Fiber Optics Illustrated Dictionary - Part 36 ppsx

Fiber
Optics
Illustrated
Dictionary
compress-send-decompress
schemes,
with
the
com-
pression
needed
only
to
speed
transmissions,
and
thus
not
degrading
the
quality
of
the
original.
See
facsimile
mode, Huffman encoding, TIFF-FX,
RFC
2301,
RFC
2304,

RFC
2305.
facsimile
mode
Facsimile
machines
have
a
number
of
operating
modes,
including various regular
and
fine
resolutions,
and
can
be
manipulated
to
send
in
monochrome
or
grayscale,
depending
on
the
capa-

bilities of
the
sender
and
receiver,
and
the
software
or
hardware.
Most
fax
machines
and
fax/modems
send
in
Group
3 standard
and
fine
modes,
that
is
203;dX;d98
pixels
and
203;dX;d
196
pixels. Other

modes
have
been
defined
(Group
3
203;dX;d39
I -
su-
perfine;
Group
4
400;dX;d400
- standard),
but
they
are
not
widely
supported
in
consumer-priced
prod-
ucts.
A
fax
can
be
only
as

good
as
the
weakest
link
in
the
transmission.
If
the
sending
fax
sends
in
the
low-
est resolution, a higher resolution receiving
fax
doesn't
improve
the
image.
Conversely,
if
the
send-
ing
fax
uses
fine

resolution,
but
the
receiving
fax
can
only
support
standard
resolution,
the
details
will
still
be
lost.
Since
the
orientation
of
most
faxes
is
portrait,
and
the
orientation of most computer monitors
is
landscape,
fax/modem

software
usually
has
zoom,
pan,
and
rotate
features
to
aid
in
viewing
documents.
facsimile modem,
fax
modem A
fax
modem
system
consists of a fax-enabled
data
modem
(one
which
works
in
two
modes)
hooked
to

a
computer,
some-
times
combined
with
a
scanner.
Instead
ofcreating a
document,
printing
it,
feeding
it
through
the
fax
ma-
chine,
receiving
aprinted
page
at
another destination
fax
machine, and then perhaps even typing or
rescanning
(and
OCR-ing)

the
printout
back
into
a
computer
at
the
other
end,
the
fax
modem
system
sends
a
digital
fax
directly
from
the
software
appli-
cation
that
created
the
document,
to
the

receiving
end.
Or,
ifa
scanner
is
used,
the
system
sends
the
scanned
file
as
the
fax.
If
the
receiving
device
is
a
fax
modem
system,
rather
than
a
fax
machine,

then
the
fax
goes
directly
to
the
computer
hard
drive,
and
no
paper
is
used
in
the
transaction.
Optionally,
a
fax
machine
may
connect
to
a
local
net-
work
so

that
users
can
be
notified if a
fax
has
been
received
or
even
select
an
option
to
view
the
fax
on
a
computer monitor
(thus
providing hybrid
fax
ma-
chine/fax
modem
capabilities).
In
business

environments
some
people
erroneously
use
fax
machines
when
they
should
be
doing
direct
data
transfers.
This
is
a
common
scenario:
the
main
office
ofa corporation creates a
new
80-page
policy
manual
and
wants

to
distribute
it
to
all
ten
branch
offices.
The
branch
offices
would
like
an
electronic
copy
in
order
to
customize
it
for
their
needs,
or
to
easily
make
corrections
as

directed
by
the
main
of-
fice,
etc.
The
typist
types
a
copy,
faxes
80
pages
to
each
of
the
ten
branch
offices;
880
pages
are
gener-
ated
in
all,
the

original,
and
the
10
branch
copies.
Now
the
typists
at
each
branch
office
retype
the
document
into
their
word
processors,
thus
duplicating
the
work
already
done.
Rather
than
always
using

a
fax
machine,
there
are
342
better
ways
to distribute
some
types
of
documents.
The
first
is
a slight improvement.
By
using
a
fax!
modem
software
program
to
send
the
document
di-
rectly

to
each
branch
to
another
fax/modem
program,
no
paper
is
printed
until
the
documents
are
complete
to
each
branch's satisfaction,
and
the
completed
cus-
tomized
documents
can
be
OCR-scanned
back
into

a
word
processing
text
file
at
the
destination.
A better solution
is
to
send
the
original
file,
in
docu-
ment
format,
through
a
modem
or
through
the
Inter-
net,
to
each
branch

office,
where
the
secretaries
can
load
the
received
file
directly
into
the
word
proces-
sor.
This
can
be
accomplished
by
putting
the
file
on
an
FTP
site,
and
notifying
the

branches
that
they
can
access
the
site
and
download
the
latest
version
of
the
file.
If
different
word
processors
are
being
used,
the
original
can
be
saved
in
Microsoft Interchange For-
mat

(also
known
as
RTF
or
Rich
Text
Format), a
widely supported
format
that
can
be
read
and
saved
by
all
major
word
processing
programs.
The
best
solution
to
document exchange
may
be
to

have
a
secure
centralized
online
document
repository
which
can
be
accessed
and
modified
dynamically
by
all
branches
through
an
Internet
or
private
network
connection.
Fax
machines
are
a great resource
for
sending

short
documents,
but
they
are
not
the
best
solution
for
all
document transfers,
and
the
Internet
provides
distant branches
with
a
way
to
dynamically
produce
and
maintain
documents
without incurring
long-distance charges. Integrated
data,
video,

and
voice
services
are
increasingly offered
by
telecom-
munications carriers; facsimile communications
are
being superseded
to
some
degree
by
email
attach-
ments,
especially
PDF
files.
See
facsimile
device,
fac-
simile fonnat, facsimile history, facsimile
modes,
Portable Document
Format.
facsimile switch An external switching
device

that
allows
a single
phone
line
to
be
used
for
more
than
one
phone-related piece of
equipment.
Fax
switches
often
can
also
handle
telephone
answering
machines
and
computer
modems.
The
fax
switch
is

attached
between
the
phone
line
plug
and
the
various
phone
devices.
When
a
call
comes
through,
the
device
evalu-
ates
the
tones
and
decides
whether it's a
voice
call, a
modem
call,
or

a
fax
call,
and
routes
the
call
to
the
appropriate
device.
Unfortunately,
most
fax
switches
can't detect
when
a
manual
fax
machine
is
going
to
send
a
fax
if
the
call

originated
as
a
voice
call.
If
the
person
dials
the
phone manually
and
then
wants
to
switch
over
to
a
fax
call
after
the
connection
is
es-
tablished,
many
fax
switches

can't
revert
to
data
mode
(newer
ones
may
be
switchable
on
receiving a
par-
ticular
code).
In
spite of
that
limitation, it's a
great
tool
for
homes,
home
offices,
and
small
businesses
that
can't

afford
extra
phone
lines.
fade
To
diminish
in
strength,
loudness,
or
visibility.
In
video
or
audio
editing,
fading
is
deliberately
used
to
provide transitions
that
are
perceptually
pleasing.
In
data
or

broadcast transmissions,
fade
is
usually
an
undesirable effect
due
to
various
factors
such
as
dis-
tance, loss of signal, obstructions, interference,
etc.
Undesired fade
can
sometimes
be
reduced or
© 2003 by CRC Press LLC
eliminated
by
amplifiers, repeaters, robust
wiring
mediums,
and
good
insulation.
fade margin

