 A modern GE cordless telephone, model 26930 A cordless telephone or portable telephone is a telephone with a wireless handset which communicates via radio waves with a base station connected to a fixed telephone line (POTS) and can only be operated near (typically less than 100 meters) its base station, such as in and around the house. Unlike a standard telephone, a cordless telephone needs household mains electricity to power the base station. The cordless handset is powered by a battery which is recharged by the base station when the handset sits in its cradle. Image File history File links Wiki_letter_w. ...
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The telephone is a telecommunications device which is used to transmit and receive sound (most commonly voice and speech) across distance. ...
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It has been suggested that this article or section be merged with radio frequency. ...
The term base station can be used in the context of land surveying, wireless computer networking, and wireless communications. ...
A telephone line (or just line) is a single-user circuit on a telephone communications system. ...
Plain old telephone service, or POTS, are the services available from analogue telephones prior to the introduction of electronic telephone exchanges into the public switched telephone network. ...
The metre, or meter (symbol: m) is the SI base unit of length. ...
The term base station can be used in the context of land surveying, wireless computer networking, and wireless communications. ...
Several two-story houses located in Lynnwood, WA. A house in Pathanapuram, Kerala (India) A house, a structure used for habitation by people, generally has walls and a roof to shelter its enclosed space from precipitation, wind, heat, and cold. ...
The term cordless literally means without a cord and is generally used to refer to powered electrical or electronic devices that are able to operate from a portable power source (e. ...
Type F Mains power plug & socket The term “mains†usually refers to the general purpose AC electrical power supply (as in “Ive connected the appliance to the mainsâ€). The term is not usually used in the United States and Canada. ...
A transceiver is a device that has a transmitter and receiver which is combined into a one unit. ...
Four double-A (AA) rechargeable batteries In science and technology, a battery is a device that stores chemical energy and makes it available in an electrical form. ...
Modern cordless telephone standards, like PHS and DECT, have blended the once clear-cut line between cordless and mobile telephones by supporting cell handover, various advanced features like data transfer and even, on a limited scale, international roaming. In these deployment models, base stations are maintained by a commercial mobile network operator and users subscribe to the service. The Personal Handy-phone System (PHS), also marketed as the Personal Access System (PAS), is a mobile network system operating in the 1880-1930 MHz frequency band. ...
See http://en. ...
This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
Roaming is a general term in wireless telecommunications that refers to the extending of connectivity service in a location that is different from the home location where the service was registered. ...
A mobile network operator, also known as wireless service provider, wireless carrier, mobile phone operator, or cellular company, is a telephone company that provides services for mobile phone subscribers. ...
Frequencies
In the United States, seven frequency bands have been allocated by the Federal Communications Commission for uses that include cordless phones. These are: It has been suggested that this article or section be merged with Radio waves. ...
The FCCs official seal. ...
- 1.7 MHz (Up to 6 Channels, AM System)[1]
- 27 MHz (allocated in 1980, Up to 10 Channels, FM System)
- 43–50 MHz (allocated in 1986, Up to 25 Channels, FM System, Base Transmitter: 43.72-46.97MHz, Handset Transmitter: 48.76-49.99MHz)
- 900 MHz (902–928 MHz) (allocated in 1990)
- 1.9 GHz (1920-1930 MHz) (developed in 1993 and allocated U.S. in October 2005)
- 2.4 GHz (allocated in 1998)
- 5.8 GHz (allocated in 2003 due to crowding on the 2.4GHz band)
Virtually all telephones now sold in the US use the 900 MHz, 2.4 GHz, or 5.8 GHz bands, though some legacy phones remain in use on the 27 and 43-50 MHz bands. There is no specific requirement for any particular transmission mode on 900, 2.4, and 5.8, but in practice virtually all 900 MHz phones are inexpensive, bare-bones analog models; digital features such as DSSS and FHSS ae generally only available on the higher frequencies. In telecommunication, the term direct-sequence spread spectrum has the following meanings: A system (a) for generating spread-spectrum transmissions by phase-modulating a sine wave pseudorandomly with a continuous string of pseudonoise code symbols, each of duration much smaller than a bit and (b) that may be time-gated...
Frequency-hopping spread spectrum (FHSS) is a spread-spectrum method of transmitting signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver. ...
