1st generation

Long Distance Communications

Telecommunication is the process of long distance communications.
Early telecommunications involved smoke, flags, drums, and other such methods to relay messages and information.
Telegraph :
The first wire line communications was the telegraph. Invented in  the mid 19 th
century, it opened a new era in long-distance telecommunication.
Telephone :
When we talk over the telephone, our voice is converted to an  electronic signal by the microphone in handset. This signal is then transmitted  over telephone wires
Telephone Networks Early Switching Devices: Switches are devices that cause a connection between two transmitting/receiving devices.
Modern Switching Devices :
Today many different types of automated switches are used
which make it possible for fast placement of calls.
Types of telephones:
- Fixed (PSTN) telephones
- Cordless Telephones
- Mobile Telephones
Modes OF Transmission in wireless: 
1-  Simplex communication system
 Example: Television , radio.
2- Half – Duplex communication system
Example : Police radio
3- Full – Duplex communication system
Example : GSM mobile radio

Simple growth was the single transmitting/receiving station :
-heavy, bulky and expensive.
-no switching between regions
-low quality
-limited capacity
-rapid market saturation
-power hungry transceiver
-power level was not safe

- First generation cellular system :
-Introduction of analog cellular systems in the late 1970 s and 1980 s
-analog system
-incompatible systems
-limited to voice service
-no encryption
-FM modulation
-FDMA transmission technology
-suffer from capacity saturation