Glossary of Technical Terms

AC
(Alternating Current) - This is electrical current that varies from zero to a maximum value in one direction, or polarity, and returns to zero. It then reverses its direction (polarity) and rises to a maximum value in the opposite direction, and then returns to zero to complete the cycle. This cycle is repeated continuously. The number of cycles per second is its frequency, measured in hertz (Hz).
AC-3
The 5.1-channel sound system specified in the Standard for Digital-HDTV. Also known as "Dolby Digital", AC-3 delivers CD-quality digital audio and provides five full-bandwidth channels for front left, front right, center, surround left and surround right speakers, plus an LFE (low frequency effect) subwoofer, for a total of 5.1 channels.
ADISP
(Average Unavailability) - Also known as Average Discrete Interfering Signal Probability (ADISP), calculates the average probability that a node will exceed configured thresholds over a user-specified time interval. The ADISP is useful as a "figure of merit" test for a node's overall performance.
Advance Spectrum Analyzer Mode
Advanced Spectrum Analyzer mode displays the amplitude of all carriers, beats and other RF sources in the user-selectable spectrum from 4.0 MHz to 1.0 GHz with a user selectable resolution bandwidth from 10.0 KHz to 3.0 MHz with a Zero Span Function. This allows you to perform a test for Ingress noise interference on the forward and return path.
AFC
(Automatic Frequency Control) - This is a circuit that automatically keeps an oscillator on frequency. When present on a TV set, the AFC control usually applies to the TV channel tuning section. It keeps the tuner locked to the channel selected.
AFT
(Automatic Fine Tuning) - This is a circuit that automatically keeps an oscillator on frequency. When present on a TV set, the AFT control usually applies to the TV channel tuning section. It keeps the tuner locked to the channel selected.
AM
(Amplitude Modulation) - The process of impressing information on a radio frequency signal by varying its amplitude. Generally amplitude modulation is used for the purpose of relaying messages by voices, television, facsimile or other modes.
Amplifier
A device that boosts the strength of an electronic signal. In a cable system, amplifiers are spaced at regular intervals throughout the system to keep signals picture-perfect regardless of how far subscribers live from the headend.
Analog
A form of voice, video and data transmission that employs a continual electrical signal. A prevalent technology that reproduces sound waves to send local telephone transmissions, computer data and video signals.
Analog Device
A device that operates with variables represented by continuously measured quantities such as voltages, resistances, rotations, and pressures.
Analog Signal
A signal that is solely dependent on magnitude to express the information content.
Analog-to-Digital
A device that converts a signal whose input is information in the analog form and whose output is the same information in digital form.
ATSC
(Advanced Television Systems Committee) - This is the government-appointed body in charge of defining the standards for new digital television systems.
AUTO Test Mode
Automatic Test mode on the 860 performs a sequence of operations specified by a user-defined macro. When enabled it will automatically run a set number of user-defined tests against user-defined pass/fail parameters. It can run immediately or you can specify an interval/count for POP tests.
Auto Test Results Mode
Automatic Test Results Mode on the 860 is used to recall stored results of an Auto Test data log saved in your meter.
Bandwidth
The data transfer rate of information sent over a network in a given amount of time. The larger the bandwidth, the more information that can be sent in that same period of time.
Baud Rate
This is the number of symbols per second transferred. A symbol may have more than two states, so it may represent more than one binary bit (a binary bit always represents exactly two states). Therefore the baud rate may not equal the bit rate, especially in the case of recent modems, which can have up to nine bits per symbol.
BER
(Bit Error Rate). The fraction of bits transmitted that are received incorrectly.
BER mode
BER Mode is used to test the ratio of corrupted bits versus total bits of data for a selected channel. It provides a measurement of long-term BER. Similar to the BER measurement in QAM mode, it graphically displays both corrected and uncorrected errors over time - you can set the time to 200, 400, or 600 seconds.
Bit Error Rate
(BER). The fraction of bits transmitted that are received incorrectly.
Bluetooth
Bluetooth is a standard technology for implementing Personal Area Networks; that is, close-range networks for connecting up personal devices. You may have used Bluetooth for tasks like transferring a photo from your friend's mobile phone to yours. Bluetooth is defined in IEEE standard 802.15.1.
