EXPLORATIONS - Global Positioning System

EXPLORATIONS - Global Positioning System
By Paul Thompson

Broadcast: Wednesday, May 05, 2004

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VOICE ONE:

This is Steve Ember.

VOICE TWO:

And this is Phoebe Zimmermann with the VOA Special English program, EXPLORATIONS. Today we tell about a device¹ you can hold in your hand. It permits you to find your way across mountains, through deserts and across oceans without ever getting lost.

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VOICE ONE:

 
Captain Josiah Cressy
Let us begin back on June twenty-seventh, Eighteen-Fifty-One. We are on the sailing ship, "Flying Cloud," in the Atlantic Ocean. The Flying Cloud is under the command of Captain Josiah Cressy.

For many days now, Captain Cressy has made the huge ship travel at speeds that were not thought possible. The crew is frightened by the speed. No ship in history has ever traveled this fast. The crew also is frightened because the ship is sailing in some of the most dangerous waters in the world.

The Flying Cloud is near Cape² Horn at the end of the South American continent. The weather has been bad for several days. The person responsible for guiding the ship must be able to see the Sun or a star to know the position of the ship. The stormy weather has prevented this for several days.

VOICE TWO:

 
The Flying Cloud
The person who plans the directions for a sailing trip is usually the ship's captain. On the Flying Cloud, however, the captain's wife does this job.

Her name is Eleanor Cressy. She is famous as an expert navigator. She has planned this trip through the dangerous waters near Cape Horn. Many underwater rocks are found here. To guide the ship safely, she must know where the ship is at all times.

Eleanor Cressy must use a method called "Dead Reckoning³" because she has not been able to see the Sun or stars to find the ship's true position. Dead Reckoning is extremely difficult. It is part science, and part estimate⁴.

To find the position of the Flying Cloud, Missus Cressy must use the last known position of the ship. She also has to consider the ship's direction, its speed and the movement of waves or the ocean current.

Here, near Cape Horn, she is permitted no mistakes. Many ships have sunk in this part of the world. Hour after hour, Eleanor Cressy uses mathematics to find the ship's Dead Reckoning position. She does this again and again, carefully searching for mistakes. The lives of the crew and the future of the ship are her responsibility.

VOICE ONE:

Eleanor Cressy demonstrates⁵ her great skill at navigation⁶ the next day. On the morning of June twenty-ninth, Captain Cressy can see Cape Horn, just eight kilometers to the north. The ship is exactly where Eleanor said it should be. It is safe and will continue on to San Francisco, California, faster than any sailing ship ever.

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VOICE TWO:

Eleanor Cressy's job in Eighteen-Fifty-One was important and extremely difficult. The job of navigator did not change much until the middle of the Twentieth Century. At sea or on land, finding⁷ the correct direction to travel has always been a problem.

However, within the past several years, the problem of navigation has greatly changed. Dead Reckoning navigation is a thing of the ancient past. Now, people do not need the skills of Eleanor Cressy to navigate⁸. They can use a simple device that will permit them to navigate anywhere in the world. It uses a technology called "Global Positioning System," or G-P-S.

VOICE ONE:

 
Artist Picture of a GPS Satellite
G-P-S is able to show your exact position on Earth. Weather does not affect the device. Many G-P-S devices⁹ can be held in the hand. Some are larger, and meant to be placed in ships, automobiles¹⁰, trucks, airplanes or other aircraft.

Whatever the size, the device works¹¹ much the same way. The G-P-S device is a radio receiver. It receives information from twenty-four satellites in orbit¹² around the Earth. The satellites are placed so that a G-P-S device on the surface of the Earth can receive information from at least four of the satellites at any time.

VOICE TWO:

A satellite sends information, including the exact time at which it is operating. It also sends information about the position of other satellites.

This information travels from the satellite to the G-P-S device at almost the speed of light. But the satellite is far enough away to permit the device to measure the distance.

