hardware, finally completing a design for an amplifier that worked at high frequencies. The team constructed a series of three LM7171 inverting amplifiers with an overall gain of 45 dBm. Our implementation of the subsystem block diagrams from the output of the mixer  involved the 10.7MHz BPF, Crystal Filter, cascaded op-amps, peak detector, active LPF, and voltage divider. From there, our filtered DC signal entered into the myDAQ cleanly.

 

Updates on Software Portion:

This week, we focused mostly on adding extra features to the software portion, as well as integrating it with the hardware component. We played around with the ramp generator to determine the optimal range of frequencies that would produce the more accurate signal, which we decided was between 0.1 to 0.5 Hz. Any frequencies above 0.5 Hz generated a very wide signal that was significantly shifted to the right. We also implemented a means for the user to enter the desired center frequency and the span from the front panel, by using a numeric control and a dial. From these values we were able to determine upper and lower frequencies that we plugged into the X Span and Y Span property nodes of the XY Graph to enable the user to zoom in and out of the graph. We also implemented an algorithm that resets the XY graph after every cycle of the ramp generator. This way, the VI would no longer have buffer issues.

Thus far, the software portion has the following capabilities:

• Determine  the maximum signal power and store it in a shift register, while continuously comparing the maximum value with the current measured power values. Display the maximum signal on the front panel and reset after every ramp cycle.
• Determine the corresponding frequency of the signal detected, store it in a shift register and display on the front panel. Reset after every ramp cycle.
• Count the number of significant signals in one ramp cycle and use this number to determine the modulation index up to 1.5.

We are currently in the process of calibrating the dBm measurements on LabView.