Broadband
Data transmissions of voice, data and video signals over a single medium at high speed. A descriptive term for evolving digital technologies that provide consumers with integrated access to voice, high-speed data service, video-demand services, and interactive delivery services.
C/N
(Carrier-To-Noise Ratio) The square of the ratio of the root mean square (RMS) of the voltage of the digitally-modulated Radio Frequency (RF) carrier to the RMS of the continuous random noise voltage in the defined measurement bandwidth. (If not specified explicitly, the measurement bandwidth is the symbol rate of the digital modulation; for video it is 4 MHz.)
C/N Mode
Carrier to Noise mode on the 860 displays the ratio of the amplitude of the visual carrier and the noise within a single, selected channel.
Cable Modem Statistics mode
This mode is used to perform a quick view of the cable modems information. It displays a signal's Symbol Rate, Energy Level, and Modulation (64 or 256 QAM), Signal-to-Noise ratio, corrected and uncorrected errors, and the current frequency.
Cable Modem Termination System
(CMTS) Located at the cable television system headend or distribution hub, a CMTS provides complementary functionality to the cable modems to enable data connectivity to a wide-area network.
Cable Network
Group of radio or television outlets linked by cable or microwave that transmit identical programs simultaneously, or the company that produces programs for them. Cable networks include companies such as: The Discovery Channel, ESPN, C-SPAN. National broadcast commercial television networks in the U.S. include ABC, NBC, CBS.
Cable System
Communications and entertainment system that distributes television, data, and telephone services by means of coaxial cables and/or fiber optics.
Cache
Local or temporary storage.
Carrier-to-Noise Ratio
(C/N or CNR) The square of the ratio of the root mean square (RMS) of the voltage of the digitally-modulated Radio Frequency (RF) carrier to the RMS of the continuous random noise voltage in the defined measurement bandwidth. (If not specified explicitly, the measurement bandwidth is the symbol rate of the digital modulation; for video it is 4 MHz.)
CATV
(Cable TV) - A transmission system that distributes broadcast television signals and other services by means of a coaxial cable.
CC
(Closed Captioned) - Visual captioning on television screen for the hearing impaired sent through the vertical blanking interval (line 21).
CCTV
(Closed Circuit Television) - Usually a security system using cameras that transmits visual information over a closed circuit through electrically conducting cable or wireless transmitter and receiver.
Channel
In television, a single path or section of the spectrum 6 MHz wide, that carries a television signal.
Clipping
The shearing off of the peaks of a signal. For a picture signal, this may affect either the positive (white) or negative (black) peaks. For a composite video signal, the sync signal may be affected. For Voice Loss of speech signal components in utterances.
CM Stat
Cable Modem Statistics mode is used to perform a quick view of the cable modems information. It displays a signal's Symbol Rate, Energy Level, and Modulation (64 or 256 QAM), Signal-to-Noise ratio, corrected and uncorrected errors, and the current frequency.
CM Thru mode
CM Thru provides a method of using the internal cable modem as a desktop modem by allowing a customer’s PC to connect to the External RJ-45 port and gain Internet access through the internal cable modem. Cable Modem to RJ-45 Port provides your downstream and upstream statistics. It operates just like CM Stat except that both the RF and the RJ-45 ports are active, so you can use the meter as a cable modem and access the Internet with any network-compatible device.
CMTS
(Cable Modem Termination System) Located at the cable television system headend or distribution hub, a CMTS provides complementary functionality to the cable modems to enable data connectivity to a wide-area network.
Coaxial Cable
A type of cable that can carry large amounts of bandwidth over long distances. Cable TV and cable modem service both utilize this technology. Coaxial Cable (COAX) - Copper or copper-sheathed aluminum wire surrounded by an insulating layer of polyethylene foam, used by CATV systems. The insulting layer is covered with tubular shielding composed of tiny strands of braided copper wire, or a seamless aluminum sheath, and protective outer skin. The wire and the shielding react with each other to set up an electromagnetic field between them. This system reduces frequency loss and gives cable its great signal-carrying capacity.
