07-08-2012, 05:02 PM
Modern Digital Communication System
[attachment=30465]
1G (1st generation)
1G (or 1-G) refers to the first-generation of wireless telephone technology, mobile telecommunications. These are the analog telecommunications standards that were introduced in the 1980s and continued until being replaced by 2G digital telecommunications. The main difference between two succeeding mobile telephone systems, 1G and 2G, is that the radio signals that 1G networks use are analog, while 2G networks are digital.
Although both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system, the voice itself during a call is encoded to digital signals in 2G whereas 1G is only modulated to higher frequency, typically 150 MHz and up.
2G (2nd generation)
A. The First Generation System (Analog)
In 1980 the mobile cellular era had started, and since then mobile communications have undergone significant changes and experienced enormous growth. Fig. 2 shows the evolution of the mobile networks. First-generation mobile systems used analog transmission for speech services. In 1979, the first cellular system in the world became operational by Nippon \Telephone and Telegraph (NTT) in Tokyo, Japan. Two years
Advantages
The lower power emissions helped address health concerns.
Going all-digital allowed for the introduction of digital data services, such as SMS and email.
Greatly reduced fraud. With analog systems it was possible to have two or more "cloned" handsets that had the same phone number.
Enhanced privacy. A key digital advantage not often mentioned is that digital cellular calls are much harder to eavesdrop on by use of radio scanners. While the security algorithmsused have proved not to be as secure as initially advertised, 2G phones are immensely more private than 1G phones, which have no protection against eavesdropping.
Disadvantages
In less populous areas, the weaker digital signal may not be sufficient to reach a cell tower. This tends to be a particular problem on 2G systems deployed on higher frequencies, but is mostly not a problem on 2G systems deployed on lower frequencies. National regulations differ greatly among countries which dictate where 2G can be deployed.
[attachment=30465]
1G (1st generation)
1G (or 1-G) refers to the first-generation of wireless telephone technology, mobile telecommunications. These are the analog telecommunications standards that were introduced in the 1980s and continued until being replaced by 2G digital telecommunications. The main difference between two succeeding mobile telephone systems, 1G and 2G, is that the radio signals that 1G networks use are analog, while 2G networks are digital.
Although both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system, the voice itself during a call is encoded to digital signals in 2G whereas 1G is only modulated to higher frequency, typically 150 MHz and up.
2G (2nd generation)
A. The First Generation System (Analog)
In 1980 the mobile cellular era had started, and since then mobile communications have undergone significant changes and experienced enormous growth. Fig. 2 shows the evolution of the mobile networks. First-generation mobile systems used analog transmission for speech services. In 1979, the first cellular system in the world became operational by Nippon \Telephone and Telegraph (NTT) in Tokyo, Japan. Two years
Advantages
The lower power emissions helped address health concerns.
Going all-digital allowed for the introduction of digital data services, such as SMS and email.
Greatly reduced fraud. With analog systems it was possible to have two or more "cloned" handsets that had the same phone number.
Enhanced privacy. A key digital advantage not often mentioned is that digital cellular calls are much harder to eavesdrop on by use of radio scanners. While the security algorithmsused have proved not to be as secure as initially advertised, 2G phones are immensely more private than 1G phones, which have no protection against eavesdropping.
Disadvantages
In less populous areas, the weaker digital signal may not be sufficient to reach a cell tower. This tends to be a particular problem on 2G systems deployed on higher frequencies, but is mostly not a problem on 2G systems deployed on lower frequencies. National regulations differ greatly among countries which dictate where 2G can be deployed.