HOME TheInfoList.com
Providing Lists of Related Topics to Help You Find Great Stuff

picture info

Wireless Telephone
A cordless telephone or portable telephone is a telephone in which the handset is portable and communicates with the body of the phone by radio, instead of being attached by a cord. The base station is connected to the telephone network through a telephone line as a corded telephone is, and also serves as a charger to charge the handset's batteries. The range is limited, usually to the same building or some short distance from the base station. The base station on subscriber premises is what differentiates a cordless telephone from a mobile telephone. Current cordless telephone standards, such as PHS and DECT, have blurred the once clear-cut line between cordless and mobile telephones by implementing cell handoff (handover); various advanced features, such as data-transfer; and even, on a limited scale, international roaming
[...More...]

picture info

Mobile Phone
A mobile phone, cell phone, cellphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Modern mobile telephone services use a cellular network architecture, and, therefore, mobile telephones are called cellular telephones or cell phones, in North America. In addition to telephony, 2000s-era mobile phones support a variety of other services, such as text messaging, MMS, email, Internet
Internet
access, short-range wireless communications (infrared, Bluetooth), business applications, video games, and digital photography
[...More...]

picture info

Antenna (radio)
In radio, an antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver.[1] In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplified. Antennas are essential components of all radio equipment, and are used in radio broadcasting, broadcast television, two-way radio, communications receivers, radar, cell phones, satellite communications and other devices. An antenna is an array of conductors (elements), electrically connected to the receiver or transmitter
[...More...]

picture info

AM Broadcast
AM broadcasting
AM broadcasting
is a radio broadcasting technology, which employs amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmissions, but also on the longwave and shortwave radio bands. The earliest experimental AM transmissions were begun in the early 1900s. However, widespread AM broadcasting
AM broadcasting
was not established until the 1920s, following the development of vacuum tube receivers and transmitters
[...More...]

Voice Inversion
Voice Inversion scrambling is an analog method of obscuring the content of a transmission. It is sometimes used in public service radio, automobile racing, cordless telephones and the Family Radio Service. Without a descrambler, the transmission makes the speaker "sound like Donald Duck". It is called "voice inversion", but the technique operates on the passband of the information and so can be applied to any information being transmitted. There are various forms of voice inversion which offer differing levels of security. Overall, voice inversion scrambling offers little true security as software and even hobbyist kits are available from kit makers for scrambling and descrambling. The cadence of the speech is not changed
[...More...]

picture info

Eavesdropping
Eavesdropping
Eavesdropping
is secretly listening to the private conversation of others without their consent, as defined by Black's Law Dictionary.[1] The practice is commonly believed to be unethical.Contents1 Etymology 2 Techniques 3 Network attacks 4 See also 5 References 6 External linksEtymology[edit] The verb eavesdrop is a back-formation from the noun eavesdropper ("a person who eavesdrops"), which was formed from the unrelated noun eavesdrop ("the dripping of water from the eaves of a house; the ground on which such water falls").[2] An eavesdropper was someone who stands at the eavesdrop (where the water drops, i.e., next to the house) so as to hear what is said within
[...More...]

picture info

Baby Monitor
A baby monitor, also known as a baby alarm, is a radio system used to remotely listen to sounds made by an infant. An audio monitor consists of a transmitter unit, equipped with a microphone, placed near to the child. It transmits the sounds by radio waves to a receiver unit with a speaker carried by, or near to, the person caring for the infant. Some baby monitors provide two-way communication which allows the parent to speak back to the baby (parent talk-back). Some allow music to be played to the child. A monitor with a video camera and receiver is often called a baby cam. One of the primary uses of baby monitors is to allow attendants to hear when an infant wakes, while out of immediate hearing distance of the infant
[...More...]

picture info

Direct-sequence Spread Spectrum
In telecommunications, direct-sequence spread spectrum (DSSS) is a spread spectrum modulation technique used to reduce overall signal interference. The spreading of this signal makes the resulting wideband channel more noisy, allowing for greater resistance to unintentional and intentional interference.[1] A method of achieving the spreading of a given signal is provided by the modulation scheme. With DSSS, the message signal is used to modulate a bit sequence known as a Pseudo Noise (PN) code; this PN code consists of a radio pulse that is much shorter in duration (larger bandwidth) than the original message signal. This modulation of the message signal scrambles and spreads the pieces of data, and thereby resulting in a bandwidth size nearly identical to that of the PN sequence.[1] In this context, the duration of the radio pulse for the PN code is referred to as the chip duration
[...More...]

