Explore topic-wise fullforms in Telecommunication

In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver in the absence of a strong input signal. Essentially, squelch is a specialized type of noise gate designed to suppress weak signals. Squelch is used in two-way radios and VHF/UHF radio scanners to eliminate the sound of noise when the radio is not receiving a desired transmitter.

INFO: Full form for CVSD is Continuously Variable Slope, Delta Modulation in Telecommunication category
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INFO: Full form for DSCP is Differentiated Services Control Point in Telecommunication category
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INFO: Full form for DS0 is Digital Signal Zero in Telecommunication category
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INFO: Full form for DID is Digital Information Display in Telecommunication category
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INFO: Full form for DID is Direct Inward Dial in Telecommunication category
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INFO: Full form for DECT is Digital Enhance Cordless Telecommunications in Telecommunication category
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INFO: Full form for DECT is Digitally Enhanced Cordless Telecommunications in Telecommunication category
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INFO: Full form for DDS is Dataphone Digital Service in Telecommunication category
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INFO: Full form for DCN is Data Communications Network in Telecommunication category
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Distributed coordination function (DCF) is the fundamental medium access control (MAC) technique of the IEEE 802.11-based WLAN standard (including Wi-Fi). DCF employs a carrier-sense multiple access with collision avoidance (CSMA/CA) with binary exponential backoff algorithm.

DCF requires a station wishing to transmit to listen for the channel status for a DIFS interval. If the channel is found busy during the DIFS interval, the station defers its transmission. In a network where a number of stations contend for the wireless medium, if multiple stations sense the channel busy and defer their access, they will also virtually simultaneously find that the channel is released and then try to seize the channel. As a result, collisions may occur. In order to avoid such collisions, DCF also specifies random backoff, which forces a station to defer its access to the channel for an extra period. The length of the backoff period is determined by the following equation:

B a c k o f f T i m e = r a n d o m ( ) × a S l o t T i m e {\displaystyle \mathrm {BackoffTime} =\mathrm {random} ()\times \mathrm {aSlotTime} }

DCF also has an optional virtual carrier sense mechanism that exchanges short Request-to-send (RTS) and Clear-to-send (CTS) frames between source and destination stations during the intervals between the data frame transmissions.

DCF includes a positive acknowledge scheme, which means that if a frame is successfully received by the destination it is addressed to, the destination needs to send an ACK frame to notify the source of the successful reception.

DCF does not solve the hidden terminal and/or exposed terminal problem completely, it only alleviates the problem through the use of RTS and CTS, and recommends the use of a larger carrier sensing range.

DCF is defined in the IEEE 802.11 standard and is the de facto default setting for Wi-Fi hardware.

802.11 DCF consumes a significant amount of airtime, 802.11 control messages usually convey very little information. For example, an ACK message can take up to 60 μs to transmit completely, which includes an amount of airtime sufficient to transmit 3240 bits at 54 Mbit/s, during which it conveys a single bit of relevant information.

The IEEE 802.11 standard also defines an optional access method using a point coordination function (PCF). PCF allows the access point acting as the network coordinator to manage channel access. The IEEE 802.11e amendment to the standard enhances the DCF and the PCF, through a new coordination function called Hybrid Coordination Function (HCF).

DAVIC, Digital Audio Video Council, was founded in 1994 with the aim of promoting the success of interactive digital audio-visual applications and services by promulgating specifications of open interfaces and protocols that maximise interoperability, not only across geographical boundaries but also across diverse applications, services and industries. It was a non-profit international organization based in Switzerland.

DAVIC was closed, according to its statutes, after 5 years of activity.

At the most DAVIC had 222 companies from more than 25 countries as members, although over its life 295 organisations were members at some stage. It represented all sectors of the audio-visual industry: manufacturing (computer, consumer electronics and telecommunications equipment) and service (broadcasting, telecommunications and CATV), as well as a number of government agencies and research organisations.

The four major sets of specifications culminated in 1999 with the 1.4 version. The 1.5 version of DAVIC was a set of additional tools and service definitions opening the road towards the setting of IP based audiovisual services such as the TV Anytime and TV Anywhere services. Version 1.3.1 was re-structured and was approved as an ISO/IEC standard and technical report (ISO/IEC 16500 and ISO/IEC TR 16501).

