Методические указания по английскому языку для студентов I курса всех факультетов. Часть 2. Богданова Н.А - 10 стр.

                        TELEGRAPH AND TELEPHONE

      Communication is a set of electrical and electronic means of messaging.
      Electrical means of communication were invented in the 19-th century. They
were telegraph and telephone where information was transmitted by electrical
signals through wires.
      The basis of telegraphy was laid by Shilling in 1832 in Russia. Shilling
designed, the first complex of devices for electrical telegraph communication. In
1837 an American inventor Morse constructed an electromechanical telegraph
apparatus for transmitting and receiving messages by means of a special code. The
transmitter of his apparatus was a telegraph key, the receiver was an electromagnet.
The first telegraph communication line equipped with Morse apparatus was put into
operation in 1844 in the USA.
       Since that time telegraph communication has been improved. Modem means
of telegraph communication are telex and fax. Telex is an international teleprinter
exchange service and fax is phototelegraphy. It is based on the achievements of
electronics, radio engineering, electrical engineering and optics. Fax (abbreviation
of "facsimile") is the system of transmitting stationary flat images using cable radio
relay and satellite communication channels. It is widely used for quick transmission
of central newspapers' texts and photos, documents, schemes and drafts. But for
telex and fax we shouldn't receive the latest news so fast.
       The history of telephone communication goes back to 1876 when an English
inventor Bell designed the first telephone apparatus. The first telephone station was
built in 1878 in the USA. Telephone communication is based on converting sound
vibrations into electrical signals at the microphone, transmitting these signals along
the cable and reconverting them into sound vibrations of speech at the receiver.
Telephone communication with moving objects is performed by means of
radiotelephone. Without radiotelephone we couldn't communicate with ships
aircraft automobiles and other vehicles.
      The first generation of mobile communication systems dates back from the
middle of 1940-s when the Bell Laboratories Research Centre (USA) put forward
an idea of dividing an area into small parts called cells1. Every cell is served by a
transmitter of a limited effective range2 and a limited number of channels. Different
frequences are used in different cells. Several cells are grouped into a cluster3. A