picture info

Frequency-hopping Spread Spectrum
Frequency-hopping spread spectrum
Frequency-hopping spread spectrum
(FHSS) is a method of transmitting radio signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver. It is used as a multiple access method in the code division multiple access (CDMA) scheme frequency-hopping code division multiple access (FH-CDMA) . FHSS is a wireless technology that spreads its signal over rapidly changing frequencies. Each available frequency band is divided into sub-frequencies. Signals rapidly change ("hop") among these in a pre-determined order. Interference at a specific frequency will only affect the signal during that short interval. FHSS can, however, cause interference with adjacent direct-sequence spread spectrum (DSSS) systems
[...More...]

picture info

Conference Call
A conference call is a telephone call in which someone talks to several people at the same time. The conference calls may be designed to allow the called party to participate during the call, or the call may be set up so that the called party merely listens into the call and cannot speak. It is sometimes called ATC (audio tele-conference). Conference calls can be designed so that the calling party calls the other participants and adds them to the call; however, participants are usually able to call into the conference call themselves by dialing a telephone number that connects to a "conference bridge" (a specialized type of equipment that links telephone lines). Companies commonly use a specialized service provider who maintains the conference bridge, or who provides the phone numbers and PIN codes that participants dial to access the meeting or conference call
[...More...]

picture info

Friis Transmission Equation
The Friis transmission formula is used in telecommunications engineering, equating the power at the terminals of a receive antenna as the product of power density of the incident wave and the effective aperture of the receiving antenna under idealized conditions given another antenna some distance away transmitting a known amount of power.[1] The formula was presented first by Danish-American radio engineer Harald T. Friis in 1946.[2] The formula is sometimes referenced as the Friis transmission equation.Contents1 Friis' original formula 2 Contemporary formula 3 See also 4 Sources of further information 5 References 6 External linksFriis' original formula[edit] Friis' original idea behind his transmission formula was to dispense with the usage of Directivity
Directivity
or Gain when describing antenna performance
[...More...]

Path Loss
Path loss (or path attenuation) is the reduction in power density (attenuation) of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system. This term is commonly used in wireless communications and signal propagation. Path loss may be due to many effects, such as free-space loss, refraction, diffraction, reflection, aperture-medium coupling loss, and absorption. Path loss is also influenced by terrain contours, environment (urban or rural, vegetation and foliage), propagation medium (dry or moist air), the distance between the transmitter and the receiver, and the height and location of antennas.Contents1 Causes 2 Loss exponent 3 Radio engineer formula 4 Prediction 5 Examples 6 See also 7 References 8 External linksCauses[edit]This section does not cite any sources
[...More...]

Signal Strength
In telecommunications, particularly in radio frequency, signal strength (also referred to as field strength) refers to the transmitter power output as received by a reference antenna at a distance from the transmitting antenna. High-powered transmissions, such as those used in broadcasting, are expressed in dB-millivolts per metre (dBmV/m). For very low-power systems, such as mobile phones, signal strength is usually expressed in dB-microvolts per metre (dBµV/m) or in decibels above a reference level of one milliwatt (dBm)
[...More...]

picture info

Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. Most radio systems in the 20th century used frequency modulation (FM) or amplitude modulation (AM) to make the carrier carry the radio broadcast. In general telecommunications, modulation is a process of conveying message signal, for example, a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted. Modulation
Modulation
of a sine waveform transforms a narrow frequency range baseband message signal into a moderate to high frequency range passband signal, one that can pass through a filter. A modulator is a device that performs modulation. A demodulator (sometimes detector or demod) is a device that performs demodulation, the inverse of modulation
[...More...]

picture info

DECT 6.0
Digital Enhanced Cordless Telecommunications
Digital Enhanced Cordless Telecommunications
(Digital European Cordless Telecommunications), usually known by the acronym DECT, is a standard primarily used for creating cordless telephone systems. It originated in Europe, where it is the universal standard, replacing earlier cordless phone standards, such as 900 MHz CT1 and CT2.[1] Beyond Europe, it has been adopted by Australia, and most countries in Asia
Asia
and South America. North American adoption was delayed by United States radio frequency regulations. This forced development of a variation of DECT, called DECT 6.0, using a slightly different frequency range which makes these units incompatible with systems intended for use in other areas, even from the same manufacturer
[...More...]

Plain Old Telephone Service
Plain old telephone service or plain ordinary telephone service (POTS) is a retronym for voice-grade telephone service employing analog signal transmission over copper loops.[1] POTS was the standard service offering from telephone companies from 1876 until 1988[2] when the Integrated Services Digital Network
Integrated Services Digital Network
(ISDN) Basic Rate Interface (BRI) was introduced, followed by cellular telephone systems, and voice over IP (VoIP). POTS remains the basic form of residential and small business service connection to the telephone network in many parts of the world
[...More...]

.