| 66-type
Punch-Down Block |
 |
|
A block consisting of four columns of 50 pins each,
onto which the 50 wires of the 25-pair group are placed.
Each wire is placed in a pin, and then punched into
place, stripping the insulation in the process. The
pins in columns 1 and 2 are shorted together, and the
pins in columns 3 and 4 are shorted together. This creates
an input and output side of the block. To connect the
two halves, bridging or shorting clips are used between
pins 2 and 3 of any particular row. The 66-Type Punch-Down
Block provides easy access to each wire and is used
to terminate most twisted-pair cable. Most installed
66-Type Blocks do not support Category 5.
|
| |
| 802.3 |
|
| The Institute of
Electrical and Electronic Engineers (IEEE) physical layer
standard for Ethernet coaxial cable. It specifies the
carrier sense multiple access with collision detection
(CSMA/CD) access method on bus topologies. |
| |
| 802.5 |
|
|
An IEEE standard for token ring networks that provides
for a ring topology configuration (a closed set of active
taps con- nected by point-to-point links). Access to
the ring is granted when a token is received and passed
in a logical (and physical) ring sequence between the
workstations.
|
| |
| 10BASE-T |
|
|
A twisted-pair Ethernet cable standard that conforms
to IEEE 802.3 specifications and can carry data at 10
Mbps.
|
| |
| ANSI |
|
|
American National Standards Institute.
|
| |
| Attenuation |
|
| The decreasing
of a transmitted signal as it travels along a cable. The
longer the cable the more loss there will be. Above a
certain amount of loss, the cabling may not transmit network
data reliably. |
| |
| ACR
(Attenuation to Crosstalk Ratio) |
|
|
An indication of how much larger the received signal
of a pair is compared to the noise (NEXT) on the same
pair.
|
| |
| Bandwidth |
|
| Maximum information
carrying capacity of a channel. |
| |
| Basic
Link |
|
| A basic link is
a model defined by TSB-67. A basic link is similar to
what an installer might work with – including the
wall plate, horizontal wiring and first cross connection.
It is intended to be used by system designers and users
of data telecommuni- cations systems to verify the performance
of permanently installed cabling. A basic link consists
of up to 90 meters of horizontal cabling, a connection
at each end, up to 2 meters of test equipment cord from
the main unit of the field tester to the local connection,
and up to 2 meters of test equipment cord from the remote
connection to the remote unit of the field tester. |
| |
| Certification |
|
| An automated test
process that verifies that test results meet established
standards requirements. |
| |
| Channel |
|
| All elements of
the communications link connecting a DTE (typically a
PC or server) to a hub in the wiring closet. Includes
fiber cabling, patch cords, connections, and splices if
any. A channel is a model defined by TSB-67. It is similar
to what a user works with to transmit information between
a personal computer and its hub, or concentrator. A channel
includes up to 90 meters of horizontal cable, a work area
equipment cord, a telecommunications outlet/connector,
an optional transition connection close to the work area,
and two cross-connect connections in the telecommunications
closet. According to the TSB-67, the total length of equipment
cords, patch cords and jumpers shall not exceed 10 meters.
It is important to note that the connections to the equipment
at each end of the channel are not included in the channel
definition. |
| |
| Cladding |
|
| A protective layer,
made of glass or plastic, which surrounds the core. The
cladding has a lower index of refraction than the core,
which helps keep light in the core. |
| |
| Core |
|
| The center of a
fiber optic cable, usually made of extremely clear glass
or plastic, through which the light travels. |
| |
| EIA
(Electronic Industries Association) |
|
| An organization
of manufacturers of electronic parts and sys- tems. The
EIA sets such standards as the EIA-232 interface specification.
|
| |
| Electromagnetic
Interference |
|
| An unwanted signal
that enters the transmission line from fluorescent lights,
fan motors, etc. See also RF Interference. |
| |
| ELFEXT |
|
| Equal Level Far
End Crosstalk. This is far end crosstalk ad- justed for
attenuation. It can be thought of as far end ACR. |
| |
| FDDI |
|
| Fiber Data Distributed
Interface. |
| |
| Hertz
(Hz) |
|
| The frequency of
electrical vibrations (cycles) per second. One Hz equals
one cycle per second. |
| |
| IDC-type
Punch-Down Block |
|
| A twisted-pair
wiring panel in which each wire is placed in a pin, and
then punched into place, stripping the insulation in the
process. |
| |
| IEC |
|
| International Electrotechnical
Commission. |
| |
| IEEE |
|
| Institute of Electrical
and Electronic Engineers. A membership organization, including
engineers, scientists and students in electronics and
allied fields, that is involved with setting standards
for the computer and communications field. |
| |
| Impedance |
|
| The resistance
to the flow of alternating current in a circuit. |
| |
| ISO |
|
| International Standards
Organization. |
| |
| LAN
(Local Area Network) |
|
| A communications
network serving multiple users within a confined geographical
area (as in the same building or group of adjacent buildings).
