June 4th is going to be a tough deadline to make for this project because I would like to design a PCB for the module that will contain the filters and microcontroller (perhaps a PIC32). I'd like to be able to assemble the PCB at school where I have access to nice equipment and decent soldering irons meaning I need to design and send out the PCBs ASAP (school ends May 22nd). 

Here is my proposed schedule:

• April 23rd - May 5: Breadboard experimentation & Filter design + Proof of concept to show I can use a set of two microphones/filters to measure a distance
• May 5 - May 9: PCB design (send out PCBs to be created on May 9th)
• May 9 - May 15: try not to fail my ECE exams
• May 15 - May 22: Write microcontroller firmware + PCB assembly + cardboard prototype + beacon prototype
• May 22 - June 4: Integrate Module into a basic robot 
• June 4+ (Improvements phase):
  • Design 3D model of module and beacon to be 3D printed
  • Integrate module into a more practical application, i.e.: shopping cart or video robot (I might do this as part of a class I'm taking next semester)

My progress so far has been getting the Hi-Q band pass filters mostly working when hooked up to a function generator (I need to adjust the gain a bit and maybe cascade two of them together). I've also been able to figure out the envelope detector. Here are some pics:

My setup.

At 20kHz the signal is allowed to pass through and the envelope detector puts out about 3.2V.

At 17kHz the signal can be seen to be attenuated on the oscilloscope and the envelope detector only puts out 2.8V.

When I tried to interface this system with my microphones however, everything went awry! I kept getting this weird 20-25kHz signal that seemed to be coming out of nowhere! After looking around the room however, I found the culprit: 

An occupation sensor with ultrasonic transducers on it. Darn. Guess I can't test in this lab. (I guess that also means robots with this module can't be used in rooms with occupancy sensors).