Signal
losses
in
satellite
systems
can
occur
from
scattering,
absorption,
and
various
subtle
types
of interference. Consequently various
fade
margins
are
incorporated
into
the
design
of
the
sys-
tems,
and
they
will
vary

depending
on
the
degree
of
fade
expected
from
various
sources
and
on
the
length
of
the
broadcast
waves,
with
shorter
waves
generally
being
more
subject
to
fade.
FahrenheitscaleA
temperature
scale

that
designates
32
degrees
for
the
freezing
point
of
water
at
normal
pressure
and212
degrees
for
the
boilingpointofwa-
ter
at
normal
pressure,
and
other
points
relative
to
these.
See
centigrade

scale,
Celsius
scale.
Fahrenheit,Daniel Gabriel (1686-1736) A
Polish-
born
German
scientist
who
established
the
widely
used
Fahrenheit
scale.
Zero
degrees
was
designated
as
the
temperature
of a
mix
of
ice,
water,
and
salt,
and

90
degrees
was
considered
to
be
the
temperature
of
the
human
body
(in
fact,
it's
closer
to
98.6
degrees).
See
Riimer,
Ole
Christensen.
failsafe A
designation
that
indicates
that
failure
ofa

system
is
unlikely
or
impossible,
or
that
backups
are
available
if
needed.
In
networking,
few,
if
any,
sys-
tems
are
completely
failsafe,
but
there
are
steps
that
can
be
taken

to
prevent
problems,
such
as
the
use
of
surge
suppressors,
backup
power
systems,
redundant
data
storage
or
broadcast
signals,
etc.
See
fault
toler-
ant,
redundant
array
of
inexpensive
disks.
fake code

See
pseudocode.
fallback A
contingency
mode,
plan,
or
operation.
In
communications,
a
designation
for
another
speed
or
mode
of
operations
if
the
current
mode
is
not
func-
tioning
as
well
as

might
be
desired.
Many
modems
may
fall
back
(two
words)
to
a
slower
speed
if
the
connect
negotiation
doesn't
work
at
higher
speeds.
Many
communications
programs
may
fall
back
to

smaller
packet
sizes
if
there
is
a
lot
of
noise,
or
other
impingements
on
a
data
file
transfer.
In
software,
a
fallback
(one
word)
may
be
one
in
which
the

appli-
cation
or
operating
system
goes
to
another
mode
or
another
program
if
some
error
condition
or
slowdown
is
detected.
A
network
may
go
to
a
fallback
route
if
the

usual
one
is
not
available
or
not
responding
as
expected.
falsing
Spurious
signals
that
accidentally
are
inter-
preted
by
a
system
as
commands,
or
that
are
deliber-
ately
introduced
to

fool
a
system,
usually
for
unau-
thorized
purposes.
In
telephone
systems,
certain
situ-
ations
can
be
simulated
by
playing
particular
tone
se-
quences,
so
the
system
is
fooled
into
switching,

trans-
ferring,
or
connecting
long-distance
or
other
types
of
calls.
In
transmissions
control
for
satellites
and
other
radio-controlled
devices,
environmental
noise,
falsely
interpreted
signals,
etc.
can
have
major
consequences
if

the
system
thinks
it's a
command
and
acts
upon
it.
fan
1.
Fan
of
science
fiction.
Since
there
are
a
large
number
of
software
developers
who
are
science
fic-
tion
fans,

they
have
co-opted
this
term
into
many
computer-related situations,
video
games,
simula-
tions,
and
virtual
reality
environments.
2.
An
active
cooling
device
(as
opposed
to
passive
devices
such
as
heat
sinks)

often
used
to
cool
computers
so
that
chips
and
other
components
are
kept
at
optimum
op-
erating
temperatures.
FAN
See
flexible
access
network.
fanfold
See
z-fold.
fanout A
device
that
facilitates

the
separation
of
in-
dividual
fibers
in
a
fiber
optic
cable
bundle,
enabling
them
to
be
more
easily
handled,
attached,
configured,
or
repaired.
After
being
fanned,
individual
strands
may
be

channeled
through
afurcation unit
for
rout-
ing
to
its
destination.
See
furcation
unit.
See
fantail.
FANP
See
Flow
Attribute
Notification
Protocol.
Fantail Fiber
Optic
Wiring
Bundle
A fantail wiring bundle secured
at
the
point
where
it connects to the electronic components, with con-

nectingpoints
for
individualfibers
fanned
out
for
cou-
pling
with the appropriate connectors. Individual fi-
berpigtails typically haveprotective caps, in prepa-
ration
for
adding a connector,
or
will have a connec-
tor already attached to protect the precision-cut
and
polishedterminalpoint. They
may
be
color coded to
facilitate
the correct connections. [NASAILangle
photo, 1999.J
fantail A
descriptive
term
for
a
wiring

bundle
that
is
secured
somewhat
near
the
point
at
which
the
wire
connectors
spread
apart
for
attachment
to
a
wiring
rack,
thus
creating a
shape
that
fans
out
from
the
bundled

point.
The
strap
that
secures
the
bundle
aids
in
holding
the
wires
together
if
one
or
more
of
the
wire
connectors
are
disconnected,
as
they
will
hang
a
few
inches

below
the
rack
for
easy
location
and
re-
attachment,
if
desired.
The
fantail
configuration
also
makes
it
easier
to
disconnect
and
reconnect
the
en-
tire
bundle
of
wires.
See
fanout.

FAQ
See
frequently
asked
questions.
far end crosstalk
FEXT.
When
wires
are
packed
to-
gether
tightly,
and
signals
are
travelling
through
most
or
all
the
wires,
the
potential
for
interference
from
crosstalk

increases.
Far
end
crosstalk
is
a
type
of
in-
terference
originating
from
multiple
signals
travel-
ling
in
the
same
direction, typically
through
wire
pairs,
as
in
common
copper
twisted-pair
installations.
FEXT

directly effects bit error rates
(BERs),
as
it
343
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
cannot
be
cancelled
as
easily
or
as
effectively
as
near
end
crosstalk
(NEXT).
See
near
end
crosstalk.
farad A
unit
ofcapacitance

equal
to
one
coulomb
(of
electricity) divided
by
(a
potential of)
one
volt.
Named
after
Michael
Faraday.
faradaic
Relating
to
an
asymmetric alternating
cur-
rent
(AC)
produced
by
an
induction
coil.
faraday A
measure

ofelectrical
charge
transferred
in
the
process
ofelectrolysis per weight of
an
ion,
or
element,
that
is
equal
to
about
96,500
international
coulombs
(or
96,490
absolute
coulombs).
Named
af-
ter
Michael
Faraday.
Faraday
cage