The G-P-S device uses the time the information was sent to find its distance from the satellite. The device measures the exact distance to four satellites to establish its position on Earth. The G-P-S device can do this second by second, minute by minute, day after day and arrive an the correct answer all the time.

You can place the device in a ship, a car or other moving vehicle. Then you can watch the position information change as the vehicle moves. In fact, the G-P-S device will give both your direction and the speed you are traveling.

VOICE ONE:

The United States government owns the twenty-four satellites that provide the information for G-P-S. The Department of Defense¹³ controls the satellites.

The first G-P-S satellite system was called NAVSTAR. It was launched¹⁴ in February, Nineteen-Seventy-Eight. The NAVSTAR satellites were created to provide extremely correct navigation information to American military ships and aircraft.

A few years later, President Ronald Reagan signed a document that permitted information from NAVSTAR to be used by anyone. He did this after a Korean Air Lines flight was lost. The Korean airplane had flown by mistake into airspace over the Soviet¹⁵ Union in nineteen-eighty-three. It was shot down by Soviet military aircraft. President Reagan said the American satellite navigation system would help prevent such accidents in the future.

It costs nothing to use the satellite information. All you need is a G-P-S device to receive the information.

The least costly¹⁶ G-P-S devices sell for about one-hundred dollars. The smallest devices can be held in the hand. Devices for aircraft or ships are larger. They may cost several thousands of dollars.

VOICE TWO:

After President Reagan permitted the public use of American navigation information, several electronics¹⁷ companies began making the G-P-S devices. However, there was a problem. The Defense Department would not let the satellites send the exact information to the public. Defense officials made sure the satellites sent information with mistakes. This was done so the information could not be used by military forces of any future enemy.

In May of two-thousand, the United States announced that such a security¹⁸ measure was no longer needed. The government turned off the equipment preventing satellites from providing the correct information.

Today, a G-P-S device that receives information from four satellites at the same time will show your correct position on Earth to within ten meters. It can also tell you the speed of your vehicle, the direction you are traveling, how far you have traveled, and the distance remaining until the end of your trip.

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VOICE ONE:

G-P-S devices are popular in the United States. Many companies make and sell them. Most of the devices come with a receiver that looks like a small television. The less costly G-P-S devices provide information in black and white. More costly ones provide the information in color.

Many G-P-S devices can be linked to computers. The computers place information into the device including maps of city streets and major roads between cities.

The user¹⁹ of the device enters information using the controls. The G-P-S provides information about the direction of travel and tells how to get where you want to go. The device will correctly guide you from road to road and street to street, warning before a left and right turn must be made. The device also remembers where it has been. So it can guide the G-P-S user home again.

Recently, some companies started producing G-P-S devices that speak the directions. A person driving a vehicle does not have to look at the device for information. A person only has to listen. Here is an example. This G-P-S device is from the Garmin Company. Listen as the voice gives directions.

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VOICE TWO:

As you can see, the new G-P-S devices can help anyone get to where they want to go. And, they can do this just as well as the famous Eleanor Cressy did one-hundred-fifty years ago.

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VOICE ONE:

This VOA Special English program was written by Paul Thompson and produced by Caty Weaver²⁰. This is Steve Ember.

VOICE TWO:

And this is Phoebe Zimmermann. Join us again next week for another EXPLORATIONS program on the Voice of America.

(MUSIC)

1 device   

n.器械，装置；计划，策略，诡计

参考例句：

• The device will be in production by the end of the year.该装置将于年底投入生产。
• The device will save much time and effort for us.这种装置会使我们节省大量时间和气力。

2 cape   

n.海角，岬；披肩，短披风

参考例句：

• I long for a trip to the Cape of Good Hope.我渴望到好望角去旅行。
• She was wearing a cape over her dress.她在外套上披着一件披肩。

3 reckoning   

n.结帐；(喻)算帐；惩罚

参考例句：

• Phelan is fit again and could come into the reckoning. 菲兰已经恢复了体力，有可能获胜。
• The reckoning up of revenue and expenditure shows a small surplus. 收支相抵，略有剩余。

