Long Distance Data Transmission

Equalizers need adjustments after line replacement and periodically, especially for low-quality lines with frequent parameter changes.

Automatically adjusts to line quality changes after initial tuning, usually taking 15-25ms.

Equalizers can be adjusted up to 2400 times per second in some modems.

Transmit data with a clock signal, usually in blocks with framing codes for error detection.

A synchronous modem that can split the channel for multiple users at different speeds.

Communication channels like telephone lines that have limited bandwidth.

Signals representing data as square waves (0s and 1s).

Digital square waves are altered by analog media, causing signal errors.

The process of changing digital signals into analog signals to transmit information through communication channels.

The technique used to convert digital signals into analog signals for communication.

Methods to test the quality and integrity of modem connections.

ITU standard for loopback tests in modems.

Tests the local modem, connecting cable, and serial connector for analog signals.

Tests the connection up to the remote modem, including the carrier connection, with digital signals.

Built-in Bit Error Rate Tester, used to quickly detect transmission problems in remote digital loop test mode.

Extends the digital loop test from the local modem to help isolate problems on the remote side of the communication link.

Testing the quality of T1/E1 links by detecting poor quality links and isolating problems.

Testing used by carriers or ISPs to diagnose and solve connection problems on T1/E1 links.

Modems capable of transmitting and receiving simultaneously at full speed.

A method of full-duplex modem operation where signals for transmission and reception use different frequency bands, separated by filters.

A technique for full-duplex modem operation that eliminates echoes to allow simultaneous transmission and reception.

Modems that allow signals to be passed in only one direction.

Modems that operate at low to moderate speeds (up to 1800 bps), employing FSK modulation and framing bits (start and stop bits) for data synchronization.

Method used to ensure that the transmitting and receiving modems' clocks are aligned for data transfer.

Data transmitted without any embedded clock information; data is organized into distinct blocks for synchronization.

Modems that operate at higher speeds (up to 28800 bps) using phase modulation or phase-amplitude modulation; data transfer is synchronized.

Devices used in synchronous modems to compensate for signal distortion along the telephone lines.

Equalizers set in factory to compensate for average line attenuation on a dial-up line.

Equalizers that can be tuned to compensate for specific line characteristics to optimize performance.

A system for representing text characters (letters, numbers, and symbols) using a unique series of seven bits (ones and zeros).

The rate at which a modem can send and receive data over a telephone line, measured in bits per second (bps).

A modem that communicates at a rate of 56,000 bits per second, adhering to the ITU V.90 standard.

A modem designed for short distances (up to approximately 15 km), primarily for private lines.

A modem using basic modulation methods, often less sophisticated than other types for error control and equalization.

A component in short-haul modems that strengthens the digital signal before transmission over the communication channel, without transmitting a carrier signal.

Equalizers need adjustments after line replacement and regularly, especially for low-quality lines with frequent parameter changes.

Automatically adjusts to line quality changes after initial tuning, typically within 15-25ms.

Equalizers in some modems can be adjusted up to 2400 times a second.

Transmit data with a clock signal, often in blocks with codes for error detection.

A synchronous modem that can divide the channel for multiple users with varying speeds.

Communication channels like phone lines, having limited bandwidth.

Signals that represent data as square waves with values of '0' and '1'.

Digital square waves get altered by analog media, leading to signal errors.

The method of converting digital signals to analog form for communication over analog channels.

The data rate of ADSL is not fixed; it adapts to the local loop cable's condition and bandwidth availability.

The standard modulation technique for ADSL, combining QAM and FDM for bandwidth division.

ADSL divides the available bandwidth (typically 1.104 MHz) into channels for voice, idle, upstream, and downstream data transfer.

Channels 6 to 30 in ADSL, used for data transfer and control from the customer to the central office.

Channels 31 to 255 in ADSL, used for data transfer and control from the central office to the customer.

A device used at the customer's site to connect to the telephone line, separating voice and data communications using a splitter.

Asymmetric Digital Subscriber Line; a technology that transmits data over existing telephone lines, with higher downstream speeds than upstream.

Digital Subscriber Line Access Multiplexer; a device at the telephone company site that multiplexes multiple ADSL lines and packetizes the data for transmission to the internet.

High-bit-rate Digital Subscriber Line; an alternative to T-1 lines, offering higher data rates over longer distances without repeaters.

Symmetric Digital Subscriber Line; a one twisted-pair version of HDSL providing full-duplex symmetric communication.

Very high bit-rate Digital Subscriber Line; an alternative to ADSL, using coaxial, fiber-optic, or twisted pair for short distances, with DMT modulation.

Discrete Multitone Technique; a modulation technique used in ADSL and VDSL to transmit data over telephone lines.

A device used to separate voice and data signals on an ADSL line. Usually installed on the customer's premises.

A standard digital telecommunications line with a data rate of 1.544 Mbps, used for long distance communication.

Alternate Mark Inversion; a signaling method used to transmit data over a T-1 line that is susceptible to attenuation at high frequencies.

A signaling method that uses two binary data bits to create one four-level signal, less susceptible to high frequency attenuation for long distance data transmissions.

The ability to simultaneously transmit and receive data in both directions over a communication channel.

Upstream communication rates in XDSL range from 25 to 55 Mbps for distances between 3000 to 10,000 ft. Downstream speed is usually 3.2 Mbps.

XDSL supports both symmetric (same bandwidth in both directions) and asymmetric (bandwidth varies in different directions) configurations.

Asymmetric XDSL is suited for web browsing, while symmetric XDSL is good for video conferencing.

XDSL technology has various specifications, like DSL, HDSL, S-HDSL/SDSL, ADSL, RADSL, and VDSL, characterized by different rates and technologies.

High-bit-rate DSL, transmitting 2.048Mbps over two pairs up to 4.2 km.

Single-pair or symmetric high-bit-rate DSL, offering 768Kbps transmission on a single pair.

Asymmetric DSL offering data rates up to 6Mbps in one direction.

Rate-Adaptive DSL providing various data rates for local loop qualities.

Very High-bit-rate asymmetric DSL achieving speeds up to 52Mbps in one direction and 2Mbps in the other.

A device used to expand the range of an Ethernet network beyond typical limits, generally up to 100 meters.

Forwards traffic between Local Area Networks (LANs) over longer distances than standard Ethernet allows.

LAN extenders using unconditioned copper wiring, without load coils, in 2 or 4 wire variants.

Methods used by network extenders to transmit data, such as TC-PAM, 2B1Q, or DMT.

Full-duplex point-to-point link over voice-grade copper, supporting up to 2700 meters using G.991.2 (G.SHDSL.bis).

Full-duplex short-reach point-to-point link over voice-grade copper, supporting up to 750 meters using VDSL (G.993.1).

Enables connections between copper-based Ethernet equipment and fiber optic links, expanding distance and protecting data from interference.

Unshielded twisted pair (UTP) copper-based Ethernet connections are limited to approximately 100 meters.

Using fiber optic cabling to extend Ethernet connections beyond the limitations of copper cables.

Noise that can corrupt data transmission, especially with copper cables.