Building a Sonar System from Scratch

What?
With two classmates, I built a sonar system using a buzzer, a microphone, circuitry, and LabVIEW.
Why?
Lake Waban in Wellesley, Massachusetts is a destination for college students who want to go canoeing or kayaking for free. We wanted to measure the lake at various points to create a rough bathymetric (depth) map of the lake.
How?
Pulses were created by sending a signal from software to a timer chip, and then to a buzzer that emitted a high-frequency click. The response from a waterproof microphone was cross-correlated with the pulse that controlled the buzzer to calculate the time delay, which was proportional to the depth of the lake at that point. A more detailed overview of the process can be read from the flowcharts to the left. We tested our system in Lake Waban from a canoe and performed several successful measurements, though not enough to get a detailed bathymetric map.

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