Astructure, usually
mesh-
and
cage-
like,
to
isolate
a
person,
device,
or
electronic
system
from
damage
or
interference
from
outside electrical
sources.
These
may
sometimes
be
seen
in
science
museums
where
electrical

devices,
especially
large
Van
de
Graaff
generators,
are
demonstrated.
Named
after
Michael
Faraday.
Faraday DarkSpace
In
a
cathode
discharge
tube,
a
region
between
the
positive
column
and
the
negative
glow
that

appears
dark.
Regions
in
the
tube
become
easier
to
distinguish
if
the
pressure
is
lowered
in
a
tube
that
has
some
air
in
it
(normally
air
is
removed
to
extend

tube
life
and
effectiveness).
Then
it
becomes
possible
to
distinguish
the
Faraday
Dark
Space
as
a
region
just
outside
a
pale
negative discharge
glow,
which
in
turn
terminates
in
Crookes Dark Space,
which borders

the
outside glow
of
the cathode.
Named
after Michael Faraday.
See
Crookes Dark
Space.
Faraday dynamo A
historic
electrical generator
de-
veloped
in
1832
by
Michael
Faraday.
Faraday effect A basic magneto-optical effect
in
which
a
plane
ofpolarization of
light
in
a
magnetic
field,

traveling
parallel
to
the
lines
of
magnetic
force,
can
be
rotated
to
another
plane
by
a transparent
iso-
tropic
medium.
Named
after
Michael
Faraday,
who
described
it
in
1846,
this
effect

was
studied
further
three
decades
later
by
John
Kerr.
The
distinction
be-
tween
the
Faraday
effect
and
the
Kerr
magneto-opti-
cal
effect
is
that
Faraday
focused
his
attention
on
a

beam
that
was
transmitted
through
the
magnetic
ma-
terial,
while
Kerr
focused
on
a
beam
that
was
reflected
off
the
magnetic
material.
The
Faraday
effect
can
be
seen
in
a

number
of telecommunications technolo-
gies.In satellite communications,
the
plane ofpolar-
ization of
radio
waves
traveling
through
the
iono-
sphere
rotates
about
the
direction
of
propagation,
par-
ticularly
at
lower
frequencies.
See
Kerr
magneto-op-
tical
effect.
Faraday effect, acoustic

The
Faraday effect
was
described
by
Michael
Faraday
more
than
150
years
ago.
It
is
a
basic,
fundamental
effect
that
is
exhibited
in
many
different
phenomena
and
is
of continuing
interest
to

scientists,
both
as
to
its
properties
and
its
practical
applications.
The
acoustic
Faraday effect
is
the
acoustic
analog
ofFaraday's magneto-optical
ef-
fect.
Typically,
liquids
do
not
propagate transverse
waves,
but
L.D.
Landau,
in

1957,
predicted that a
quantum
liquid
phase
of
3He
might
exhibit
transverse
sound
waves
under
specific
conditions.
Lee
et
al.
have
344
observed rotation of
the
polarization
of
transverse
sound
waves
in
superfluid
3He-B

in
amagnetic field,
lending
support
to
Landau's prediction.
See
Faraday
effect.
Historic Faraday Electromagnet
This Faraday electromagnet, cobbled out
of
avail-
able materials. was wound partly from Faraday
s
wife spel/icoat. [Classic Concepls ilIusrralion.}
Faraday-Stark effect A
novel
effect resulting
from
the
combination of
the
Faraday
magneto-optical
ro-
tation
and
quantum-defined
Stark

effect.
This
phe-
nomenon
enables
an
electrical
field
to
be
used
to
in-
fluence
a Faraday
or
magneto-optic
Kerr
rotation.
It
is
a
photonic
effect
that
was
discovered
in
the
mid-

1990s
which,
along
with
linear polarizers,
may
have
applications
for
future
high-frequency modulation
devices.
The
Faraday-Stark effect
was
described
by
Lee
et
al.
in
Applied Physics
in
1996,
and
Faraday-
Stark
magneto-optoelectronic
(MOE)
devices

were
patented
by
Lee
and
Heiman (U.S. #5,640,021,
1997).
See
Faraday
effect,
Stark
effect.
Faraday, Michael (1791-1867) An
English
physi-
cist
and
chemist
who
was
apprenticed
to
a
bookbinder
at
the
age
of
13.
He

took
time
to
read
the
books
and
to
listen
to
local
lectures
by
Humphry
Davy,
becom-
ing
his
laboratory
assistant
in
1813.
Faraday
went
on
to
conduct extensive experiments
in
electricity
and

magnetism.
He
passed
electrical
currents
through
so-
lutions
and
observed
their
effects,
adding
new
knowl-
edge
to
the
discoveries of
A.
Volta.
Faraday
demon-
strated
that
the
amount
of
an
element

deposited
at
an
electrode
is
proportional
to
the current flowing
through
the
solution.
In
1831,
he
demonstrated
that
an
electrical current
can
induce
a current
in
a
differ-
ent
circuit
and
made
a historic
entry

in
his
journal
linking
electricity
and
magnetism.
The
following
year
he
constructed a
basic
generator, calling
it
adynamo.
Faraday also studied
the
properties of
metals
and
glass
and
developed
new
types
of
optics.
He
coined

© 2003 by CRC Press LLC
the
tenns
electrolyte,
electrode,
and
ion.
Further
im-
portant
investigations
of
inductance
in
electrical
cir-
cuits
by
other
scientists
grew
out
ofFaraday's
work.
Many
electrical
effects
have
been
named

after
him.
See
Davy,
Humphry.
Faraday's laws
Michael
Faraday investigated
the
phenomena related
to
decomposition
by
galvanic
current
and
made
some
important discoveries that
have
been
investigated
and
variously
stated
by
suc-
ceeding
scientists.
Generally,

Faraday's
laws
are
de-
scribed
as
follows:
I.
in
electrolytic decomposition,
the
number
of
ions
charged
or
discharged
at
an
electrode
is
pro-
portional
to
the
current
passed;
2.
the
amounts

of
different
substances
deposited
or
dissolved
by
the
same
quantity
ofelectricity
are
proportional
to
their equivalent
weights;
3.
when
passing
a constant
quantity
ofelectricity
through
different
electrolytes,
the
masses
of
the
ions

set
free
at
the
electrodes
are
directly
pro-
portional
to
the
atomic
weights
of
the
ions
di-
vided
by
their
valence.
Faraday
called
his
discovery
the
"law
of
definite
elec-

trolytic action." It
was
opposed
by
Berzelius
and
those
who
adhered
to
Volta's
theory
of
galvanism.
Through
subsequent
experiments,
Faraday's
concepts
have
been
refined
and
confirmed,
and
his
discover-
ies
are
now

known
as
Faraday's
laws.
Farber, David
J.
Originally a
computer
consultant
to
the
Rand
Corporation
in
the
late
1970s,
Farber
later
became
a cofounder of
CSnet
(Computer
Science
Network), NSFNet,
and
others.
In
1995,
he

was
awarded
the
SIGCOMM
Award
for
lifelong
contri-
butions
to
his
field.
Farber
has
served
on
the
boards
of
AT&T
and
several
other
industry
telecom
compa-
nies,
as
well
as

