|4-Port Optical Node
A device employed within hybrid fiber coaxial (HFC) networks that converts downstream optical wavelength signals from a cable operator headend (HE) or hub to low noise RF, amplifies and splits these downstream RF signals into four (4) distinct RF outputs with a combination of high RF power output and low distortion. The device RF ports are diplex filtered to permit simultaneous transmission of downstream RF signals and reception of upstream RF signals. Upstream RF signals are combined within the device, converted from RF to optical wavelength by a laser and transmitted via optical fiber from the device to a cable operator HE or hub.
Excerpt from ANSI/SCTE 87-1 2008,
“Graphic Symbols For Cable Systems Part 1: HFC Symbols”
5/8-24 RF & AC Equipment Port, Female
Equipment ports of this type are defined by ANSI/SCTE 91 2009, Specification for 5/8-24 RF & AC Equipment Port, Female. This specification serves as a recommended guideline for the physical dimensions of all female 5/8 – 24 equipment ports for RF and AC powering that are used in the 75 ohm RF broadband communications industry.
5/8-24 Plug, Male Adapters
Also referred to as a “Stinger”. Coaxial cable connector employed to connect hybrid fiber coaxial (HFC) network transmission line optical nodes, trunk/bridger, and line extender (LE) amplifiers to low loss, large diameter coaxial cable. Male connectors of this type are defined by ANSI/SCTE 111 2010 Specification for 5/8-24 Plug, Male Adapters. This specification serves as a recommended guideline for the physical dimensions of 5/8 – 24 plug (male) hard-line adapters that are used as interconnects in the 75 ohm RF broadband communications industry. It is not the purpose of this standard to specify the details of manufacturing. This type of termination is also known as a “trunk and distribution” coaxial cable connector.
More appropriately called Pulse Code Modulation (PCM) Modems, these modems manipulate the way the telephone system works to send data to an analog “modem” type device at speeds of up to 56,000 bits per second (56Kbps). 56K modems work by using ISDN telephone equipment at one end of the connection to manipulate the PCM codes sent across the telephone network. When these PCM sample codes reach the Codec they are translated into a specific series of voltage changes that a PCM modem knows how to interpret. Data sent out by a 56Kbps modem is subject to the same physical restrictions of any modem, so its top “back channel” speed is 33.6Kbps. 56Kbps modems are built against the ITU-T V.90 or V.92 standards.
5 Companies that license Digital Transmission Content Protection (DTCP); Sony, Matsushita (Panasonic), Intel, Toshiba, Hitachi. Refers to the five founding companies of the Digital Transmission Content Protection (DTCP) technology. Sony, Matsushita, Intel, Toshiba and Hitachi. Also used to refer to 5C digital certificates.
A telephone company central office switch manufactured by Lucent Technology (an AT&T spin-off company) which has ISDN and other digital telephony capabilities. Frequently abbreviated to 5E. See also DMS-100.
60 Cycle Hum
These hum bars at 60 cycles are normally a result of dc power on the line. See DC Blocker. [Cha07]
A rectangular or “square” quadrature amplitude modulation (QAM) constellation with 16384 symbols per quadrant. This form of QAM is more accurately referred to as 65536-QAM. Refer to the Glossary subject “M-ary QAM” for more details.
8-Quadrature Amplitude Modulation (QAM) is a modulation technique employing both phase modulation (PM) and amplitude modulation (AM).
