Laser Listening Device

Posted on Feb 7, 2014

Second, I have found that when the receiver was centered in the brightest spot (middle) of the reflected laser beam the circuit worked poorly compared to when the receiver was placed off-centered. This probably indicated that the circuit was saturated when the receiver was centered. And when it was off-centered, the circuit was able to analyze the

Laser Listening Device
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weaker (less saturated) laser signal better. This must show that the lower energized beam was better able to become modulated when the beam was contacting the sound source. This can be useful in that this can mean that the laser can be sent at a longer distant to work even better. And the thickness of the plane where the sound source is found can also affect the performance of the receivers capability to detect any changes in the signal. The thinner the plane, the easier it will vibrate and the better for the laser to be come modulated. Although it was said that the greater the distance the laser and the sound source the better the chance the laser will diverge larger giving a weaker signal (which prevents the over-saturation of the circuit) there will come limitations to this process. So, using lenses to converge a larger area of the reflected beam to the receiver will help increase the range of the laser snooper even more. It was printed that the range may be as large as 300 feet versus the current 30 feet range. Although this isn`t really an electronic project, one way to think about as a future design is to implement Jake Janovetz`s Napoleon 56K DSP board to filter out background noise. Background noise was very present from the receiver, and using the DSP board might have helped out in making the receiver work even better than it was designed for. This project has helped me relearn the theories learned from ECE342....

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