It usually refers to the interconnection of personal computers.
Shared data is stored in a high performance PC called
a fileserver which serves as a remote disk drive to all
network users. Users may also share printers, modems and
other peripheral devices. |
| |
| Loopback |
|
| The shorting together
of wires in a connector so that a signal sent along the
wire returns to its place of origin. |
| |
| Megahertz
(MHz) |
|
| One million cycles
per second. See Hertz (Hz). |
| |
| Micron |
|
| 1 millionth of
a meter. |
| |
| Multi-mode |
|
| Fiber optic cabling
with a wider core (typically 50 or 62.5 microns) that
allows light to travel in multiple paths, such that it
is reflected back from the cladding back into the core
as it travels down the core. |
| |
| Near
End Crosstalk (NEXT) |
|
| The interference
measured on a wire adjacent to the wire on which the signal
is being sent. Near end crosstalk measurements show the
amount of signal leaking when measured close to the signal
generation point. If the crosstalk coupling across at
the near end is great enough, it can interfere with signals
coming from a remote point which are diminishing as they
reach the same spot. |
| |
| Noise |
|
| Any extraneous
signal that invades the transmission of electrical pulses
or frequencies along a cable. Noise is measured as im-
pulse or Root-Mean-Square (RMS). |
| |
| Nominal
Velocity of Propogation (NVP) |
|
| The speed of data
transmission along a cable relative to the speed of light
in a vacuum. |
| |
| OLB |
|
| Optical Link Budget. |
| |
| OTDR |
|
| Optical Time Domain
Reflectometer. A sophisticated fiber test tool that locates
fiber breaks, and can determine loss per connection, splice,
or segment. |
| |
| Patch
Cable |
|
| A short, flexible
cable terminated at both ends that is used to interconnect
LAN equipment. |
| |
| Pin |
|
| One of the male
leads on a multiple line plug, such as an RJ-45 connector
or an EIA-232 connector. |
| |
| Plenum
Cable |
|
| Cable certified
to be fire resistant and to produce a minimum of smoke.
It can be installed in the space between the false ceiling
and the floor or ceiling above, called the plenum. |
| |
| Punch-Down
Block |
|
| A central termination
point for twisted-pair cable. Each wire is placed in a
pin, then punched into place, stripping the insulation
in the process. See also 66-Type Punch-Down Block and
IDC- Type Punch-Down Block. |
| |
| Resistance |
|
| A property of a
conductor which resists or opposes the flow of current
in an electronic circuit. |
| |
| Return
Loss |
|
| This is a measure
of the overall uniformity of a link’s impedance relative
to 100 ohms. |
| |
| RF
Interference |
|
| An unwanted signal
that enters the transmission line from radio and television
transmitters. With this type of interference, the cable
acts as an antenna. See also Electromagnetic Interference
and Noise. |
| |
| Shield |
|
| An insulating material
used with coax or twisted-pair cable to reduce electrical
interference. |
| |
| Shielded
Twisted Pair (STP) |
|
| Two pair cabling,
with both pairs having its own individual shield, in addition
to an overall shield surrounding both pairs. STP is most
familiar to LAN users as the heavy black IBM Type 1 cabling
found in token ring networks. |
| |
| Single-mode |
|
| Fiber optic cabling
with a narrow core (8-9 microns) that only allows light
to travel in one path (i.e. one mode). |
| |
| TIA |
|
| Telecommunications
Industry Association. |
| |
| Time
Domain Reflectometry |
|
| A diagnostic technology
in which a pulse of known amplitude and duration is sent
along a cable. When an open or short is detected, a pulse
reflects back to the device generating the signal. The
device then measures how long the round trip took and
converts this to distance using the cable’s NVP. |
| |
| Twisted-Pair
Cable |
|
| Cable in which
two wires are wrapped (or twisted) around each other between
two and 12 times per foot of length. Most twisted-pair
cabling contains either four or 25 pairs of wires. Unshielded
Twisted-Pair (UTP) cable A common type of twisted-pair
cable that does not have a shield wrapped around the wires. |
| |
