Echo Sounder Operation and Controls
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Echo Sounder Operation and Controls

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Questions and Answers

What is the primary function of the transducer in an echo sounder?

  • To amplify the received signal
  • To convert electric pulses into sound waves (correct)
  • To display the depth information
  • To generate electric pulses

    • Depth measurement in an echo sounder is calculated using the total distance travelled by the sound pulse.

    False

    What speed is associated with sound waves in seawater?

    1500 m/s

    The control unit in an echo sounder is responsible for generating electric ______ and measuring the time.

    <p>pulses</p> Signup and view all the answers

    Match the following components of an echo sounder with their functions:

    <p>Display Unit = Shows depth reading Transducer = Converts electric pulses to sound waves Control Unit = Generates electric pulses Amplifier = Increases signal strength</p> Signup and view all the answers

    What range of frequencies do echo sounders typically use for sound waves?

    <p>12 KHz to 200 KHz</p> Signup and view all the answers

    Where is the transducer typically located on a ship?

    <p>At the bottom in a transducer compartment or tank</p> Signup and view all the answers

    Digital echo sounders provide a paper recording of depth information.

    <p>False</p> Signup and view all the answers

    Which control is responsible for adjusting the range scale and clutter level according to depth?

    <p>Auto</p> Signup and view all the answers

    The Time Variable Gain (TVG) control is used to increase sensitivity at greater depths.

    <p>False</p> Signup and view all the answers

    What might happen if the Gain control is set too low?

    <p>Not enough echoes may return.</p> Signup and view all the answers

    The control that allows the navigator to set a warning for shallow areas is known as the ______.

    <p>Depth Alarm</p> Signup and view all the answers

    What is the maximum depth that Time Variable Gain (TVG) can work on echo sounders operating at 200 kHz?

    <p>150 m</p> Signup and view all the answers

    Match the control with its function:

    <p>Gain = Adjusts instrument sensitivity Echo Offset = Adjusts the strength of echoes Draught = Allows calculation of available water depth Dimmer Control = Controls screen brightness</p> Signup and view all the answers

    Transducer placement has no impact on the accuracy of depth measurements.

    <p>False</p> Signup and view all the answers

    What impacts the location of the bow wave on a ship?

    <p>The shape of the bow, the speed, and the draught of the ship.</p> Signup and view all the answers

    What should be considered when installing a transducer?

    <p>Minimum interference from engine or propeller vibration</p> Signup and view all the answers

    An increase in temperature, salinity, or pressure results in a decrease in the speed of sound through water.

    <p>False</p> Signup and view all the answers

    What is the assumed speed of sound waves through water for echo sounder calculations?

    <p>1500 m/s</p> Signup and view all the answers

    The indicated depth by an echo sounder may be about ___ less than the actual depth in the Red Sea.

    <p>5%</p> Signup and view all the answers

    Which of the following is an example of an instrument inaccuracy related to echo sounders?

    <p>Speed error</p> Signup and view all the answers

    False echoes are a type of error that can affect the navigational accuracy of an echo sounder.

    <p>True</p> Signup and view all the answers

    What is one method navigators must use to verify echo sounder readings when errors occur?

    <p>Comparing the depth obtained with the chart.</p> Signup and view all the answers

    Match the errors related to echo sounders with their descriptions:

    <p>Speed Error = Result of varying atmospheric conditions affecting sound speed Second Transmission Error = When a previous pulse is mistaken for the current pulse</p> Signup and view all the answers

    What may cause unknown errors in the depth measured in seawater?

    <p>Variations in salinity and temperature</p> Signup and view all the answers

    Sound waves will not be affected if the seabed is horizontal.

    <p>True</p> Signup and view all the answers

    What is a double echo?

    <p>An echo received from sound waves reflected back from the ship's hull and then the seabed.</p> Signup and view all the answers

    The phenomenon where seawater creates bubbles that distort sound waves is known as __________.

    <p>turbulence</p> Signup and view all the answers

    What can navigators do to eliminate the impact of double echoes?

    <p>Change the selected depth or scale</p> Signup and view all the answers

    Match the following types of echoes with their descriptions:

    <p>Double Echo = Reflection causing two displayed layers Multiple Echoes = Sound waves reflected multiple times between surfaces False Echoes = Strong reflections misinterpreted as seabed Pythagoras Error = Measurement error due to distance between transmitter and receiver</p> Signup and view all the answers

    Turbulence and aeration can enhance an echo sounder's capability of depth measurement.

    <p>False</p> Signup and view all the answers

    What is the Pythagoras Error in echo sounders?

    <p>An error caused when the transmitter is located away from the receiver.</p> Signup and view all the answers

    Study Notes

    Echo Sounder Operation

    • An echo sounder sends sound waves to the seabed and measures the time it takes for the sound waves to return.
    • Transducers convert electric pulses into sound waves and vice versa.
    • The speed of sound in seawater is used to calculate depth: Depth = Speed of sound waves x time / 2
    • Display unites show the depth on a paper or digital display.
    • Some echo sounders use different colors on the display to indicate seabed composition.

    Echo Sounder Controls

    • Auto: Automatically adjusts range and clutter level based on depth.
    • Gain: Adjusts the sensitivity of the instrument.
    • TVG (Time Variable Gain): Similar to STC in radar. Reduces surface noise by compensating for sound wave attenuation.
    • Echo Offset: Adjusts weak or strong echoes.
    • Depth Alarm: Warns the navigator when the ship enters shallow water.
    • Draught: Allows the navigator to input the ship's current draught for accurate depth measurements.
    • Dimmer Control: Controls the screen brightness and keypad illumination.

    Transducer Location

    • The transducer should be located in a place with minimal aeration and interference from engine or propeller vibration.
    • The bow of the ship is prone to aeration and should be avoided for transducer placement.

    Echo Sounder Errors

    Instrument Inaccuracies

    • Speed Error: The speed of sound in seawater varies with temperature, salinity, and pressure.
    • Second Transmission Error: In deep water, the echo sounder may receive a delayed echo from the previous transmission,resulting in an inaccurate depth reading.
    • Refraction and Reflection of Sound Waves: Variations in temperature and salinity can cause sound waves to reflect and refract, leading to inaccurate depth readings.
    • Reflection from Sloping Seabed: If the seabed is not horizontal, sound waves may be reflected unevenly, leading to inaccurate or absent depth readings.

    False Echoes

    • Double Echo: Sound waves reflecting off the ship's hull and then the seabed create a double echo on the display.
    • Multiple Echoes: Similar to a double echo, but with multiple reflections between the hull and seabed.
    • Echoes from other objects in seawater: Plankton, fish, or seaweed can produce echoes that the echo sounder may interpret as the seabed.
    • Turbulence and Aeration: Air bubbles caused by turbulence can disrupt echo signals and lead to false readings.
    • Pythagoras Error: When the transducer and receiver are a distance apart, the sound wave travels a longer distance than the direct path to the seabed, leading to an inaccurate measurement. Modern echo sounders are designed to account for this error.

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    Related Documents

    Echo Sounder Operation & Controls PDF

    Description

    This quiz explores the principles and controls of echo sounders used in nautical applications. It covers the operation of echo sounders, including how sound waves measure seabed depth and the various controls that adjust the instrument's performance. Test your knowledge of the key concepts involved in using echo sounders effectively.

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