Common Path Distortion
(CPD) The interference of return path signaling caused by the forward path.
Composite Second Order Beat
(CSO) The peak of the average level of distortion products due to second-order non- linearies in cable system equipment.
Composite Triple Beat
(CTB) The peak of the average level of distortion components due to third-order non- linearies in cable system equipment.
CPD
(Common Path Distortion) The interference of return path signaling caused by the forward path.
Cross Modulation
A form of television signal distortion where modulation from one or more television channels is imposed on another channel or channels.
CSO
(Composite Second Order Beat) The peak of the average level of distortion products due to second-order non- linearies in cable system equipment.
CSO/CTB Mode
Composite Second Order / Composite Triple Beat mode on the 860 measures the amplitude of two common intermodulation products, Composite Second Order and Composite Triple Beat present within a selected analog video channel. It measures the noise or a distortion product underneath a carrier (when the modulator is switched off).
CTB
(Composite Triple Beat) The peak of the average level of distortion components due to third-order non- linearies in cable system equipment.
DA
(Digital-to-Analog Converter) This is an electronic device that is used to convert digital audio signals into analog audio signals, or more generally to convert digital signals into analog signals.
DAB
(Digital Audio Broadcast) This is the standard for digital radio in Europe, described in the "Eureka 147" standard, ETS 300 401, available from ETSI. DAB will eventually replace FM signals in the UK, and currently carries both audio programs (compressed in MP2 format) and data subchannels for use by various DAB-aware applications. Each DAB channel (in Eureka 147 terms, "Ensemble") contains a number of sub-channels, each typically containing a radio program service.
DARS
(Digital Audio Radio Service) This is the FCC term for satellite radio. It operates in the 2.3-GHz S band, from 2320 to 2345 MHz. Terrestrial repeaters retransmit the signals in areas that are prone to weak signals, due to overhead obstructions like tall buildings in downtown areas.
dB
(decibel) This is a unit of measure of signal strength, usually the relation between a transmitted signal and a standard signal source. Every 3 dB = 50% of signal strength, so therefore a 6 dB loss = a loss of 75% of total signal strength.
DC
(Direct Current) An electrical current which flows only in one direction in a circuit.
Decibel
(dB) A unit to measure the relative levels of current, voltage or power. An increase of 3 dB indicates a doubling of power, an increase of 10 dB indicates a 10x increase in power, and an increase of 20 dB indicates a 100x increase in power.
Demodulation
The extraction of the modulation or information from a radio-frequency current. Differential Gain In color TV, the change in gain, expressed in dB, for the 3.58-MHz color sub- carrier as the level of the luminance signal is varied from blanking to white. Differential Phase Variation in phase of the color sub-carrier of a TV signal as the level of the luminance signal is varied from blanking to white.
Depth of Modulation Mode
Depth of Modulation mode on the 860 displays the percentage of video modulation for the visual carrier of a single, selected channel. It is a headend test – not a field test. It is measured from the back of a modulator in the headend.
Digital
A telecommunications signal that transports voice, video and data elements using bits of information instead of sound waves.
Digital transmission
A technological process in which information is converted to digital form and then transmitted over a network in a stream of pulses.
Digital TV
The process of delivering television signals using the binary, or "digital," system of breaking those signals into tiny bits. Digital TV offers sharper pictures and sound than standard analog TV.
Distribution Hub
A location in a cable television network which performs the functions of a headend for customers in its immediate area, and which receives some or all of its television program material from a master headend in the same metropolitan or regional area.
Distribution Plant
The hardware of a cable system—amplifiers, trunk cable and feeder lines, attached to utility poles or fed through underground conduits like telephone and electric wires.
Distribution System
The part of a cable television system used to carry signals from the headend to subscriber's receivers. Often applied, more narrowly, to the part of a cable television system starting at the bridger amplifiers.
DNS
(Domain Name Server) A server that relates an Internet domain name (such as www.cablelabs.com) to an IP address.
DOCSIS®
(Data Over Cable Systems Interface Specifications) A cable TV industry standard set by CableLabs for cable modems. That standard ensures that certified modems can be used by all U.S. cable systems that market broadband connections. Domain name: The name of an Internet site. The top-level domains used in the U.S. are .com, .edu, .net, .gov, .int, .mil and .org.
