The Global Positioning System

35. WRITING. Link each set of sentences to make one sentence. You may omit, change or add words as required. Then form your sentences into two paragraphs to make a description of how the GPS works and its uses.

1. The GPS was developed by the US military.

It was designed to pinpoint locations.

The locations could be anywhere in the world.

2. It consists of 24 earth-orbiting satellites.

The satellites are 17,000 km above the earth.

3. Each satellite broadcasts a coded radio signal.

The signal indicates the time and the satellite's exact position.

4. The satellites have atomic clocks.

The clocks are accurate to one second every 70,000 years.

5. A GPS receiver contains a microprocessor.

The microprocessor compares signals.

The signals are from at least three satellites.

The microprocessor calculates the latitude, longitude and altitude of the receiver.

6. GPS has many uses apart from military uses.

GPS can be used for orienting hikers.

GPS can be used for aiding the navigation of ships.

GPS can be used for tracking trucks and buses.

GPS can be used for locating stolen cars.

35. Write (min. 15-20 sentences) about advantages and disadvantages of:

· Mobile phones;

· ADSL internet;

· GPRS system.