VI. Прочитайте текст и ответьте на вопрос:” What are the peculiarities of communications channels” Communications channels

A communications channel is the physical medium, through which information travels from its source to its destination. A communications channel is rated by its channel capacity or bandwidth and measured in bits per second.

Cable. Cable includes twisted-pair wire and coaxial cable. Twisted-pair wire consists of two strands of insulated copper wire, twisted around each other and covered in another layer of plastic insulation. Much of the world is served by twisted-pair wire, both for voice messages and for modem-transmitted computer data. Coaxial cable consists of insulated copper wire wrapped in a metal shield, then in an external cover. The shield is grounded and prevents the cable from picking up or emitting electrical noise, thus, coaxial cable is much better at resisting noise than twisted-pair wiring.

Fiber-optic cable. Unlike cables that carry data as electrical signals at radio frequencies, fiber-optic (FO) cable uses infrared or visible light to transmit information as laser-generated pulses of light. It carries much more signals than conventional copper wire, which makes transmission of information faster and less expensive than copper wire transmission, and is totally immune to electromagnetic interference.

Wireless communication. There are many situations in which it is difficult to lay wires. Data can be transmitted via electromagnetic waves and satellite links. Microwave earth stations transmit voice and data through the atmosphere as high-frequency radio waves, even if slower than via fiber-optic cable. As microwave signals travel in a straight line from source to destination, to avoid obstructions and the curvature of the earth, they need to be beamed several times by repeater stations situated on top of high places so that the antennas are in line of sight of each other, or by communications satellites. At very high frequencies (VHF) and above, many communications circuits use satellites in geostationary orbits (GEO) around the earth.

VII. Выделите в тексте именные словосочетания с Past Participle в качестве определений левых.

VIII. В каждом предложении выделите субъект и назовите его признаки.

The processor processes data.

The processor processes the input data.

The powerful processor processes the input data.

The antenna receives the signal.

Radar’s antenna receives the transmitted signal.

The circuit includes many elements.

The integrated circuit includes thousands of elements.

Modern integrated circuits include millions of elements.

Very large integrated circuits include millions of circuits.

IX. Дайте русские эквиваленты.

1. The scanner converts the barcode into electrical pulses.

2. The checkout operator scans the item.

3. The barcode is read by the scanner.

4. Users can share software on the server.

5. Digital cameras store images on memory cards.

6. The image is passed to a small LCD screen on the back of the camera.