DOCSIS® 1.0
The first version of the Data Over Cable Service Interface Specification. DOCSIS 1.0 defines requirements for cable modems and cable modem termination systems that enable broadband Internet access.
DOCSIS® 2.0
The third version of the DOCSIS protocol specification, developed to significantly increase the upstream data carrying capacity and the robustness to noise and interference. DOCSIS 2.0 includes advanced TDMA and S-CDMA physical layer technologies.
Domain Name Server
(DNS) A server that relates an Internet domain name (such as www.cablelabs.com) to an IP address.
Downstream
Flow of signals from the cable system control center through the distribution network to the customer. For communication purposes, associated with transmission (down) to the end-user. Or in cable television, the direction of transmission from the headend to the subscriber.
Drop
The cable and hardware from tap to subscriber is called the drop. Drop Cable is generally referred to as 330 feet or less, of coaxial cable, starting at a tap and continuing on to the subscriber’s connection. Or coaxial cable that connects to a residence or service location from a directional coupler (tap) on the nearest coaxial feeder cable.
DSP
(Digital Signal Processing) A specialized digital microprocessor used to efficiently and rapidly perform calculations on digitized signals that were originally analog in form (eg voice). The big advantage of DSP lies in the programmability of the processor, allowing parameters to be easily changed.
DTV
(Digital TV) The umbrella term used for the new broadcasting system adopted by the FCC in 1996. DTV includes all elements of digital broadcasting, including High and Standard Definition television, datacasting and multicasting. Analog television receives one continuous electronic signal. In contrast, DTV works on the same principle as a computer or a digitally recorded compact disk. It uses binary code, a series of ones and zeros, rather than a continuous signal.
DVR
(Digital Video Recorder) This is a high capacity hard drive that is embedded in a set-top box, which records video programming from a television set. These DVRs are operated by personal video recording software, which enables the viewer to pause, fast forward, and manage all sorts of other functions and special applications.
Dynamic IP address
An address that is assigned to a computer every time it connects to the Internet. Unlike a static IP address that will be the same every time the user logs on, a dynamic IP address is different every time.
Dynamic Range
The ratio between the greatest signal power that can be transmitted over a multichannel analog transmission system without exceeding distortion or other performance limits, and the least signal power that can be utilized without exceeding noise, error rate or other performance limits.
E-Model
This is used to predict the subjective effect of combinations of impairments using stored information on the effects of individual impairments. The basic principal of the model is that "Psychological factors on the psychological scale are additive". The model works in transmission ratings (R-Factor) which are related to the Mean Opinion Score (MOS). The basic equation for the model is: R = Ro - Is - Id - Ie + A. Where Ro = S/N at 0 dBr point, Is = Impairments simultaneous to voice signal, Id = Impairments delayed after voice signal, Ie = Effects of special equipment (e.g. codecs), and A = Advantage factor (to take account of user advantages such as mobility).
EBS
(Emergency Broadcast System) Used to inform the public about an emergency and the protective actions to take. The EBS is a service of local radio and television stations, activated as needed and approved by a local emergency management agency.
Echo
A wave which has been reflected at one or more points in the transmission medium, with sufficient magnitude and time difference to be perceived in some manner as a wave distinct from that of the main or primary transmission. Echoes may be either leading or lagging the primary wave and appear on the picture monitor as reflections or “ghosts.” Also known as reflection. This is the effect you experience over a phone call when you hear your own voice back after some milliseconds. The amount of time after which you hear the echo varies depending on the factors that are causing the echo. An echo of a few milliseconds is bearable; you only feel as if you are speaking in an empty room. An echo of a few hundred milliseconds can be extremely annoying and can affect the call completely. For echo to be noticeable, it has to be loud and delayed. Delay already exists in PSTN networks, but it is more noticeable in VoIP because the latter has more delay. PSTN network phone calls function with a delay of no more than 10 milliseconds; while VoIP phone calls can have up to a 400 milliseconds delay.
