Today, an echo sounder determines depth by measuring the time it takes for a sound pulse to travel from a transducer, bounce off the seabed, and return.
Here's a more detailed explanation:
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Sound Pulse Emission: A transducer, located on the hull of a boat or ship, emits a short pulse of sound waves downwards into the water.
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Sound Wave Travel: The sound wave travels through the water column towards the seabed.
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Echo Reception: When the sound wave encounters the seabed, a portion of it is reflected back towards the transducer. This reflected sound wave is the "echo."
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Time Measurement: The echo sounder precisely measures the time interval between the emission of the sound pulse and the reception of the echo.
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Depth Calculation: Using the known speed of sound in water (which varies depending on temperature, salinity, and pressure, but is typically around 1500 meters per second), the echo sounder calculates the distance to the seabed using the following formula:
Depth = (Speed of Sound * Time) / 2
The division by 2 is necessary because the measured time represents the round trip distance (down to the seabed and back up).
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Display and Recording: The calculated depth is then displayed on a screen, often along with a profile of the seabed. Modern echo sounders can also record the data for later analysis and use in creating nautical charts and maps.
In essence, echo sounders are sophisticated timers that use sound waves to accurately measure the depth of water.