One must be careful when looking to purchase 5.8 GHz phones. In actuality, only high-end 5.8 GHz hardware transmits both ways on that frequency. Most so-called 5.8 GHz cordless phones transmit from base to phone on the 5.8 GHz and transmit from phone to base on 2.4 GHz or 900 MHz to conserve battery life inside the phone.
The recently allocated 1.9 GHz band is used by the popular DECT phone standard from Europe. See http://en. ...
Performance Manufacturers usually advertise that higher frequency systems improve audio quality and range. Higher frequencies actually have worse propagation in the ideal case, as shown by the basic Friis transmission equation, and path loss tends to increase at higher frequencies as well. More important influences on quality and range are signal strength, antenna quality, the method of modulation used, and interference, which varies locally. The Friis transmission equation is used in telecommunications engineering, and gives the power transmitted from one antenna to another under idealized conditions. ...
Path loss: In a communication system, the attenuation undergone by an electromagnetic wave in transit between a transmitter and a receiver. ...
In telecommunications, and particularly in radio, signal strength is the measure of how strongly a transmitted signal is being received, measured, or predicted, at a reference point that is a significant distance from the transmitting antenna. ...
A Yagi-Uda beam antenna Short Wave Curtain Antenna (Moosbrunn, Austria) A building rooftop supporting numerous dish and sectored mobile telecommunications antennas (Doncaster, Victoria, Australia) An antenna or aerial is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. ...
In telecommunications, modulation is the process of varying a periodic waveform, i. ...
Plain old telephone service landlines are designed to transfer audio with a quality that is just enough for the parties to understand each other. Typical bandwidth is 3.6 kHz; only a fraction of the frequencies that humans can hear, but enough to make the voice intelligible. No phone can improve on this quality, as it is part of the phone system itself. Higher-quality phones can transfer this signal to the handset with less interference over a greater range, however. Most cordless telephones though, no matter what the frequency band used, or the transmission method, will hardly ever exactly match the sound quality of a high quality wired telephone attached to a good phone line. This can be caused by a number of issues including...1. a digital sidetone, where one hears there own voice echoed in the reciever speaker. 2. A noticible amount of constant background noise. (This is not interference from outside souces, but noise within the cordless telephone system itself.) 3. Frequency response not being the full frequency response available in a wired landline telephone. There has been the rare exception however where a certain cordless telephone sounds indistinguishable from a quality wired landline telephone, but this is very rare. Usually these are rare examples of a particular phone model, thereby being a 'fluke" rather than the norm. A landline or main line is a telephone line which travels through a solid medium, either metal wire or optical fibre. ...
This article or section does not cite its references or sources. ...
Most manufacturers claim a range of about 30 m (100 ft) for their 2.4 GHz and 5.8 GHz systems, but inexpensive models often fall short of this claim.
However, the higher frequency often brings advantages. The 900 MHz and 2.4 GHz band are increasingly being used for a host of other devices including baby monitor, microwave oven, Bluetooth, wireless LAN; thus, it is likely that the cordless phone will suffer interference from signals broadcast by those devices. It is a common misconception that it interferes with the 802.11a wireless standard, as the 802.11a standard operates most commonly in the 5.180 GHz to 5.320 GHz band whereas this is 5.8 GHz. However, 802.11a devices can operate in the 5.8GHz range if configured to do so. A typical baby monitor, sometimes also known as a baby alarm, is a simplex (uni-directional) radio transmitter and receiver system used to remotely listen for noises made by an infant. ...
It has been suggested that this article be split into articles entitled Microwave oven and Microwave heating. ...
Bluetooth logo Bluetooth is an industrial specification for wireless personal area networks (PANs). ...
The notebook is connected to the wireless access point using a PCMCIA wireless card. ...
IEEE 802. ...
IEEE 802. ...
IEEE 802. ...
The recently allocated 1.9 GHz band is reserved for use by phones that use the DECT standard, which should avoid interference issues that are increasingly being seen in the unlicensed 900 MHz, 2.4 GHz, and 5.8 GHz bands. See http://en. ...
The industrial, scientific and medical (ISM) radio bands were originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes. ...
