Search results
Results from the WOW.Com Content Network
The Douglas sea scale is a scale which measures the height of the waves and also measures the swell of the sea. The scale is very simple to follow and is expressed in one of 10 degrees. The scale is very simple to follow and is expressed in one of 10 degrees.
Measuring ocean waves by use of marine radars. Wave radar is a type of radar for measuring wind waves.Several instruments based on a variety of different concepts and techniques are available, and these are all often called.
Remote sensing as we know it today started with the first earth orbiting satellite Landsat 1 in 1973. [10] Landsat 1 delivered the first multi-spectral images of features on land and coastal zones all over the world and already showed effectiveness in oceanography, [11] although not specifically designed for it.
A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity.
Online version of Chart No.1 with "Symbols, Abbreviations and Terms" used in nautical charts; Portolan Chart of Gabriel de Vallseca, 1439; The short film "Reading Charts (April 6, 1999)" is available for free viewing and download at the Internet Archive. Nautical charts available online (Nautical Free) Online Nautical Charts Viewer
Most merchant ships carry at least one of each type to ensure adequate target detection and response. [1] For example, the S-band operates better in sea clutter and rain than the X-band, however, the X-band has greater definition and accuracy in clear weather. [1] Radar is a vital navigation component for safety at sea and near the shore.
For the same numerical value of SPL, the intensity of a plane wave (power per unit area, proportional to mean square sound pressure divided by acoustic impedance) in air is about 20 2 ×3600 = 1 440 000 times higher than in water. Similarly, the intensity is about the same if the SPL is 61.6 dB higher in the water.
A simple calculation reveals that a radar echo will take approximately 10.8 μs to return from a target 1 statute mile away (counting from the leading edge of the transmitter pulse (T 0), (sometimes known as transmitter main bang)). For convenience, these figures may also be expressed as 1 nautical mile in 12.4 μs or 1 kilometre in 6.7 μs.