The management of DAVIC had proposed the continuation beyond the 5-year date with a program of work centred on two projects: TV Anytime and TV Anywhere. The membership did not support the continuation of DAVIC but the idea of TV-Anytime continued as a new organisation.

INFO: Full form for DCT is Digital Cordless Telecommunications in Telecommunication category
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A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. The term is derived from Greek: τῆλε (tēle, far) and φωνή (phōnē, voice), together meaning distant voice. A common short form of the term is phone, which came into use almost immediately after the first patent was issued.

In 1876, Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice at a second device. This instrument was further developed by many others, and became rapidly indispensable in business, government, and in households.

The essential elements of a telephone are a microphone (transmitter) to speak into and an earphone (receiver) which reproduces the voice in a distant location. In addition, most telephones contain a ringer to announce an incoming telephone call, and a dial or keypad to enter a telephone number when initiating a call to another telephone. The receiver and transmitter are usually built into a handset which is held up to the ear and mouth during conversation. The dial may be located either on the handset or on a base unit to which the handset is connected. The transmitter converts the sound waves to electrical signals which are sent through a telephone network to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker. Telephones are duplex devices, meaning they permit transmission in both directions simultaneously.

The first telephones were directly connected to each other from one customer's office or residence to another customer's location. Being impractical beyond just a few customers, these systems were quickly replaced by manually operated centrally located switchboards. These exchanges were soon connected together, eventually forming an automated, worldwide public switched telephone network. For greater mobility, various radio systems were developed for transmission between mobile stations on ships and automobiles in the mid-20th century. Hand-held mobile phones were introduced for personal service starting in 1973. In later decades, their analog cellular system evolved into digital networks with greater capability and lower cost.

Convergence has given most modern cell phones capabilities far beyond simple voice conversation. Most are smartphones, integrating all mobile communication and many computing needs.

INFO: Full form for STS is Synchronous Transfer Signal in Telecommunication category
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INFO: Full form for STS is Small Telephone System in Telecommunication category
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INFO: Full form for STN is Satellite Telecommunications Networks in Telecommunication category
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INFO: Full form for TRAC is Totally Reconfigurable Analog Circuit in Telecommunication category
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INFO: Full form for TNS is Telephone Notification System in Telecommunication category
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INFO: Full form for TNS is Terminating Noncritical Section in Telecommunication category
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INFO: Full form for TNS is Time To Next Send in Telecommunication category
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INFO: Full form for TBI is Telecom Brokerage Inc in Telecommunication category
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INFO: Full form for TSS is Telecommunication Standards Sector in Telecommunication category
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The Telephony Application Programming Interface (TAPI) is a Microsoft Windows API, which provides computer telephony integration and enables PCs running Microsoft Windows to use telephone services. Different versions of TAPI are available on different versions of Windows. TAPI allows applications to control telephony functions between a computer and telephone network for data, fax, and voice calls. It includes basic functions, such as dialing, answering, and hanging up a call. It also supports supplementary functions, such as hold, transfer, conference, and call park found in PBX, ISDN, and other telephone systems.

TAPI is used primarily to control either modems or, more recently, to control business telephone system (PBX) handsets. When controlling a PBX handset, the driver is provided by the manufacturer of the telephone system. Some manufacturers provide drivers that allow the control of multiple handsets. This is traditionally called "third-party control". Other manufacturers provide drivers that allow the control of a single handset. This is called "first-party control". Third-party drivers are designed to allow applications to see and/or control multiple extensions at the same time. Some telephone systems only permit one third-party connection at a time. First-party drivers are designed to allow applications to monitor and/or control one extension at a time. Telephone systems naturally permit many of these connections simultaneously. Modem connections are by nature first-party.

TAPI can also be used to control voice-enabled telephony devices, including voice modems and dedicated hardware such as Dialogic cards.

Telecommunications Access Method (TCAM) is an access method, in IBM's OS/360 and successors computer operating systems on IBM System/360 and later, that provides access to terminals units within a teleprocessing network.

INFO: Full form for TEM is Telecommunications Expense Management in Telecommunication category
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