the
Electronic Frontier
Foundation
and
the
Internet
Society.
In
January
2000,
the
Fed-
eral
Communications
Commission
(FCC)
announced
his
appointment
as
Chief
Technologist
for
the
FCC.
He
is
known
for
his

online
discussion
list "interest-
ing
People."
FARNet
See
Federation of
American
Research
Net-
works.
Farnsworth, Philo Taylor (1906-1971) A preco-
cious
American
musician
and
inventor
who
built
an
electric
motor
at
about
12
years
of
age
and

described
a
television
system
to
friends.
He
is
reported
to
have
shown
a
drawing
of
the
idea
to
J.
Tolman,
a
teacher,
in
1922.
Fortunately,Tolman
later
remembered
the
incident
and

produced
the
drawing,
or
the
young
Farnsworth
might
not
have
received
credit
for
being
one
of
the
earliest
inventors
of
television
technology.
Farnsworth
kept
working
on
the
idea,
submitted a
patent

application
in
January
1927,
and
successfully
transmitted
his
first
TV
image
in
September
1927.
The
television
patent
was
awarded
in
August
1930
(U.S.
#1,773,980).
The
versatile
inventor
also
developed
several

types
of
amplifying
systems,
a
system
of
pulse
transmis-
sion,
a
projection
system,
a
microscope,
and
a
type
of
cold
cathode-ray
tube
(CRT),
securing
hundreds
of
technology
patents
during
his

lifetime.
It
should
be
noted that biographers
and
Farnsworth himself
credit
his
wife
Elma
"Pem"
Gardener-Farnsworth
as
contributing significantly
to
the
construction
of
his
devices.
In
September
1983,
the
U.S.
Postal
Service
com-
memorated

the
achievements
of
Philo
T.
Farnsworth
with
a
20-cent
stamp
and
first
day
cover
and
later
is-
sued
a
33-cent
portrait
stamp
from
the
Great
Ameri-
can Inventors series. See television history.

Farnsworth Historic Imaging
Tube

.~.
Farnsworth steenage drawing
of
his concept
of
a
historic television system emergedduringpatentdis-
putes in the 1930s. {Philo
T.
Farnsworth, 1922.J
FAS
1.
See
facility-associated
signaling.
2.
See
frame
alignment
signal.
fast busy A
telephone
busy
signal
that
is
distinctive
in
that
it

repeats
at
twice
the
rate
ofaregular
busy.
A
regular
busy
signal indicates
the
caller's
phone
is
unavailable (it's
off-hook
or
in
use),
whereas
a
fast
busy
indicates
that
all
trunk
lines
are

busy,
and
the
call
cannot
currently
be
routed
to
the
destination.
FastEthernetA
version
ofEthernet
enhanced
to
in-
crease
its
10
Mbps
capacity
up
to
100
Mbps
over
cop-
per
or

fiber,
which
brings
it
into
the
high
speed
net-
working range along with asynchronous transfer
mode
(ATM)
and
FDDI.
This
enhanced capability
requires
the
upgrade
ofother
devices
such
as
hubs
and
network
cards,
partly because Ethernet
hubs
can

be
cascaded,
whereas
Fast
Ethernet
hubs
are
stacked.
Fast Ethernet
is
an
international
open
IEEE
standard
(802.3u,
1995)
used
in
medium-scale
networks
such
as
campus
backbones.
See
Fast Ethernet
Alliance,
Gigabit
Ethernet.

Fast Ethernet Alliance
An
open
trade
association
established
to
develop
and
promote Fast Ethernet
technologies
for
existing
voice-grade
traditional
cop-
per twisted
pair,
founded
in
July
1993.
A
major
goal
of
the
Alliance
was
to

standardize
100
Mbps
Ether-
net
technology.
By
1994,
it
had
submitted
100Base-
TX
and
1
OOBase-
T4 wiring specifications
for
con-
sideration
to
the
IEEE
for
inclusion
in
the
IEEE
Fast
Ethernet

1
OOBase-
T
standard.
The
Alliance
member-
ship
totaled
more
than
four
dozen
telecommunications
345
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
vendors
including
well-known
companies
such
as
NCR
Microelectronics,
National
Semiconductor,

Sun
Microsystems.
Fast
Ethernet
was
adopted
officially
in
June
1995
by
the
IEEE
802.3
group.
See
Fast
Ether-
net.
fast Fouriertransform
FFT.
See
Fourier
transform,
fast.
Fast
SCSI
A
means
of

configuring
SCSI
to
provide
faster
transmission
speeds,
up
to
10
Mbps.
There
have
been
a
number
of
variations
on
the
SCSI
standards.
One
of
the
more
commonly
implemented
versions
is

SCSI-2.
See
Small
Computer
System
Interface
for
a
detailed
description
of
SCSI
technology.
FastIP, FastInternet ProtocolA
3Com
commercial
product
in
which
just
the
first
datagrams
of
the
IF
traf-
fic
are
passed

through
the
router
and,
ifa
direct
path
is
found,
subsequent
ones
may
bypass
the
router
us-
ing
Next
Hop
Resolution
Protocol
(NHRP).
It
is
em-
bedded
in
local
area
network

(LAN)
adaptors
and
implemented
in
LAN
switches
rather
than
in
Inter-
net
Protocol
(IP)
routers.
See
IP
switching.
FAT
1.
File Allocation Table. See
FAT
format.
2.
final
acceptance
testing.
FAD
See
fixed

access
unit.
fault A
defect,
incorrectly
functioning
system,
mis-
take,
or
accident.
In
fiber
optic
cables,
faults
may
in-
clude
crystallization
during
fabrication,
bubbles,
un-
desired
particles
(apart
from
deliberate
fiber

doping),
misalignments,
incorrect
coupling
or
bonding,
exces-
sive
bends,
and
dispersion
problems.
fault isolation
In
electronic
circuitry
or
software
de-
bugging,
a
troubleshooting
strategy
for
isolating
the
location ofa
problem.
In
circuitry, it

may
involve
shutting
down
parts
of
the
system,
wiring
in
shunts
or
bridges,
or
selectively
stimulating
particular
areas.
In
software,
it
may
involve
setting
breakpoints,
print-
ing
debug
messages,
or

tracing
particular
variables.
See
bridge,
shunt,
trace.
fault threshold
The
level
at
which
a system's
struc-
ture
or
function
is
considered
to
be
compromised.
This
may
be
a
certain
number
of
lost

packets,
a
speci-
fied
electrical level, a certain number of physical
flaws,
or
any
other
measures
particular
to
a
system
that
affect
its
integrity
and
functioning
for
aparticu-
lar
purpose.
fault tolerant A
fault
tolerant
system
is
one

that
is
designed
so
ifa
problem
occurs,
the
entire
system
or
important
parts
of
the
system
will
continue
to
func-
tion
until
the
problem
is
corrected.
Thus,
system
re-
dundancy,

backups,
secondary
routines
or
hardware
paths,
etc.
can
be
incorporated
to
increase
fault
toler-
ance.
Good
computer
operating
systems
are
designed
so
that
individual
applications
don't
crash
the
system.
The

application
itself
may
crash,
or
need
to
be
"killed"
(by
killing
the
individual
processes
associated
with
the
program),
but
the
system
can
handle
the
crash
without
affecting
other
programs
or

the
general
op-
erations
and
will
clean
up
stray
files,
memory,
etc.
See
Byzantine
Generals
problem,
failsafe.
fax
colloq.
facsimile.
See
facsimile
machine.
fax
mode
See
facsimile
mode.
FB
See

framing
bit.
346
FBT
See
fused
biconic
taper.
FBus
Frame
Transport
Bus.
FC
1.
See
feedback
control.
2.
frame
control.
FC- connector Arelatively
common
coupling
part
for
fiber
optic
connections
that
physically

resembles
ST-
connectors,
but
with
a
friction
rather
than
a
bayo-
net
mount.
FC-
connectors
are
used
to
couple
single-
mode
fiber
connections.
They
are
also
available
in
hotmelt
styles.