EHF
(Extremely High Frequency) These are frequencies between 30,000 and 300,000 megacycles per second electromagnetic spectrum. A collective term for all known radiation, from the shortest-waved gamma rays through x-rays, ultraviolet, visible light, and infrared waves, to radio waves at the long-waved end of the spectrum.
EL
(Electroluminescence) This is an optical phenomenon and electrical phenomenon where a material emits light in response to an electric current passed through it, or to a strong electric field. This is distinct to light emission resulting from heat (incandescence) or from the action of chemicals (chemoluminescence).
Emergency Alert System
(EAS) The US federal system for alerting the public to emergencies. EAS is a digital upgrade to the old Emergency Broadcasting System.
EMTA
(Embedded Multimedia Terminal Adapter) - The same device as an MTA, connects the subscriber equipment (telephone and computer) to the network. Includes a cable modem, and is available in indoor and outdoor configurations.
ERP
(Effective Radiated Power) In radio telecommunications, this is determined by subtracting system losses from system gains. ERP is typically applied to antenna systems. For example, if an antenna system has +9 dB gain and −6 dB loss, its ERP is +3 dB over the transmitter power output (TPO).
Ethernet
An international standard that networks computers and transmits data over copper wires at a speed of 10 mbps.
FCC
(Federal Communications Commission) A Federal regulatory agency that is responsible, among other things, of regulating VoIP.
FEC
(Forward Error Correction) This is a communications technique that is used to correct errored data on the receiving end. Before transmission, the outgoing data is processed through an algorithm that adds extra bits that are used for error correction. If the transmitted message is received in error, the correction bits are used to repair it.
File Menu
The File Menu allows you to perform file maintenance functions such as previewing and deleting files. Explore Files, display all of the files stored in your meter. You can preview graphic files on this display, or open text files.
FiOS
FiOS is a fiber to the premises (FTTP) telecommunications service offered in the United States by Verizon. Verizon states that it stands for "fiber-optic service."
Firewall
A set of programs in a server that protect information in a private network from outside users.
Firmware Version
This is the ID number of the software which is installed in an 860 DSP or DSPi. This can be found on the instrument by going to the INSTRUMENT INFORMATION Mode and highlighting the Version Info Field.
FM DEV Mode
FM Deviation Mode on the 860 displays the current and maximum FM deviation on the audio carrier of a single, selected channel. This Menu allows you to “listen” to a channel to test for audio problems or to identify whether a cable is carrying a television signal (so if there are multiple coax cables in a house, you can identify the one that carries the CATV signal).
Frequency
The number of times an electromagnetic signal repeats an identical cycle in a unit of time, usually one second. One Hertz (Hz) is one cycle per second; a KHz (Kilohertz) is 1,000 cycles per second; a MHz (Megahertz) is 1 million cycles per second; and a GHz (Gigahertz) is 1 billion cycles per second. Frequency also can refer to the portion of the electromagnetic spectrum, or channel, in which a device, such as a radio, television or telephone, operates.
FTP
(File Transfer Protocol) is used to transfer data from one computer to another over the Internet, or through a network. Specifically, FTP is a commonly used protocol for exchanging files over any network that supports the TCP/IP protocol (such as the Internet or an intranet).
FTTH
(fiber to the home) is a form of fiber optic communication delivery in which the optical signal reaches the end user's living or office space.
FTTN
(Fiber to the node) is a broadband architecture that provides high speed internet and other services to the home by running fiber to the node and some form of DSL to the end-user.
FTTP
(fiber to the building, also called fiber premise or to the basement) is a form of fiber optic communication delivery in which the optical signal reaches the premises but stops short of the end user's living or office space.
FTTX
Fiber to the x is a generic term for any network architecture that uses optical fiber to replace all or part of the usual copper loop used for telecommunications.
G.711 Codec
This is the default pulse code modulation (PCM) standard for Internet Protocol (IP) private branch exchange (PBX) vendors, as well as for the public switched telephone network (PSTN). G.711 digitizes analog voice signals producing output at 64 kilobits per second (Kbps).
Gain
A measure of amplification expressed in dB. Gain of an amplifier is usually specified at the highest frequency of operation, for example, at Channel 13 of all- band equipment.
gbps
(gigabits per second) A measurement of speed for digital signal transmission that's expressed in billions of bits per second.
