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