FC-x
In
the
Fibre
Channel
hierarchical
model,
a
se-
ries
of
services
and
protocols.
For
more
detailed
information,
see
Fibre
Channel,
including
the
Fibre
Channel
Layers
chart.
FC-x Function
Notes
FC-O

physical
media,
transport
speeds,
re-
ceivers,
and
transmitters
are
defined
at
this
level
FC-l
encodings
transmission
encodings
and
decodings
FC-2
signaling a protocol for specifying
mechanisms and rules for
transfering
data
blocks,
con-
trolling
data
flow,
and

error
detection
mechanisms
FC-3
services
common services for
N
Ports
on
a
node
FC-4
protocols upper level protocols in
terms of channels
and
net-
works
(e.g.,
SCSI
and
ATM)
that
map
into
the
system
FCA
See
Fibre
Channel

Association.
FCIA
See
Fibre
Channel
Industry
Association.
FCC
See
Federal
Communications
Commission.
FCC Glossary ofTelecommunications Terms
See
Glossary
of
Telecommunications
Terms,
FCC.
FCLC
See
Fibre
Channel
Loop
Community.
FCS
1.
See
Federation
of

Communications
Services.
2.
See
Fibre
Channel
specifications.
3.
See
Frame
Check
Sequence.
4.
Fraud
Control
System

FCSI
See
Fibre
Channel
Systems
Initiative.
FCW
See
Federal
Computer
Week
Magazine.
FDD

See
floppy
disk
drive.
FDDI
See
Fiber Distributed
Data
Interface.
FDM
See
frequency
division
multiplexing.
FDMA
See
frequency
division
multiple
access.
FDMS
See
Fiber
Dispersion
Measurement
System.
feature
code
A
number

or character
sequence
used
to
activate
a
feature
on
a
phone
system,
such
as
speed
dialing,
last
number
redial,
etc.
These
are
more
com-
mon
on
multiline
business
phones
than
on

residen-
tial
phones.
feature connectorA
connector
for
coupling
a
periph-
eral
card
or
device
to
another peripheral
card,
such
as
a
video
graphics
adapter,
so
the
second
card
can
perform
direct
memory

access
(DMA)
through
the
card's
bus,
without
having
to
load
the
system
bus.
The
feature
connector
is
commonly
used
on
VESA
-com-
patible
systems.
© 2003 by CRC Press LLC
Feature
Group
Switching Arrangements
feature phone A phrase
for

phones
that
have
extra
features.
Sometimes
the
features improve function-
ality (redial, speakerphone, channel, etc.), but
some-
Feature Groups Designated groups representing
various
types
oflong-distance carrier switching
ar-
rangements that
are
part
of
the
Bell Operating
Com-
panies
(BOC)
system.
Group
A
Group
B
Group.C

GroupD
A subscriber
line
connection
rather
than
a trunk
connection
to
a
local
exchange
carrier's
network.
A
trunk
connection
that
uses
an
authorization
code
for
billing.
Used
in
areas
where
it
is

not
practical
to
offer
Feature
Group
D
(Equal
Access
services),
such
as
some
older
switching
systems,
and
independent
services.
The
older long-distance
services
offered
by
local
exchange
carriers
to
AT&T
before

divestiture.
Mutually
exclusive
with
Feature
Group
D.
Equal
Access
services,
facilities
and
signaling specifications,
established
since
divestiture
and
implemented
in
the
mid-1980s.
Mutually
exclusive
with
Feature
Group
C.
times
they
are

just a marketing enticement
and
may
not
be
very useful.
FEe
1.
See
Forwarding Equivalence
Class.
2.
See
forward error correction.
FECN
See
Forward Explicit Congestion Notifica-
tion.
Federal Communications
Commission
FCC.
A
sig-
nificant
U.S.
federal regulatory organization origi-
nally created through the Communications Act
of
1934,
evolving

from
the
formation
of
the
Federal
Ra-
dio
Commission
(FRC)
in
the
Radio
Act
of
1927.
The
original mandate of the
FCC
was
to
regulate the
E~~==:~~:t~l.::~]~:F~::~:~~~
iB
time
slots,
and
callsigns. Since
then,
its

jurisdiction
has
been
broadened,
reflecting
the
growth
in
telecom-
munications
in
general.
The
Commission
is
directly
responsible
to
the
U.S.
Congress.
The
FCC
has
a powerful role
to
play
in
the
fair

and
equitable enactment
and
distribution oftelecommu-
nications resources
in
accordance with
the
Telecom-
munications Act of
1996.
It
is
the
responsibility
of
the
FCC
to
see
that
the
Act
meets
its
goals
of
open-
ing
the

telecommunications business
to
anyone,
and
of
promoting fair competition
in
the
industry.
The
FCC
now
also
oversees product emissions,
en-
suring that computing devices
do
not
emit
harmful
radiation or unharmful radiation
at
levels that
may
nevertheless interfere
with
other radiant technologies
such
as
radio

waves.
The
FCC
overall organization consists ofa number
of
commissioners, about nine offices
(public
affairs,
plans
and
policy,
general counsel, etc.)
and
six
bu-
reaus.
See
Primary Divisions
chart.
See
Communi-
cations
Act
of
1934.
/>Primary
Divisions
of
the Federal Communications Commission
FCC

