Nguyên tắc truyền radio

The Future is Wireless A Typical Day in the Year 2000 Joe Mobilus is a manager with a haulage firm in a city 100 km away from his home town; his wife Sue is a nurse at the local hospital. Their son Tom and daughter Ann are still at school. 06:30 The central alarm system wakes Joe and Sue in line with their weekly schedule. 07:00 Joe uses his TETRA terminal to access his firm’s central computer to see if there have been any changes to his diary. 07:15 Joe leaves his house and using his cellular phone in the...

4p huggoo 20-08-2010 48 2   Download

UPT—Universal Personal Telecommunication∗ People are becoming more mobile. At the same time they have a greater need to be reachable and to be able to reach others. A variety of different systems that address all the different categories of mobility already exist: • Employees can be reached through a DECT terminal anywhere in their company. • Tradesmen can be called over a Digital Communication System (DCS) within a city. • Business people can be reached over the same telephone number via GSM anywhere in Europe, wherever they are located. ...

32p huggoo 20-08-2010 75 6   Download

Mobile Satellite Communication∗ In principle communications satellites provide the same connectivity as terrestrial (wireless and wireline) networks. The advantages of satellites, such as fast wide-area coverage, flexible transmission parameters and cost independence due to distance, are compared with the disadvantages, such as restricted channel capacity because of the frequencies available, orbital positions, need for line-of-sight connectivity and high initial investment besides relatively long signal propagation times.

57p huggoo 20-08-2010 64 9   Download