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  • Archive for April, 2010

    Week 13-14 | Final Project 3D Audio


    2010 - 04.30

    My final Nature of Code project is creating the effect of 3D audio with only two speakers.   The process to create the effect of 3D audio is to invert the left channel. Next, is  to reduce the amplitude of the left channel and feed into the right channel.  This process is done to the right channel but vice versa.  Next is to add a delay to each the left and right channel.  The last step is to mix the processed audio back into the original audio track.  The effect is a binaural 3D sound field.

    Here is a demonstration of the 3D effect – 3D Sample

    Original Track – Sing, Sing, Sing

    3D Effect – Sing, Sing, Sing

    A sound is placed in the horizontal plane by processing the sound with recorded head-related impulse responses.

    Wildlife Final Presentation


    2010 - 04.28

    http://docs.google.com/present/view?id=dwb68x9_49frgmm4hk

    Using XBee’s for Wildlife Tracking / XBee 900 Range Test


    2010 - 04.24

    Using XBee 900’s for Wildlife Tracking

    Urban Range Test Setup

    We wanted to find out if XBee 900’s could be used as tracking system. Our first test took place at Washington Square Park. We used two XBee Pro 900 RPSMA. Monkey XBee was fitted with a Digi 2 dBi 7 inch omnidirectional antenna. The trackers XBee was also fitted with the same omnidirectional antenna. One person stayed with the trackers XBee at Washington Square Park, while the other person walked north on Fifth Avenue with the monkey XBee. We were able to get a range of .48 kilometers or 1/3 of a mile with the omnidirectional antennas. We then changed the trackers antenna to a 12 dBi Yagi directional antenna. Using the Yagi antenna increased our distance range marginally. We were able to get an additional .09 kilometers or 300 feet from the Yagi. An increased range was a secondary benefit for us.  We used the Yagi antenna mainly to locate the direction of the monkey.

    The second was at Central Park. We repeated the first test to see if the trees and foliage changed our results compared to the urban environment of Washington Square Park and Fifth Avenue.  The distance range was similar to urban test, the real issue is radio interference. We observed packet loss with the XBee’s. This issue is a characteristic of a highly sophisticated networking protocol.  Due to the high radio interference, packets were being resent causing a delay in trying to find the actual direction of the monkey collar.  XBee’s are great for getting you data reliably back and forth.  However, for our purpose we don’t care for data integrity.  We were instead trying to use the XBee’s as radio beacons.  Our conclusion was the XBee’s are not a suitable solution for replacing the current analog tracking system.

    Scout Update


    2010 - 04.16

    For the past 3 weeks I have been working on Scout.   I want to build a small helicopter that uses tilt-rotors.  I am on the 3rd revision of Scout.  I have hit some roads block such as burnt motors and ESC.  The helicopter’s frame fought me tooth and nail.  I had my moments of disappear thinking I would never get Scout to work,  but I kept at it and have had moments of elation that I will persevere. I learned a lot from the whole process.  This design is straight from my head and I am ecstatic to see my ideas in a tangible form.  I am currently on prototype 4 of Scout.  This version of Scout is fully running yet is a Spruce Goose when come to flying.  In my first test flight, I could only get Scout to hop in the air.  The helicopter is simply too heavy to fly.  Before I even ordered a single part I did do my calculation to see if Scout would fly with the motors I chosen.   I arrived with a power to weight ratio of 1.31:1.  This is too close for comfort in terms of getting Scout off the ground.  It does however go like hell on the ground.  I will have to reduce the weight of the aircraft in my fifth revision.  Stay tuned.  Enjoy the video!

    Scout’s First Test from Russell de la Torre on Vimeo.