2. Electronic Communications

3. 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.

4. 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.

5. Communications System Mainframe Server GPS 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

6. Successful communications needs: A sending device that initiates (begins) an instruction to transmit data, instructions, or information Sender

7. A communications device that connects the sending device to a communications channel (in this case a modem) Communications device Successful communications needs:

8. 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:

9. Successful Communications needs: A communications device that connects a communications channel to the receiving device (in this case a modem) Communications device

10. Successful Communications needs: A receiving device that accepts the transmission of data, instructions, or information Receiver

11. 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

12. All Digital Cable Digital Representation

13. Digital to Analog Phone Line Analog Representation Digital Representation

15. 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 backbone Step 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

16. And How Long Does it Take? Less than a second!

17. 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.