Question

help please will medal



Select all that apply.

Which of the following were developed during World War II?

Decca
LORAN
Sonar
Sofar
Radio Direction Finder
@haleyelizabeth2017

@sopeyflytyguy

@crissy15

Answer 1

@lizz123

Answer 2

I think Sonar was.....not sure about the other ones.....I will do some research :)

Answer 3

Decca was....
"The Decca Navigator System was a hyperbolic radio navigation system which allowed ships and aircraft to determine their position by receiving radio signals from fixed navigational beacons. The system used low frequencies from 70 to 129 kHz. It was first deployed by the Royal Navy during World War II when the Allied forces needed a system which could be used to achieve accurate landings. After the war it was extensively developed around the UK and later used in many areas around the world."

from-wiki

Answer 4

LORAN was too....

"LORAN, short for long range navigation,[N 1] was a hyperbolic radio navigation system developed in the United States during World War II. "

-wiki

Answer 5

Sonar was not......that was WW1, not 2

Answer 6

I do not think sofar was.....

"The SOFAR channel (short for Sound Fixing and Ranging channel), or deep sound channel (DSC),[1] is a horizontal layer of water in the ocean at which depth the speed of sound is at its minimum. The SOFAR channel acts as a waveguide for sound, and low frequency sound waves within the channel may travel thousands of miles before dissipating.[2] This phenomenon is an important factor in submarine warfare. The deep sound channel was discovered and described independently by Dr. Maurice Ewing, and Leonid Brekhovskikh in the 1940s.[3]


Sound speed as a function of depth at a position north of Hawaii in the Pacific Ocean derived from the 2005 World Ocean Atlas. The SOFAR channel axis is at ca. 750-m depth.
The SOFAR channel is centred on the depth where the cumulative effect of temperature and water pressure (and, to a smaller extent, salinity) combine to create the region of minimum sound speed in the water column. Pressure in the ocean increases linearly with depth, but temperature is more variable, generally falling rapidly in the main thermocline from the surface to around a thousand metres deep, then remaining almost unchanged from there to the ocean floor in the deep sea. Near the surface, the rapidly falling temperature causes a decrease in sound speed, or a negative sound speed gradient. With increasing depth, the increasing pressure causes an increase in sound speed, or a positive sound speed gradient. The depth where the sound speed is at a minimum is called the sound channel axis.

Near Bermuda, the sound channel axis occurs at a depth of around 1000 metres. In temperate waters, the axis is shallower, and at high latitudes (above about 60°N or below 60°S) it reaches the surface.

Sound propagates in the channel by refraction of sound, which makes sound travel near the depth of slowest speed. If a sound wave propagates away from this horizontal channel, the part of the wave furthest from the channel axis travels faster, so the wave turns back toward the channel axis. As a result, the sound waves trace a path that oscillates across the SOFAR channel axis. This principle is similar to long distance transmission of light in an optical fibre.

Mysterious low-frequency sounds, attributed to fin whales (Balaenoptera physalus), are a common occurrence in the channel. Scientists believe fin whales may dive down to this channel and "sing" to communicate with other fin whales many kilometers away.[4]

During World War II, Dr. Maurice Ewing suggested that dropping into the ocean a small metal sphere (called a SOFAR bomb or SOFAR disc), specifically designed to implode at the SOFAR channel, could be used as a secret distress signal by downed pilots.[5]"

-wiki

Answer 7

I do not think the last one either...I think it was developed before WWI...

"A radio direction finder (RDF) is a device for finding the direction, or bearing, to a radio source. The act of measuring the direction is known as radio direction finding or sometimes simply direction finding (DF). Using two or more measurements from different locations, the location of an unknown transmitter can be determined; alternately, using two or more measurements of known transmitters, the location of a vehicle can be determined. RDF is widely used as a radio navigation system, especially with boats and aircraft.

RDF systems can be used with any radio source, although the size of the receiver antennas are a function of the wavelength of the signal - very long wavelengths (low frequencies) require very large antennas, and are generally used only on ground-based systems. These wavelengths are nevertheless very useful for marine navigation as they can travel very long distances and "over the horizon", which is valuable for ships when the line-of-sight may be only a few tens of kilometres. For aerial use, where the horizon may extend to hundreds of kilometres, higher frequencies can be used, allowing the use of much smaller antennas. An automatic direction finder, often tuned to commercial AM radio broadcasters, is a feature of almost all modern aircraft.

For the military, RDF systems are a key component of signals intelligence systems and methodologies. The ability to locate the position of an enemy broadcaster has been invaluable since World War I, and play a key role in World War II's Battle of the Atlantic. It is estimated that the UK's advanced "huff-duff" systems were directly or indirectly responsible for 24% of all U-Boats sunk during the war. Modern systems often used phased array antennas to allow rapid beam shaping for highly accurate results. These are generally integrated into a wider electronic warfare suite.

Several distinct generations of RDF systems have been used over time, following the development of new electronics. Early systems used mechanically rotated antennas that compared signal strengths in different directions, and several electronic versions of the same concept followed. Modern systems use the comparison of phase or doppler techniques which are generally simpler to automate. Modern pseudo-Doppler direction finder systems consist of a number of small antennas fixed to a circular card, with all of the processing occurring in software.

Early British radar sets were also referred to as RDF, which was a deception tactic. However, the terminology was not inaccurate; the Chain Home systems used separate omni-directional broadcasters and large RDF receivers to determine the location of the targets.[1]"

-wiki

Answer 8

kk i found answer

Answer 9

its a,b,d

Answer 10

i kind of think you answerd your own question

Answer 11

Eh?

Answer 12

how did he answer his own question?

Answer 13

So its decca

Answer 14

You choose multiple answers....

Answer 15

but its muilti choice so idk

Answer 16

yea

Answer 17

lol we already got the answers :P thank you though