Security Many analog phone signals are easily picked up by radio scanners, allowing anyone within range to listen in on conversations (though this is illegal in many countries). Though many such analog models are still produced, modern digital technology is available to reduce the risk of eavesdropping. Digital Spread Spectrum (DSS) typically uses frequency hopping to spread the audio signal (with a 3 kHz bandwidth) over a much wider range of frequencies in a pseudorandom way. Spreading the signal out over a wider bandwidth is a form of redundancy, and increases the signal-to-noise ratio, yielding longer range and less susceptibility to interference. Higher frequency bands provide more room for these wide-bandwidth signals. A scanner is a radio receiver that automatically tunes, or scans, 2 or more discrete frequencies. ...
Eavesdropping is the intercepting of conversations by unintended recipients. ...
Spread-spectrum telecommunications is a technique in which a signal is transmitted in a bandwidth considerably greater than the frequency content of the original information. ...
Frequency-hopping spread spectrum (FHSS) is a spread-spectrum method of transmitting signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver. ...
A pseudo-random number is a number belonging to a sequence which appears to be random, but can in fact be generated by a finite computation. ...
Redundancy in information theory is the number of bits used to transmit a message minus the number of bits of actual information in the message. ...
Signal-to-noise ratio (often abbreviated SNR or S/N) is an electrical engineering concept defined as the ratio of a signal power to the noise power corrupting the signal. ...
To an analog receiver like a scanner, a DSS signal sounds like bursts of noise. Only the base unit with the same pseudorandom number generator can receive the signal, and it chooses from one of thousands of such unique generators each time the handset is returned to the cradle. A pseudorandom number generator (PRNG) is an algorithm that generates a sequence of numbers which are not truly random. ...
Additionally, the digital nature of the signal increases its tolerance to noise, and some even encrypt the digital signal for even more security. This article is about algorithms for encryption and decryption. ...
Wireless phone handsets Wireless phone handsets exist, designed for connection with a local wired service, not using traditional mobile phone networks, most commonly using digital technologies: namely, DECT, 2.4 GHz unlicensed spectrum,or 802.11a/b/g standards-based wireless LAN technology. The wireless phone handset (per definition) must connect to a wireless access point or base station that supports the same technology. Also required is a call management function and a gateway to the public switched telephony network (PSTN), this may or may not be integrated in the base-station. Analog equivalents do exist and can provide longer reach, but with potential loss of confidentiality and voice quality. Most digital systems have inherent encryption or offer optional encryption. See http://en. ...
IEEE 802. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
The term base station can be used in the context of land surveying, wireless computer networking, and wireless communications. ...
The public switched telephone network (PSTN) is the concatenation of the worlds public circuit-switched telephone networks, in much the same way that the Internet is the concatenation of the worlds public IP-based packet-switched networks. ...
This article is about algorithms for encryption and decryption. ...
History George Harry Sweigert, an amateur radio operator and inventor from Cleveland, Ohio, submitted a patent application in 1966 for the cordless phone. The US Patent and Trade Office awarded him a patent in June of 1969 (see Patents). Sweigert's working model of the first cordless phone was submitted to the Inventor's Hall of Fame in Akron, Ohio. Sweigert, a radio operator in World War II stationed at the South Pacific Islands of Guadalcanal and Bouganville, developed the full duplex concept for non-trained personnel to improve battlefield communications for senior commanders. He was also licensed as W8ZIS and N9LC in the ham radio service.
Sweigert was an active proponent for directly coupling consumer electronics to the A.T.& T. owned telephone lines in the late 1960's (which was banned at the time). The Carterphone, a crude device for interconnecting a two-way radio with the telephone, led to the reversal of the Federal Communications Commission ban on direct coupling of consumer equipment to phone lines (known as the 1968 landmark Carterphone decision) on June 26, 1968.
This is a device which was invented by Thomas Carter. ...
Patents - U.S. Patent 174,465 — Telegraph — A. G. Bell
- U.S. Patent 3,449,750 — Duplex Radio Communication and Signalling Appartus — G. H. Sweigert
- Google Patent Search Link - 3,449,750 [2]
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DCTS, or Defense Collaboration Tool Suite. ...
World map showing North America A satellite composite image of North America. ...
The Personal Handy-phone System (PHS), also marketed as the Personal Access System (PAS), is a mobile network system operating in the 1880-1930 MHz frequency band. ...
It has been suggested that this article or section be merged with Radio waves. ...
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