GHz
(GigaHertz) One billion cycles of electrical frequency per second.
GPS
(Global Positioning System) A system using satellite technology that allows an equipped user to know exactly where he is anywhere on earth.
Headend
The control center of a cable television system, where incoming signals are amplified, converted, processed and combined into a common cable along with any original cablecasting, for transmission to subscribers. The system usually includes antennas, preamplifiers, frequency converters, demodulators, modulators, processors and other related equipment. Or the central location on the cable network that is responsible for injecting broadcast video and other signals in the downstream direction.
HFC
(Hybrid Fiber Coaxial Network) An outside plant distribution cabling concept employing both fiber optic and coaxial cable.
High Speed Internet / High Speed Data
High-speed Internet access or “broadband” allows users to access the Internet and Internet-related services at significantly higher speeds than those available through “dial-up” Internet access services. The Federal Communications Commission (FCC) generally defines broadband service as data transmission speeds exceeding 200 kilobits per second (Kbps), or 200,000 bits per second, in at least one direction: downstream (from the Internet to your computer) or upstream (from your computer to the Internet).
HTTP
(Hyper Text Transfer Protocol) This protocol is used by the World Wide Web. HTTP defines how messages are formatted, transmitted, and what servers and browsers should do in response to user commands. When entering a URL into a Web browser, the Web browser sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page.
Hub
A networking device that lets all of the devices attached to it, such as personal computers, to receive the information transmitted over the network and to share network bandwidth.
Hum Mode
Hum mode on the 860 displays the amplitude of the 50/60 Hz, 100/120 Hz and low frequency interference present on the video carrier of a single selected channel. This helps you identify passive (cable issues, grounding) and active (power supply, amp issues) problems with the installation.
Hz
(Hertz) A unit of frequency equal to one cycle per second.
IL
(Insertion Loss) Additional loss in a system when a device such as a directional coupler is inserted; equal to the difference in signal level between input and output of such a device.
Info Screen
The Info Screen on the 860 provides information about the 860’s operation capabilities. It Provides a configuration summary that will help Trilithic technicians troubleshoot any questions or problems you have with your meter.
Insertion Loss
(IL) Additional loss in a system when a device such as a directional coupler is inserted; equal to the difference in signal level between input and output of such a device.
IP address
(Internet Protocol address) A numeric notation that represents a unique address for any network device on the Internet; an Internet address expressed in numbers.
ISDN
(Integrated Services Digital Network) It offers digital transmission of information through the Internet, as opposed to transmitting it over the telephone.
ISP
(Internet Service Provider) A company providing Internet access to consumers and businesses, acting as a bridge between customer (end-user) and infrastructure owners for dial-up, cable modem and DSL services.
Jitter
The variance in latency. Or variability in the delay of a stream of incoming packets making up a flow such as a voice communication.
Kbps
(Kilobits per second) 1,000 bits per second. A measure of how fast data can be transmitted.
KS Port
This is the port on a tap that is unscrewed to access the seizure screw. This port is typically used to install an I-Stop Probe at the tap.
LAN
(Local Area Network) A geographically localized network consisting of both hardware and software. The network can link workstations within a building or multiple computers with a single wireless Internet connection.
Last mile
The final leg of a cable TV, telephone or other telecommunications network that ends in the user's household. The last mile can be a copper wire, fiber-optic line or a wireless link.
Latency
This is the delay it takes for a packet of data to get from one designated point to another. This represents the delay that increases real or perceived response time beyond the desired response time .
Level Mode
Level mode on the 860 displays the amplitude of the carriers included in a single channel, or the amplitude of a signal at a selected frequency.
LPR
(Lost Packet Rate) This is the number of data packets are lost over a set period of time.
LPR%
(Lost Packet Rate %) This is the percentage of lost packets to received packets over a set period of time.
MAC-Address
(Media Access Control Address or Medium Access Control) The unique hardware number assigned to network connection devices such as your computer's network card. In Ethernet, it is written as a series of six pairs of characters divided by hyphens (e.g., 00-0F-3D-50-A1-98), and is also referred to as the hardware address or adapter address. Or the “built-in” hardware address of a device connected to a shared medium.