IEEE Working Group for High Level Interfaces, Network Management, Inter-networking, and other issues common across LAN technologies. [Tim11]
IEEE Working Group for Carrier Sense Multiple Access/Carrier Detect Local Area Networks. [Tim11]
8-level Vestigial Sideband; a standard radio frequency (RF) modulation format chosen by the Advanced Television Systems Committee (ATSC) for the transmission of digital television (DTV) to consumers in the United States and other adopting countries. In the US, the standard is specified by the Federal Communications Commission (FCC) for all digital television broadcasting. Countries in Europe and elsewhere have adopted an alternative format called Coded Orthogonal Frequency Division Multiplexing (COFDM). The main ATSC standards for DTV are 8-VSB, which is used in the transmission of video data, MPEG-2 for video signal compression, and Dolby Digital for audio coding. The 8-VSB mode includes eight amplitude levels (23) that support up to 19.28 Mbps of data in a single 6 MHz channel. There is also a 16-VSB mode that has 16 amplitude levels and supports up to 38.57 Mbps of data on a 6 MHz channel. 8-VSB is considered effective for the simultaneous transmission of more than one DTV program (multicasting) and the transmission of data along with a television program (datacasting) because it supports large data payloads.
The ATSC adopted the VSB transmission system because of its large bandwidth, which is needed to transmit HDTV (high definition television) programming. Detractors claim that this larger bandwidth is irrelevant if customers cannot view the transmitted program because of multipath effects. When a signal is transmitted, it is met with obstructions such as canyons, buildings, and even people, which scatter the signal, causing it to take two or more paths to reach its final destination, the television set. The late arrival of the scattered portions of the signal causes ghost images. For this reason, some consumers in metropolitan areas or areas with rugged terrain opt for cable television instead of fighting their antennas for better reception. Because a VSB signal is transmitted on one carrier, it scatters like water blasted on a wall when met with obstacles, which is not a problem with COFDM, the European standard modulation technique, because it transmits a signal on multiple carriers.
VSB advocates state that simply buying an outdoor antenna that rotates solves the multipath interference problem, but critics worry that customers do not want to buy an expensive rotating outdoor antenna to view free television programs. They also worry that the poor reception and the added expense of an outdoor antenna are slowing the transition to DTV in ATSC-compliant countries. The VSB scheme also does not support mobile television viewing. VSB equipment manufacturers are working on solutions to these two problems. [Wha10]
16-level vestigial sideband modulation, capable of transmitting four bits (24=16) at a time. Other slower but more rugged forms of VSB include 2VSB, 4VSB, and 8VSB. 16VSB is capable of twice the data capacity of 8VSB; while 8VSB delivers 19.34 Mbit/s (Megabits per second) in a 6 MHz TV Channel, 16VSB could deliver 38.68 Mbit/s, while making the sacrifice of being more prone to transmission error. While 8VSB is the FCC ATSC (USA/Canada) digital broadcast modulation format, 16VSB was planned for cable distribution. 16VSB is about twice as susceptible to noise as 8VSB, therefore less suitable for over-the-air (OTA) broadcast, but well suited to the SNR of fiber/cable distribution, allowing twice as much programming in a 6MHz band channel. The US cable industry opted not to carry any form of VSB modulation, but instead carries OTA broadcast television DTV programming via 256QAM, the standard downstream (DS) modulation method for digital cable in the US. [Wor11]
Authentication, Authorization, and Accounting. AAA is a suite of network security services that provide the primary framework through which access control can be set up on your Cisco router or access server. [Cis00]
A high isolation switch used to select between two input signal sources.[Arr11]
Available Bit Rate; an ATM layer service where the limiting ATM-layer transfer characteristics provided by the network may change subsequent to the connection established.
The process by which electromagnetic radiation (EMR) is assimilated and converted into other forms of energy, primarily heat. Absorption takes place only on the EMR that enters a medium, and not on EMR incident on the medium but reflected at its surface. A substance that absorbs EMR may also be a medium of refraction, diffraction, or scattering; however, these processes involve no energy retention or transformation and are distinct from absorption. [Tim11]
A range of wavelengths (or frequencies) of electromagnetic radiation that is assimilated by a substance. [Tim11]
A measure of the attenuation caused by absorption of energy that results from its passage through a medium. Note 1: Absorption coefficients are usually expressed in units of reciprocal distance. Note 2: The sum of the absorption coefficient and the scattering coefficient is the attenuation coefficient. [ATI11]
A mechanism to group a set of related unbound applications where some aggregator has taken the responsibility to ensure that the set of related applications work together. This is a generalization of a broadcast service to support applications not related to any broadcast TV service. A set of resident applications which an MSO has packaged together (e.g., chat, e-mail, WWW browser) could comprise one abstract service.
