| Today's society relies heavily on an invention taken | | | | the distance the sound had to travel. The formula is: |
| for granted: radar. Just about everybody uses radar, | | | | (S/2) X 1100 = D (Half of the total time times 1100 |
| whether they realize it or not. Tens of thousands of | | | | feet per second equals the distance from the origin |
| lives rely on the precision and speed of radar to | | | | to the reflection point) |
| guide their plane through the skies unscathed. Others | | | | Of course, radar is a much more complicated system |
| just use it when they turn on the morning news to | | | | than just somebody shouting and listening for the |
| check the weather forecast. | | | | echo. In fact, modern radar listens not only for an |
| While radar seems to be an important part of our | | | | echo, but where the echo comes from, what |
| everyday lives, it has not been around for long. It | | | | direction the object is moving, its speed, and its |
| was not put into effect until 1935, near World War II. | | | | distance. There are two types of modern radar: |
| The British and the Americans both worked on radar, | | | | continuous wave radar, and pulse radar. |
| but they did not work together to build a single | | | | Pulse radar works like an echo. The transmitter sends |
| system. They each developed their own systems at | | | | out short bursts of radio waves. It then shuts off, |
| the same time. In 1935, the first radar systems are | | | | and the receiver listens for the echoes. Echoes from |
| installed in Great Britain, called the Early Warning | | | | pulse radar can tell the distance and direction of the |
| Detection system. In 1940, Great Britain and the | | | | object creating the echo. This is the most common |
| United States install radar aboard fighter planes, giving | | | | form of radar, and it is the one that is used the most |
| them an advantage in plane-to-plane combat as well | | | | in airports around the world today. |
| as air-to-ground attacks. | | | | Today, radar systems are standard around the |
| Radar works on a relatively simple theory. It's one | | | | country. The United States has the most |
| that everybody has experienced in their lifetime. | | | | sophisticated radar system, both on the ground and |
| Radar works much like an echo. In an echo, a sound | | | | in the sky. On the ground, we track planes, weather, |
| is sent out in all directions. When the sound waves | | | | ships, and many Intercontinental Ballistic Missiles. From |
| find an object, such as a cliff face, they will bounce | | | | space, we use satellites with radar to map the globe, |
| back to the source of the echo. If you count the | | | | spy on foreign countries, and track over the oceans. |
| number of seconds from when the sound was made | | | | In each instance, radar plays a key role in our |
| to when the sound was heard, you can figure out | | | | day-to-day lives. |