4 estimate   

n.估计，估量；评价，看法；vt.估计，估量

参考例句：

• We estimate the cost to be five thousand dollars.我们估计费用为5000美元。
• The lowest estimate would put the worth of the jewel at ＄200.按最低的评估这块宝石也值200美元。

5 demonstrates   

举行示威游行（或集会）( demonstrate的第三人称单数 )； 示范。展示； 显示； 论证

参考例句：

• I hope this message demonstrates my feelings to the students. 我希望这个祝词能表达出我对学生们的感情。
• I hope this demonstrates to you how I feel. 我希望这能向你表明我的感受。

6 navigation   

n.航行；航海；航空

参考例句：

• The compass is an instrument of navigation.罗盘是导航仪器。
• Navigation is difficult on this river because of hidden rocks.由于多暗礁，在这条河上航行很困难。

7 finding   

n.发现，发现物；调查的结果

参考例句：

• The finding makes some sense.该发现具有一定的意义。
• That's an encouraging finding.这是一个鼓舞人心的发现。

8 navigate   

v.航行，飞行；导航，领航

参考例句：

• He was the first man to navigate the Atlantic by air.他是第一个飞越大西洋的人。
• Such boats can navigate on the Nile.这种船可以在尼罗河上航行。

9 devices   

n.设备；装置( device的名词复数 )；花招；（为实现某种目的的）计划；手段

参考例句：

• electrical labour-saving devices around the home 节省劳力的各种家用电器
• modern labour-saving devices such as washing machines and dishwashers 诸如洗衣机和洗碗机之类的现代化省力设备

10 automobiles   

n.汽车( automobile的名词复数 )

参考例句：

• When automobiles become popular,the use of the horse and buggy passed away. 汽车普及后，就不再使用马和马车了。 来自《简明英汉词典》
• Automobiles speed in an endless stream along the boulevard. 宽阔的林荫道上，汽车川流不息。 来自《现代汉英综合大词典》

11 works   

n.作品，著作；工厂，活动部件，机件

参考例句：

• We expect writers to produce more and better works.我们期望作家们写出更多更好的作品。
• The novel is regarded as one of the classic works.这篇小说被公认为是最优秀的作品之一。

12 orbit   

n.轨道；vt.使沿轨道运行；使进入轨道运行；vi.沿轨道运行，环行

参考例句：

• The space rocket was launched and went into orbit.宇宙火箭发射后进入轨道。
• We can draw the earth's orbit round the sun.我们可以画出地球绕太阳运行的轨迹。

13 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

14 launched   

v.发射( launch的过去式和过去分词 )；[计算机]开始（应用程序）；发动；开展（活动、计划等）

参考例句：

• He launched a bitter diatribe against the younger generation. 他对年轻一代发起了猛烈的抨击。
• The product was launched amid much fanfare worldwide. 这个产品在世界各地隆重推出。

15 Soviet   

adj.苏联的，苏维埃的；n.苏维埃

参考例句：

• Zhukov was a marshal of the former Soviet Union.朱可夫是前苏联的一位元帅。
• Germany began to attack the Soviet Union in 1941.德国在1941年开始进攻苏联。

16 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

17 electronics   

n.电子器件，电子学，电子技术

参考例句：

• About 45000 people worked in electronics in Scotland.苏格兰约有4.5万人在电子行业工作。
• He wants to brush up his knowledge of electronics.他想温习他的电子学知识。

18 security   

n.安全，安全感；防护措施；保证(金)，抵押(品)；债券，证券

参考例句：

• A security guard brought him down with a flying tackle.一名保安人员飞身把他抱倒。
• There was tight security at the airport when the President's plane landed.总统的专机降落时，机场的保安措施很严密。

19 user   

n.用户，使用者

参考例句：

• The company is the biggest user of oil.该公司是最大的石油用户。
• The umbrella keeps the rains off the user.雨伞使撑伞人免受雨淋。

20 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。