10Base2:   A form of Ethernet and IEEE 802.3 network cabling using thin coaxial. It refers to 10Mbit/s speed Baseband transmission of 200 meters maximum length and is commonly known as Cheapernet or ThinNet.

10Base5:   A form of Ethernet and IEEE 802.3 network cabling using thick coaxial. It refers to 10Mbit/s speed baseband transmission and 500 meters maximum length and is commonly known as ThickNet.

10Base-T:   A form of Ethernet and IEEE 802.3 network cabling using twisted pair cabling. It refers to 10Mbit/s speed Baseband transmission over twister pair cable CAT3, CAT4 or CAT5 with a maximum segment length of 100 meters.

100Base-T:   A form of Ethernet and IEEE 802.3 network cabling using twisted pair cabling. It refers to 100Mbit/s speed Baseband transmission over twister pair cable. 100Base-TX is over 2 pairs of Cat 5 UTP and 100 Base-FX is over fiber.

1000Base-T:   A form of Ethernet and IEEE 802.3 network cabling using twisted pair cabling. It refers to the 100BASE-T Ethernet network access method which operates at 1,000 Mbps or equivalently 1Gbps.

Attenuation:   The decrease in magnitude of a wave as it travels through any transmitting medium, such as a transformer or a filter. Attenuation is measured as a ratio or as the logarithm of a ration (Decibel dB).

AUI:   Auxiallary Unit interconnect, a standard using DB-15 plugs to connect Ethernet transceivers to controllers.

Autotransformer:   A transformer that has a single winding with a tap such that a step up or a step down voltage can be obtained. The autotransfomer with the tap at the center is commonly used in 100Mbps magnetic to provide the balance for the devices.

Bandwidth:   The range of frequencies a transmission line or channel can carry: the greater the bandwidth, the greater the information - carrying capacity of a channel. For a digital channel this is defined in bit/s. For an analog channel it is dependent on the type and method of modulation used to encode the data.

Category 3 cable (CAT3):   Standard for UTP voice grade cabling specified by the EIA/TIA 568 standard for use at speeds up to 10Mbit/s including 10BaseT ethernet.

Category 4 cable (CAT4):   Cabling standard specified by EIA/TIA 568 for use at speeds up to 20Mbit/s including 10Mbit/s Token Ring.

Category 5 cable (CAT5):   Cabling standard specified by EIA/TIA 568 for use at speeds up to 1000Mbit/s including FDDI (TP-PMD), 100BaseT and 1000BaseT.

Common Mode Choke:   Another term for a coupled inductor which is intended to filter or choke out common mode signals.

Crosstalk:   A type of interference caused by audio frequencies. Measured in dB.

CMRR (Common Mode Rejection Ratio):   A measure of the ability of a device to reduce common-mode noise.

CSMA/CD (Carrier Sense Multiple Access with Collision Detection:   The access method used by local area networking technologies such as Ethernet.

Cww:   The interwinding or coupling capacitance between primary and secondary of the transformer. This capacitance impacts the high frequency roll-off of the ransformer. The higher the capacitance is, the lower the cutoff frequency will become. The parameter will affect the common mode noise rejection as well.

DCR (DC Resistance):   The DC resistance of the winding.

Decibel (dB):   The standard unit for expressing relative power levels. Decibels indicate the ratio of power output to power input. dB = 10 log 10 (P1/P2)

EMI (Electromagnetic Interference):   Any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of the electronics/electrical equipment.

Ethernet:   The most widely LAN transmission network. Based on a bus network topology, it runs at a maximum 1000Mbit/s and adopts CSMA/CD techniques over conventional co-axial cable, thin wire co-axial cable an unshielded twisted pair cabling. A fiber-optic implementation has also been defined. Originally developed by Xerox, Intel, and Dec, and later standardized by the IEEE as the IEEE 802.3 standard. This has several implementations - 10Base5 for use over conventional co-axial cable, 10/100/1000BaseF for use over optic fiber, 10/100/100BaseT for use over Unshielded Twisted Pair (UTP) cabling.

Fast Ethernet:   Proposed 100Mbit/s technology for workstation LANs from the Fast Ethernet Alliance. It has been adopted by the IEEE as the basis for the 100BaseT Ethernet standard.

FCC (Federal Communications Commission):   US regulatory and approvals agency.

Filter:   May consist of inductors, capacitors and resistors. Its role is to provide signal conditioning ,wave shaping, pass wanted signal and reject unwanted signal.

HPNA (Home Phone Networking Alliance):   An association of industry-leading companies working together to promote the network technology that connects peripheral devices in the home using the existing telephone line.

IEEE (Institute of Electrical and Electronics Engineers):   A group of experts that establishes electrical specification standars for electrical devices.

IEEE 802.3:   The IEEE standardization of Ethernet. A physical layer defininition that includes specification for the physical cabling plus the method of transmitting data and controlling access to the cable. It uses the CSMA/CD access method on a bus topology LAN.

Isolation   The electrical separation between two circuits or circuit elements.

Isolation Voltage:   The maximum ac or dc specificed voltage that may be continuoulsy applied between isolated circuits.

Insertion Loss:   is a comparison of the load power available with the transformer/filter in the circuit to the load power with the transformer/filter not in the circuit.

Leakage Inductance (LL):   In a transformer or choke, the flux of the primary does not link to the secondary will generate the leakage flux. The greater this leakage flux, the greater the leakage inductance. The leakage inductance is the inductance measured at one winding with all other windings short circuited. It has an effect on the bandwidth of the transformer.

Local Area Network (LAN):   A data network intended to serve a campus area. It connects two or more computers in a workgroup, department or building so those computers can exchange data via cables or broadcast devices.

MAU (Media Access Unit):  An ethernet transceiver.

MDI (Medium Dependent Interface):  The mechanical and electrical interface between the trunk cable medium and the MAU.

MDIX (Medium Dependent Interface Cross-over):   The mechanical and electrical interface that enables like devices to connect, using different pin-outs, avoiding conflicts that occur when receiving and transmitting packets that use the same pin-out.

OCL (Open Cirucit Inductance):   Refer to the primary inductance, it impacts the low frequency roll off of the transformer.

Primary Winding:  The coil winding connected to the input power available.

PHY (Physical Layers Device):   Defines hardware interfaces and access methods. It can operate at a speed of 10/100/1000Mbps.

PCMCIA (Personal Computer Memory Card International Association):   This term refers to the small credit card sized cards that are used on a portable computer.

Return Loss:   Return loss is the ratio, expressed in decibels, of the the fractional amount of signal reflection caused by an impedance mismatch (eg: at the input to a transformer with respect to its source impedance).

RJ-45 (Registered Jack-45):   An eight-wire connector used commonly to connect computers onto a local area network, especially Ethernets.

RJ-11 (Registered Jack-11):   A four-wire connector used commonly to connect almost all phones, faxes and modems to the wall plug for telephone service.

Secondary Winding:   The coil winding supplying the load.

UTP (Unshielded Twisted Pair):   A cable that contains a pair of twisted pair wires with no shield. This is the type of wiring used in 10/100/1000Base-T.

VoIP (Voice of Internet Protocol):   A method of sending voice over an Internet Protocol such as TCP/IP.