Mbps
(Megabits per second) 1,000,000 bits per second. A measure of how fast data can be transmitted.
Mean Time to Repair
(MTTR) In cable television systems, the MTTR is the average elapsed time from the moment a loss of radio frequency (RF) channel operation is detected up to the moment the RF channel operation is fully restored.
MER
(Modulation Error Ratio) This is a measure of the signal-to-noise ratio (SNR) in a digitally modulated signal. Like SNR, MER is usually expressed in dB.
MIB
(Management Information Base) An SNMP-defined data structure used for storing and retrieving information to and from network elements.
Mod Mode
Depth of Modulation mode on the 860 displays the percentage of video modulation for the visual carrier of a single, selected channel. It is a headend test – not a field test. It is measured from the back of a modulator in the headend.
Modulation
When some characteristics of an electromagnetic wave are deliberately changed or manipulated for the purpose of transmitting information. Process by which signals are transformed to represent information (or data). Generally uses different frequencies to transmit data (FM). See also QAM.
MOS
(Mean Opinion Score) Rating used to evaluate the perceived voice quality of a call consisting of an arithmetic average of a set of opinion scores representing subjective assessments of voice quality.
MSO
(Multiple System Operator) A company that owns two or more cable TV systems.
MTA
(Multimedia Terminal Adapter) - The device in a PacketCable network that connects the subscriber equipment (such as telephone) to the network. Configured as either indoor or outdoor units.
MTTR
(Mean Time to Repair) In cable television systems, the MTTR is the average elapsed time from the moment a loss of radio frequency (RF) channel operation is detected up to the moment the RF channel operation is fully restored.
Network Element
Hardware within a communications network that provides telephone services.
Node
(1) An addressable unit in a network, which can be a computer, workstation or some type of communications control unit. (2) Point in a cable television system that interconnects traditional coaxial cable and fiber-optics. The place where an optical signal is converted to a radio frequency (RF) signal, or vice versa.
Packet
A unit of information transmitted as a whole from one device to another on a network.
Packet switching
A network-transmission process that splices data into small, destination-coded units, or "packets," that are then sent through the network. At their destination, all of the packets are reassembled into a whole package, which can be an e-mail, voice transmission or video element.
PESQ
(perceptual evaluation of speech quality) Algorithm used to derive opinion scores on the perceived voice quality of a call, based on a psychoacoustic model that compares original, unprocessed signals with degraded signals from the network.
Phase Distortion
When the output of an amplifier fluctuates in phase, even though the input does not, the circuit introduces phase distortion into the signal.
PING
A method of bouncing a signal to a computer's IP address to check if it is online and to measure the response time. Rather like radar or echo location.
PING mode
Provides the ability to PING the network connection to check network connectivity between network devices. You can ping by a domain name like www.yahoo.com or by a specific IP address.
Post BER
(Bit Error Rate) The fraction of bits transmitted that are received incorrectly after correction.
POTS Network
(Plain Old Telephone Service) This refers to the standard telephone service that most homes use, telephone services based on high speed digital communication lines, such as ISDN and FDDI are not POTS. The distinction between POTS and non-POTS services is speed and bandwidth. POTS is generally restricted to about 52 Kbps.
Power Menu
The Power Menu on the 860 allows you to change power management settings for Power Scheme, Processor Speed, Backlight Level, Unit Off Timer and BackLight Timer.
Pre BER
(Bit Error Rate) The fraction of bits transmitted that are received incorrectly before correction.
Provisioning
The process of preparing a telephone, cable TV or other network line so it can support a broadband-access connection, such as a cable modem or DSL link.
PSTN
(Publish Switched Telephone Network) This is the international telephone system based on copper wires carrying analog voice data. This is in contrast to newer telephone networks based on digital technologies, such as ISDN and FDDI.
QAM
(Quadrature Amplitude Modulation) A method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding. A modulation scheme used by telecommunications providers. More advanced modulation offers increased capacity (e.g., 256 QAM offers greater capacity/transmission speeds than 64 QAM).
Swoosh