Bureau
Responsibilities
Common
Carrier
(CCB)
Enforcement,
pricing,
accounting,
program
planning,
network
services,
and
wire
line
services.
Wireless
Telecommunications
(WTB)
Domestic
wireless
communications,
including
paging,
cell
phone,
PCS,
and
radio,
excepting

satellite
communications.
This
bureau
is
further
subdivided
into
Commercial
Radio,
Enforcement,
Policy,
Private
Radio,
Licensing,
Customer
Services,
and
Auctions
divisions.
Mass
Media
(MMB)
Audio
service,
enforcement,
policy
and
rules,
video

services,
administration,
and
inspections.
Compliance
& Information
(CIB)
A
national
call
center,
and
infonnation
resources,
management,
compliance,
technology,
and
regional
offices.
International
International
planning
and
negotiations, satellite
and
radio
communications,
and
general

administration.
Cable
Services
(CSB)
Consumer
protection
and
competition,
engineering
and
technical
services,
policy
and
rules,
public
outreach,
management.
347
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
Federal
Communications Commission classes,
FCC classes
A
series
of

designations
or
ratings
ap-
plied
by
the
FCC
to
electronics
devices.
These
are
primarily
intended
to
help
prevent
interference
from
devices
like
computers
that
may
affect
electromag-
netic
broadcast
waves

such
as
radio
and
television
signals.
If
you
have
tried
to
use
a
cordless
phone
near
a
computer
and
experienced
interference,
you
are
fa-
miliar
with
the
type
of
problem

excess
emissions
can
create.
Many
commercial
video
devices,
for
example,
are
labeled
'For
Commercial
Use
Only'
to
comply
with
FCC
regulations.
Federal
Computer
Week
Magazine
FCW.
A
news-
paper
providing

up-to-date
news
and
product
infor-
mation
to
U.S.
government
computer
technology
us-
ers
on
sources
and
types
of
federal
information
tech-
nology
(IT).
It
especially
focuses
on
desktop,
client-
server,

and
enterprise
computing
and
issues
of
vol-
ume
procurement.
FCW
publishes
online
and
print
editions
and
maintains
an
online
archive
of
past
in-
formation.
FederalInformation Processing Standard
FIPS.
A
set
of
standards

for
document
processing,
search,
and
retrieval.
Examples
include
FIPS
PUB
180-1
(secure
hash
standard)
and
FIPS
PUB
144
(digital
commu-
nication
performance
parameters).
A
number
ofFIPS
publications
are
based
upon

ANSI
and
CCIT
stan-
dards.
Federal Networking Council
FNC.
The
FNC
re-
ports
to
the
Federal
Coordinating
Committee
on
Sci-
ence
Engineering
and
Technology
and
was
chartered
by
the
National
Science
and

Technology
Council's
Committee
on
Computing,
Information
and
Commu-
nications
(CeIC).
It
provides
a
focal
point
and
forum
for
networking
collaboration
among
U.S.
federal
agencies
with
regard
to
education,
research,
intercom-

munications,
and
network
operations.
Since
1997,
the
various
activities
of
the
FNC
have
been
carried
out
through
the
Large
Scale
Networking
(LSN)
group.
/>Federal
Standard
Glossary
of
Telecommunica-
tions Terms
See

Glossary
of
Telecommunications
Terms,
Federal
Standard.
Federal Technology Service
FTS.
A
service
of
the
U.S.
General
Services
Administration
(GSA)
that
provides
infonnation
technology
and
network
ser-
vices
to
U.S.
government
agencies,
including

its
mo-
bile
workforces.
/>FederalTelecommunications StandardsCommit-
tee
FTSC.
A
U.S.
government
agency
that
promotes
the
standardization of
communications
interfaces,
including
computer
networks.
The
FTSC
is
chaired
Category
Class
A
Class
B
Notes

Computing
devices
rated
for
office
use
and
that
may
not
be
used
in
the
home.
Computing
devices
rated
for
home
use.
by
the
Chiefof
the
Technology
and
Programs
Divi-
sion.

Through
the
work
of
its
technical
subcommit-
tees,
it
is
the
primary
telecommunications
standards
mechanism
supporting
the
National
Communications
System
(NCS).
The
FTSC
liaises
with
and
evaluates
the
development
of

national
and
international
stan-
dards
and
develops
federal
standards
recommenda-
tions
or
the
standards
themselves
in
situations
where
existing
standards
are
unavailable
or
unsuitable
for
U.S.
government
needs.
The
technical

subcommit-
tees
have
specialized
expertise
in
various
fields,
in-
cluding
mobile,
wireless,
and
multimedia
telecom-
munications.
FederalTelecommunications System
FTS.
The
in-
tercommunications
network
used
primarily
by
U.S.
government
civilian
agencies.
It

includes
intercon-
nections
to
other
agencies
and
to
the
public
switched
telephone
network
(PSTN).
Federation
of
American
Research
Networks
FARNet.
An
organization
comprised
of
commercial
providers,
some
telephone
providers,
and

mid-level
NSFNet
networks
that
meet
to
discuss
issues
related
to
these
businesses
and
the
Internet.
Federation
of
Communications Services
FCS.
A
trade
association
representing
the
mobile
communi-
cations
industry
in
the

British
Isles.
FCS
promotes
and
encourages
a
healthy
market
environment
for
the
communications
industry
in
the
U.K.
and
represents
its
members
to
the government
and
various tele-
communications
agencies.
/>feed horn, feedhorn A
basic
signal-capturing

com-
ponent
in
satellite
receiving
antennas
that
is
mounted
at
the
focal
point.
It
must
either
be
rotated
to
corre-
spond
to
the
polarity
of
the
incoming
signal
(horizon-
tal

or
vertical)
or
be
attached
to
a
dual
coupler.
The
focal
length
of
the
feed
hom
is
dependent
on
the
depth
and
diameter
of
the
parabolic
dish
in
which
it

is
mounted.
The
feed
hom
is
attached
to
a
signal
am-
plifier.
See
antenna,
low
noise
amplifier,
microwave
antenna,
parabolic
antenna.
feedback
n.
1.
Information
or
phenomena
that
are
re-

flected
or
translated
and
returned
to
the
originating
or
transmitting
source.
2.
An
opinion
offered
in
re-
sponse
to
some
preceding
event
or
infonnation.
3.
Re-
turned
information
about
data

that
has
been
received
or
passed
through.
In
networks,
there
are
many
feed-
back
mechanisms
providing
information
data
rates,
congestion,
traffic
in
the
opposite
direction,
and
the
progress
or
success

of
a
transmission.
feedback control
FC.
A
means
of
controlling
a
sys-
tem
by
sensing
impulses
or
signals
that
are
compared
to
a
reference
or
desired
value
and
responding
accord-
ingly.

For
example,
when
humans
get
cold
and
their
body
temperatures
drop,
the
nervous
system
senses
the
difference
and
causes
the
body
to
shiver
to
help
it
generate
sufficient
heat
to

maintain
life.
In
a
tele-
phone
system,
ifa
phone
remains
off-hook
for
more
than
a
prescribed
length
of
time,
the
system
'senses'
the
anomaly
and
responds
with
a
beeping
sound

or
message
suggesting
the
subscriber
hang
up
the
phone.
In
Internet
services
using
dynamic
IP
allocation,
ifa
348
© 2003 by CRC Press LLC
connected subscriber
is
inactive
for
a certain period
of
time,
the
service
may
disconnect

the
subscriber
in
order
to
make
the
IP
number
available
to
another
sub-
scriber.
In
robotics,
feedback control
is
an
important
means
to
enable
arobot
to
sense
and
navigate
around
its

environment.
Thus,
feedback control systems
are
used
throughout
the
telecommunications industry
in
a multitude ofways
to
start,
stop,
and
maintain
sys-
tems
in
order
to
facilitate efficient operations.
See
hysteresis
device.
feedback signal
1.
A signal that loops back around
to
its
source.

