Electronic Communications

Electronic communications describes a process in which two or more computers or devices transfer data, instruction, and information. Today, even the smallest computers and devices communicate directly with one another, with hundreds of computers on a company network, or with millions of other computers around the globe. The Internet provides a means for worldwide communications.

Some communications involve cables and wires; others communicate wirelessly sending signals through the air. A communications systems contain all types of computers and computing devices.

Communications System

Mainframe

ServerGPS

Notebook

Tablet PC

Smart Phone Web

Enabled PDA

Set-Top Boxes

Desktop

The communications channel consists of telephone lines, cable television and other underground lines, microwave stations, and satellites.

Satellite Microwave Stations

Telephone lines, cable television and other underground lines

Successful communications needs:

• A sending device that initiates (begins) an instruction to transmit data, instructions, or information

Sender

• A communications device that connects the sending device to a communications channel (in this case a modem)

Communications device

Successful communications needs:

A communications channel, such as a telephone line, following the rules defined by the protocol being used so that each computer can understand the message on which the data, instruction or information travels.

Communications channel

Successful communications needs:

Successful Communications needs:

• A communications device that connects a communications channel to the receiving device (in this case a modem)

Communications device

Successful Communications needs:

• A receiving device that accepts the transmission of data, instructions, or information

Receiver

Data, instructions, and information travel along a communications channel in either analog or digital form, depending on the type of communications channel. Two examples of communications channels are cable television and telephone lines. Cable television lines use digital signals, while some telephone lines use analog signals.

An analog signal consists of a continuous electrical wave. A digital signal consists of individual electrical pulses that represent bits grouped together into bytes

All Digital Cable

Digital Representation

Digital to Analog Phone Line

Analog Representation

Digital Representation

How does email get from one computer to another?

Step 1:The sending device requests information using either physical transmission media or wireless transmission media

Step 2:When the request leaves the ISP, it travels over T1 lines, microwave stations, earth-based stations, and communications satellites until it reaches the Internet backboneStep 3:

The request travels over T3 lines along the Internet backbone

Step 4:The request travels over T1 lines until it reaches the destination network server

And How Long Does it Take?

Less than a second!

Assignment

Read the cartoon below and write a story about what is happening in the pictures. Each box should be a sentence. Use the knowledge learned from the presentation to write the sentences.