Cordless Technology
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Cordless phones allow wireless communication between a portable handset and a base station connected to a telephone line. There are different generations of cordless phone technology, from early analog systems to newer digital standards like DECT and PHS. DECT is widely used in Europe and other parts of the world for home and office cordless phone systems, offering better voice quality and security than analog predecessors. Digital systems also provide features like extended battery life and range compared to early cordless phones.
Cordless Technology
- 2. Cordless system is basically general term of cordless telephones and cordless telecommunication systems.
- 3. Cordless" originates from the technique that made it possible for subscribers to connect a small base station to their telephones, thereby attaining a limited degree of mobility It is full duplex communication systems that use radio to connect a portable handset and a dedicated Base Station, which is then connected to a dedicated telephone line with a specific telephone number on a Public Switched Telephone Network (PSTN).
- 4. Cordless telephone is a telephone with a wireless handset that communicates via radio waves with a base station connected to a fixed telephone line, usually within a limited range of its base station (which has the handset cradle). There are various generations CT0,CT1,CT2,DECT and PHP. of cordless system
- 5. A jazz musician named Teri Pall invented a version of the cordless phone in 1965 but could not market her invention as its twomile range caused radio signals to interfere with aircraft . George Sweigert, an radio operator and inventor from is largely recognized as the father of the cordless phone. He submitted a patent application in 1966 for a "full duplex wireless communications apparatus". Since the 1980s, several companies have entered the cordlessphone market: VTech, Uniden, Philips, Gigaset and Panasonic. They advertise many new features, a few provided by the phone and most provided by the network. Sweigert, a radio operator in World War II stationed at the South Pacific Island developed the full duplex-concept for untrained personnel, to improve battlefield communications for senior commanders. In the 1980s, a number of manufacturers, including Sony, introduced cordless phones for the consumer market.
- 6. Used by Earliest analog models 5 channels No longer in production Very susceptible to interference from fluorescent lights and nearby automobile ignition systems quite crowded, depending on the density of users in a given area have a huge installed base shorter antennas up to 30 auto selecting channels higher resistance to interference 3 varieties: analog, analog spread spectrum (100Khz bandwidth), digital, and digital spread spectrum Allocated on 1993 Few radio scanners cover this band Analog and digital spread spectrum models are available to ensure privacy 1.7 MHz 43 MHz–50 MHz 900 MHz (902 MHz - 928 MHz ) Allocated on 1984 Enjoys 80 channels newer models readily identified by their shorter nontelescoping antennas much less crowded than the 46-MHz to 47-MHz band FM System used by the popular DECT phone standard more secure than the other shared frequencies. 1.9 GHz Contains a huge installed base of analog models Low-power walk-talkies and baby monitors share this same frequency band of 25 channels Some models use audio inversion for scrambling
- 7. Analog Cordless Phones CT0 CT1 Digital Cordless Phones DECT PHS The main distinction among types of cordless phones is the way to transmit their signals.
- 8. These are least expensive Better voice quality than digital Phones Use 5.8 GHz frequency band
- 9. Are of shorter rang than digital phones This is not a secure transmission We can listen voices by using RF scanner (Radio Frequency) or any comparable device Conference calls are not allowed
- 10. Analog phones are typically more open to outside interference, and their sound quality is not as good as that of digital cordless models. Analog cordless signals are easily intercepted by many radio scanners. Digital cordless phones, on the other hand, have a much better sound quality than analog phones, and their signals are much more secure. Many digital phones manufactured after 1995 included digital spread spectrum (DSS) technology, which spreads a phone's signal out over several frequencies in pieces. This feature made it nearly impossible to intercept a cordless phone's signal.
- 11. CT1 - Cordless telephone generation 1 CT1 uses two radio frequencies and analogue technology to provide a full duplex speech path between the handset and the base station. The two frequencies are spaced well apart; in the direction base to handset the frequency is 1.7 MHz, and in the direction handset to base the frequency is 47 MHz. The CT1 system has a number of disadvantages: o o o o The quality of the received speech is not very good. Transmissions can be received by a sound broadcast radio receiver. Only eight R. F. channels are allocated. A telephone has no ability to search for a free channel and hence it can easily be blocked off by another cordless telephone that has been set to use the same channel. o The range is limited to about 50 m.
- 12. Beyond Europe, it has been adopted by Australia, and most countries in Asia and South America. DECT is used primarily in home and small office systems, but is also available in many PBX systems for medium and large businesses.
- 13. Domestic cordless telephony, using a single base station to connect one or more handsets to the public telecoms network. Enterprise premises cordless PABXs and wireless LANs, using many base stations for coverage. Calls continue as users move between different coverage cells, through a mechanism called handover. Calls can be both within the system and to the public telecoms network. Public access, using large numbers of base stations to provide high capacity building or urban area coverage as part of a public telecoms network.
- 14. DECT has also been used for Fixed Wireless Access as a substitute for copper pairs in countries such as India and South Africa. By using directional antennas and sacrificing some traffic capacity, coverage could extend to over 10 km. The standard is also used in electronic cash terminals, traffic lights, and remote door openers
- 15. Multiple handsets to one base station and one phone line socket. This allows several cordless telephones to be placed around the house, all operating from the same telephone jack. Interference-free wireless operation to around 100 meters (109 yards) outdoors, much less indoors when separated by walls . For instance, generally immune to interference from other DECT systems, Wi-Fi networks, video senders, Bluetooth technology, baby monitors and other wireless devices.
- 16. Talk time several hours and standby time of several days on one battery charge. Some systems offer: ● A longer range between the telephone and base station (usable further from the base). ● 24 hours. Extended battery talk-time, sometimes up to
- 17. o Developed in Japan as a cordless telecommunication system o Operates on 1895 MHz-1918MHz o In mid 1990s, UTStarcom introduce IP-based access system(iPAS) o iPAS network is - Low-cost - Easy to deploy - Wireless alternative of copper wire - Portable - Support 55 million subscribers globally personal