An
undesirable
audio
or visual artifact
can
occur
when
the
same
signal
that
is
being trans-
mitted
travels
back
through
the
original
transmissions
media.
In
sound
systems, it commonly manifests
as
a piercing, shrieking
sound,
as
when
a microphone

is
located
too
near a speaker carrying signals
from
that
microphone.
If
carefully controlled,
audio
feed-
back
can
sometimes
be
used
to
boost a weak
signal.
In
visual
systems,
feedback often manifests
as
ghost
images
or wiggly distortions.
2.
An
intentional

diag-
nostic looped back signal.
In
diagnostic systems,
when
a
signal
is
transmitted
and
then
compared with
a reference when it returns (the returning signal
is
the
feedback signal), it
is
possible
to
evaluate
the
similarities
and
differences between
the
two
signals,
or
the
information carried

on
those
signals.
feeder cable
1.
A primary cable, extending
from
a
service provider
or
central switching location,
to
a
distribution panel
or
end-user. In
large
installations,
there
may
be
a main feeder cable
and
branch feeder
cables.
2.
The
cable
that
connects a primary distri-

bution
frame
with intermediate distribution
frames.
3.
A
main
network backbone
cable,
which
may
have
branch
feeder
cables leading
to
the
main
host
com-
puters.
4.
A
heavy
duty,
primary,
or
high
bandwidth
wire

or
cable
intended
to
carry
the
main
part
of
traf-
fic
from
the
transmission
source
to
its
primary
dropoff
points
or
hosts.
Thus,
fiber optic cables
and
25-pair
cables
are
common
feeder cables.

FEFO
first
ended,
first
out.
A priority queuing
ar-
rangement
in
which
the
first
item processed, or
the
first
process completed,
is
the
first
to
be
passed
on,
or
further
processed.
Thus,
processes
that
are

finished
are
taken
out
of
the
queue
in
order
to
leave
space
or
processing
time
for
others.
See
FIFO,
FILO,
LIFO,
LILO.
femto-
(symb.
- f)
An
SI
unit prefix
for
10-

15
, a
very,
very
small
amount.
In
decimal,
femto-
is
expressed
as
0.000 000000000001.
See
atto
FEP
See
Front
End
Processor.
FER
Frame
Error
Rate.
Fermat,
Pierrede(1601-1665)A
French
lawyer,
lin-
guist,

and
mathematician
who
made
many
contribu-
tions
to
our understanding
of
mathematics
and
op-
tics,
in
spite
of
his
recreational
approach
to
mathemat-
ics,
which
meant
that
many
of
his
discoveries

initially
went unpublished. Fermat's principle
is
named
after
him.
Fermat's
principle
When
electromagnetic radiation
travels
by
reflection offa surface
from
one
point
to
another,
it
will
take
the
path that
can
be
traversed
in
the
least amount of
time.

Fermi level Avalue designated
for
electron energy
at
half
the
Fermi
distribution
function.
Fermi,Enrico (1901-1954)
An
Italian
physicist
who
investigated atomic physics
by
systematically irradi-
ating the elements, work derived
in
part
from
the
in-
vestigations of
James
Chadwick.
ferric oxide A metallic compound commonly used
to
coat
thin tapes

or
platters used
in
magnetic stor-
age
media.
The
ferric
oxide molecules
can
be
selec-
tively rearranged
by
magnetic impulses
in
order
to
encode
the
desired information
on
the
medium.
There
are
other types
of
coatings available
for

applications
such
as
sound or
video
recording;
the
differences
in
various
coatings
can
affect
the
quality
of
the
recording.
ferroelectric liquid crystal
FLC.
Crystals that
are
incorporated into spatial light modulators
(SLMs)
in
optical computing technologies. They
have
the
ca-
pacity

for
very
fast
bipolar switching. Surface-stabi-
lized
FLCs,
created
by
suppressing
the
natural heli-
cal
structure
of
FLCs,
are
used
in
a number ofhigh-
resolution color display technologies, including
low
power microdisplays. They
are
also
suitable
for
use
in
optical shutters.
The

Ferroelectric Liquid Crystal
Materials Research Center
is
located
at
the
Univer-
sity
of
Colorado.
ferromagnetic Having the property
of
being very
easily magnetized with high hysteresis,
Le.,
magne-
tism
that changes readily with changes
in
the
mag-
netizing
force.
See
electromagnet.
ferrule A snug ring
or
cap
encircling a
tool,

pipe, or
wire;
a short length oftubing or bushing (insulating
liner)
that
helps
to
strengthen or secure ajoint
or
cou-
pling component. It
is
sometimes called a sleeve,
though
the
term
is
usually applied
to
"hard" sleeves
(as
opposed
to
soft, flexible sleeves)
made
ofsturdy
materials. It
may
include a
flange.

Ferrule Examples
Ferrules
are
the most important single component
in
fiber optic connectors. They come
in
a variety
of
shapes,
materials,
andformats. They
may
be
unflanged
(bonom
left) orflanged
with
plastic
(left)
or stainless
steel
(right),
and
they
are
commonlyfabricated
from
zirconia
(a

type
of
corrosion and heat-resistant
ce-
ramic - right), though plastic ferrules
(left)
are
now
available. Ferrules similar
to
those shown above
are
commonly incorporatedinto standardized
ST-
and
FC-
connectors.
ferrule, fiber optic
In
fiber optics cable assemblies,
a
ferrule
is
the
most important structural
member.
It
349
'··.:·a

'.·:.:·':··~·'·'·f!
.;s~~-
:~~~
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
surrounds,
secures,
and
aligns
the
fiber
filament
and
supports
the
surrounding
housing.
To
meet
the
de-
mands
of
optical
alignment
of
fiber

lightguides,
fer-
rules
must
be
exact
and
should
not
stress
or
overly
bend
the
joint,
othetwise
interference
from
imperfect
coupling
could
adversely
affect
the
angle
of
the
light
beams
or

allow
them
to
leak
at
the
joints.
Ferrules
are
commonly
made
of
zirconia
(a
ceramic
made
from
a
crystalline
powder)
or
alumina.
Zirco-
nia
is
favored
for
its
bending
strength,

resistance
to
corrosion,
hardness,
and
heat
resistance.
It
holds
up
well
in
the
polishing
process
and
over
time
once
in-
stalled.
More
recently,
plastic
and
opaque
glass-ce-
ramic
ferrules
have

been
improved
to
the
point
where
they
exhibit
acceptable
strength
and
durability
for
cost-effective
alternatives
to
zirconia
for
certain
ap-
plications
in
addition
to
which
they
may
not
require
polishing.

Commercial
ferrules
for
fiber
filaments
may
come
with
pre-domed
or
pre-angled
endfaces
to
facilitate
termination.
They
may
be
semifinished blanks
or
whole
fmished
standardized
ferrules
such
as
SC-
and
LC-
styles.

