What is ranging and phasing in echo sounder?

What is ranging and phasing in echo sounder?

Phasing is a method used in echo sounder to determine depth of the sea bottom. In this method the speed of the stylus is kept constant and the range scale is changed from 0-100 mtrs , 100-200 mtrs , 200-300 mtrs and so on. It is important that the echo sounder range changed and regularly checked.

What is range in echo sounder?

Except on digital displays, various range scales can be displayed, ie 0 to 10 metres, 0 to 20 metres, etc. Echo sounders usually operate in the 10 to 55 Khz frequency range. The human ear can only hear sound in the 8 Hz to 18 Khz range.

What is range switch of echo sounder equipment?

An echo sounder will normally have the following controls: Range Switch – to select the range between which the depth is be checked e.g. 0- 50 m, 1 – 100 m, 100 – 200 m etc. Always check the lowest range first before shifting to a higher range.

What is the basic principles of echo sounder?

Echo sounding is based on the principle that water is an excellent medium for the transmission of sound waves and that a sound pulse will bounce off a reflecting layer, returning to its source as an echo.

What is gain in echo sounder?

Time varied gain (TVG) is signal compensation that removes transmission loss effects from echosounder data. Transmission loss is two-way and is due to acoustic beam spreading and absorption in the acoustic medium.

What causes aeration of an echo sounder?

When the sound wave is reflected from the reflected from the air bubbles, it will appear as dots, this is known as aeration. Aeration can be due to pockets of bubble due to heavy weather.

What is Draft setting in echo sounder?

The Draft affects how the antenna height is measured. If the Draft is 0.00 then the antenna height is the distance from the transducer to the antenna. If a Draft is specified, then the antenna height is the distance from the transducer to the antenna, minus the draft.

What are the errors of echo sounder?

Errors of the Echo Sounder The velocity of propagation in water The velocity of acoustic wave changes if temperature, salinity or pressure changes and since velocity is not correct, the depth recorded will be inaccurate.

What is TVG in echo sounder?

What is Pythagoras error?

This occurs when a ship uses separate transmitters for transmission of the sound pulse and reception of the echo. The transmitters are physically separated on either side of the keel or separated along the length of the keel.

How do I know if my echo sounder is correct?

To ensure the correct sound velocity (SV) is used, a bar check should be conducted before the survey commences. The bar check involves lowering a flat plate below the echo sounder transducer to several known depths below the surface and comparing the actual versus measured depth.

What is time varying gain?

Time varied gain (TVG) is signal compensation that is applied by the receiver electronics through analog or digital signal processing. The desired result is that targets of the same size produce echoes of the same size, regardless of target range.

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