Abstract Windowing Toolkit (AWT)
A Java package that supports Graphical User Interface (GUI) programming.
Audio Coding Standard developed by Dolby Labs.
AC Hum Modulation
See hum modulation.
Acceptance Test Plan (ATP)
A compendium of test procedures that may be used to demonstrate compliance with certain specifications.
Channels set aside by the cable operator for use by the public, educational institutions, municipal government, or for lease on a non-discriminatory basis.
Limiting the flow of information from the resources of a system only to authorized persons, programs, processes, or other system resources on a network.
The part of the carrier network that touches the customer's premises. The Access Network is also referred to as the local drop, local loop, or last mile.
Access Node (AN)
Part of the Access Network which performs some or all of the following: modulating forward data onto the Access Network; demodulating return-path data; enforcing the Media Access Control (MAC) protocol for access onto the Access Network; separating or classifying traffic prior to multiplexing onto the Transport Network— such as differentiating traffic that is subject to Quos guarantees from traffic that receives best-effort support; enforcing signaling; handling passive operations such as splitting and filtering.
Additional Call Offering
Acousto-Optic Modulator (AOM)
A device which can be used for controlling the power, frequency or spatial direction of a laser beam with an electrical drive signal. It is based on the acousto-optic effect, i.e. the modification of the refractive index by the oscillating mechanical pressure of a sound wave.
The key element of an AOM is a transparent crystal (or piece of glass) through which the light propagates. A piezoelectric transducer attached to the crystal is used to excite a sound wave with a frequency of the order of 100 MHz. Light can then experience Bragg diffraction at the traveling periodic refractive index grating generated by the sound wave; therefore, AOMs are sometimes called Bragg cells. The scattered beam has a slightly modified optical frequency (increased or decreased by the frequency of the sound wave) and a slightly different direction. (The change in direction is smaller than shown in Figure below, because the wavenumber of the sound wave is very small compared with that of the light beam.) The frequency and direction of the scattered beam can be controlled via the frequency of the sound wave, whereas the acoustic power is the control for the optical powers. For sufficiently high acoustic power, more than 50% of the optical power can be diffracted – in extreme cases, even more than 95%.
Schematic setup of a non-resonant acousto-optic modulator
A transducer generates a sound wave, at which a light beam is partially diffracted. The diffraction angle is exaggerated. The acoustic wave may be absorbed at the other end of the crystal. Such a traveling-wave geometry makes it possible to achieve a broad modulation bandwidth of many megahertz. Other devices are resonant for the sound wave, exploiting the strong reflection of the acoustic wave at the other end of the crystal. The resonant enhancement can greatly increase the modulation strength (or decrease the required acoustic power), but reduces the modulation bandwidth. Common materials for acousto-optic devices are tellurium dioxide (TeO2), crystalline quartz, and fused silica. There are manifold criteria for the choice of the material, including the elasto-optic coefficients, the transparency range, the optical damage threshold, and required size. One may also use different kinds of acoustic waves. Most common is the use of longitudinal (compression) waves. These lead to the highest diffraction efficiencies, which however depend on the polarization of the optical beam. Polarization-independent operation is obtained when using acoustic shear waves (with the acoustic movement in the direction of the laser beam), which however make the diffraction less efficient. There are also integrated-optical devices containing one or more acousto-optic modulators on a chip. This is possible, e.g., with integrated optics on lithium niobate (LiNbO3), as this material is piezoelectric, so that a surface-acoustic wave can be generated via metallic electrodes on the chip surface. Such devices can be used in many ways, e.g. as tunable optical filters or optical switches.