They
are
available
with
or
without
flanges.
3M
has
produced
a
line
of
connectors
that
use
a
V-
groove
rather
than
a
ferrule
for
coupling
optical
fi-
bers.
Interferometers
can

be
used
to
assess
the
char-
acteristics
of
the
ferrule-supportedjoint.
See
interfer-
ometer.
FES
Fixed
End
System.
Fessenden, Reginald Aubrey (1866-1932) A
pro-
lific,
Canadian-born,
American
inventor
and
radio
pioneer
who
was
one
of

the
fIrst
to
try
to
devise
ways
to
carry
information
on
top
ofa carrier
wave.
In
the
process
of
trying
to
achieve
this,
he
developed
a
high-
frequency
generator
in
1901

that
could
create
radio
wave,
and
a
hot-wire
barretter,
which
was
developed
into
an
electrolytic detector,
for
detecting radio
waves.
On
Christmas
Eve
1906,
to
the
astonishment
of
those
who
heard
the

broadcast,
Fessenden
suc-
ceeded
in
transmitting
voice
and
music,
using
an
Alexanderson
alternator,
over
public
radio
waves
to
the
U.S.
east
coast.
See
barretter,
carrier
wave,
elec-
trolytic
detector,
radio

history.
FEXT
See
far
end
crosstalk.
Feynman,
Richard
Phillips (1918-1988) A
charis-
matic,
individualistic
American
physicist
who
con-
tributed
greatly
to
our
understanding
of
physics,
es-
pecially
in
quantum
electrodynamics
(QED
quod

erat
demonstrandum - that which
has
to
be
demon-
strated),
who
developed
Feynman
diagrams
and
pro-
vided
insights
into
the
theory
of
computing.
FFT
See
Fourier
transform,
fast.
FGDC
See
Federal
Geographic
Data

Committee.
fiber
1.
A
strand,
filament,
or
other
structure
with
long,
slender
threadlike
qualities.
2.
Colloquial
for
fiber
optic
(or
optical
fiber).
See
fiber
optic.
fiber bundle
Two
or
more
fiber

optic
filaments
held
in
close
proximity,
either
with
a
supporting
structure
or
sheathing.
Combining
fibers
in
a
bundle
enables
more
light
signals
to
be
delivered
to
the
destination.
It
is

not
uncommon
for
hundreds
of
fiber
filaments
to
be
contained
within
a
single
bundle
as
the
indi-
vidual
filaments
are
very
small.
Why
use
many
fi-
bers
instead
ofa
fatter

fiber
(jiber
rod)?
There
are
a
Basic
Components
ofa Fiber
Optic
Cable
Bundle
filler
(no
fibers)
tension member
single
cable
assembly
fiber optic filament
Single Cable Assembly
Bundled Cable Assembly
The basic parts
of
a single multifiber cable (left)
and
a bundle
of
multifiber cables (right) containing
four

single
multifiber cables, with reflectiveiprotective sheaths (cladding)
and
outer sheaths (e.g., armoring), as needed.
350
© 2003 by CRC Press LLC
number
of
practical
advantages
to
bundling
fibers,
including
flexibility
and
the
capability
of
splitting
off
fibers
along
the
path
as
needed
as
for
communica-

tions
"drops"
(local
service),
signs,
or
ambient
light
fixtures.
The
arrangement
of
fibers
within a
bundle
is
related
to
the
purpose,
length,
size,
weight,
and
philosophy
of
the
fabricator.
Often
large

numbers
of
fibers
are
randomly
bundled
with
small
gaps
between
fibers.
The
gaps
may
be
useful
in
providing
added
flexibil-
ity
to
the
cable,
or
may
be
filled
with
filler

materials
to
provide
structural
cohesion
to
the
bundle.
Some
bundles
are
loose
along
the
running
portion of
the
bundle
but
tightly
aligned
at
the
endfaces
through
a
fusion
joint
process.
This

facilitates
coupling
and
re-
duces
the
space
needed
for
the
coupler.
Bundles
are
sometimes
carefully
aligned
for
certain
purposes,
as
in
a
single
lightline
or
an
arrayed
face-
plate
of

certain
dimensions.
Sometimes
bundles
are
deliberately
randomized
in
order
to
provide a
ran-
domly
even
light
source
at
the
point
where
the
light
exits
the
endfaces
of
the
fibers
in
the

bundle.
Sometimes
fibers
are
bundled
for
ease
of
handling
and
installation.
It
is
practical
to
bundle
many
fibers
together
and
provide extra external insulation
and
armoring
against
the
elements
in
bundles
that
are

to
be
laid
hundreds
of
feet
undetwater
in
deep
oceans.
Bundles
are
also
practical
in
situations
where
the
de-
livery ofdifferent
wavelengths
over
the
same
cable
is
desired.
See
faceplate,
lightline.

Fiber Channel
See
Fibre
Channel
Standard.
fiber creelA
device
for
spooling
fiber
optic
filaments
to
facilitate
handling.
1.
W.
Hicks
was
one
of
the
first
to
spool
optical
fiber.
See
creel.
Fiber Dispersion Measurement System

FDMS.
A
fiber
Bragg
grating
measurement
system
that
utilizes
interference
phenomena
to
evaluate
grating
transmis-
sion
properties,
developed
by
NASA.
The
system
is
quickly
able
to
fully
characterize
fiber
device

phase,
amplitude,
transmission,
and
reflection
from
either
direction.
FiberDistributedDataInterface
FDDI.
An
Ameri-
can
National
Standards
Institute
(ANSI
X3T12,
for-
merly
X3T9.5)
standard high-bandwidth
100
Mbps
packet-switched
protocol
developed
by
the
X3T9.5

committee.
FDDI
Architecture
Standard
Documents
Abbreviation Item
Notes
MAC
Media
Access
Control
A
network
control
mechanism
for
defining
fonnats
and
methods.
Like
the
PHY
layer,
the
MAC
layer
is
directly
implemented

in
FDDI
chips.
The
higher
LLC
sublayer
provides
data
to
the
MAC.
PHY
Physical
layer
An
electronic
signal
encoding/decoding
layer
which
mediates
between
the
higher
MAC
layer
and
the
lower

PMD
layer.
PMD
Physical
Medium
Dependent
The
lowest
sub
layer,
which
specifies
various
physical
media
such
as
interface
connectors,
cables,
power
sources,
photodetectors,
etc.
SMT
Station
Management
A
node
manager

and
bandwidth
allocator.
The
SMT
is
further
subdivided
into
connection
management
(CMT)
which
controls
access,
ring
management
(RMT)
which
provides
diagnostic
capabilities,
and
frame
services.
FDDI
Basic
Port
Types
Port

Type Characteristics
Mport
Master
port
Connects
two
concentrators
and
can
communicate
with
DASs
and
SASs.
Sport
Slave
port
Connects
single-attachment
devices
for
interconnecting
stations,
or
for
connecting
a
station
to
a

concentrator.
Aport
Dual-attachment
Connected
to
the
incoming
primary
ring,
and
outgoing
secondary
ring.
See
A
port
dictionary
entry.
B
port
Dual-attachment
Connected
to
the
incoming
secondary
ring
and
the
outgoing

primary
ring.
351
© 2003 by CRC Press LLC