Wired Broadband and Related Industry
Glossary of Terms with Acronyms
As of 13 June 2011
Compiled By: Conrad L. Young, Director, Broadband Technical Strategy, RFMD
This document is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
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One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 1000 Mbps (baseband) carried over twisted pair. Also known as Gigabit Ethernet or GigE.
One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 100 Mbps (baseband) carried over twisted pair. Also known as Fast Ethernet.
One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 10 Mbps (baseband) carried over twisted pair.
A rectangular or “square” quadrature amplitude modulation (QAM) constellation with 256 symbols per quadrant. Refer to the Glossary subject “M-ary QAM” for more details.
One-One; a short-hand description for DOCSIS® 1.1.
IEEE 1394, also called Firewire.
16-Quadrature Amplitude Modulation (QAM) is a modulation technique employing both phase modulation (PM) and amplitude modulation (AM). Widely used to transmit digital signals such as digital cable TV and cable Internet service, QAM is also used as the modulation technique in orthogonal frequency division multiplexing (see OFDM). The "quadrature" comes from the fact that the phase modulation states are 90 degrees apart from each other. 16-QAM is a rectangular, or “square”, QAM constellation. Rectangular QAM constellations are, in general, sub-optimal in the sense that they do not maximally space the constellation points for a given energy. However, they have the considerable advantage that they may be easily transmitted as two pulse amplitude modulation (PAM) signals on quadrature carriers, and can be easily demodulated. The non-square constellations achieve marginally better bit-error rate (BER) but are harder to modulate and demodulate. The first rectangular QAM constellation usually encountered is 16-QAM, the constellation diagram for which is shown here:
Constellation diagram for rectangular 16-QAM.
A Gray coded bit-assignment is also given. The reason that 16-QAM is usually the first is that a brief consideration reveals that 2-QAM and 4-QAM are in fact binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK), respectively. Also, the error-rate performance of 8-QAM is close to that of 16-QAM (only about 0.5 dB better), but its data rate is only three-quarters that of 16-QAM.
Analog QAM uses two carriers 90 degrees out of phase with each other. Each carrier is modulated by an analog signal, and the resulting modulated waves are combined.
In digital QAM, the input stream is divided into groups of bits based on the number of modulation states used. For example, in 8QAM, each three bits of input, which provides eight values (0-7) alters the phase and amplitude of the carrier to derive eight unique modulation states (see example below). In 64QAM, each six bits generates 64 modulation states; in 128QAM, each seven bits generates 128 states, and so on. See modulation.
Short for 2 Binary, 1 Quaternary. 2B1Q is a full-duplex digital signaling technique used by many digital communications technologies (like ISDN) to send data over a single pair of wires. It uses a system of three different voltages: one for each of the two binary states (the 2B part of “2B1Q”) and a third, quaternary voltage that indicates both ends of the data connection are sending the same binary value.
Two-dimensional axes Micro-Electrical Mechanical Systems (MEMS) [IEC06]
2D MEMS Optical Switch
Micro-Electrical Mechanical Systems (MEMS) switch cores come in two designs: 2D MEMS, where the mirrors are arrayed on a single level (and therefore can be adjusted only in two dimensions), and 3D MEMS, where the mirrors are on multiple planes. Photonic switches use MEMS-based core materials to provide all-optical light switching. Tiny reflective components, resembling mirrors, are adjusted to steer an optical signal. [IEC06]
2D MEMS Optical Switch Diagram courtesy of International Engineering Consortium, http://www.iec.org/newsletter/jan06_2/broadband_1.html
The RCA 2N3866; a silicon bipolar junction transistor (BJT) introduced in the 1960s by Radio Corporation of America (RCA) for high gain (10 to 20 dB) VHF and UHF communications power amplifier and driver applications. The RCA 2N3866 was the first widely employed solid state (non vacuum tube based) amplifier device within the emerging US based cable television (CATV) industry for coaxial cable plant signal distribution and delivery over long distances. The RCA 2N3866 is a one (1) Watt RF power output capable amplifier with 10-dB rated gain at 400 MHz and 20-dB rated gain at 100 MHz. The following is an excerpt from the RCA 2N3866 datasheet listed in the RCA Solid State Division RF Power Devices Data Book 1974 [Dat11]:
The 2N3866 is an epitaxial silicon n-p-n planar transistor employing an advanced version of the RCA-developed "overlay" emitter-electrode design. This electrode consists of many isolated emitter sites connected together through the use of a diffused-grid structure and a metal overlay which is deposited on a silicon oxide insulating layer by means of a photo-etching technique. This overlay design provides a very high emitter periphery-to-emitter area ratio resulting in low output capacitance, high RF current handling capability, and substantially higher power gain. The 2N3866 is intended for class-A, -B, or -C amplifier, frequency-multiplier, or oscillator circuits: it may be used in output, driver, or pre-driver stages in vhf and uhf Equipment.
Photograph of RCA 2N3866 Transistor in TO-39 Package courtesy of GALCO Industrial Electronics, https://www.galco.com/scripts/cgiip.exe/wa/wcat/itemdtl.r?listtype=&pnum=2N3866-RCA