Fiber Optics Illustrated Dictionary - Part 42 potx

Fiber
Optics
Illustrated
Dictionary
geostationary orbitA
type
of
orbit
that
is
timed
with
the
movement
of
the
body
it
is
orbiting
so
the
period
is
equal
to
the
average
rotational
period
of

the
orbited
body.
If,
in
addition,
the
orbit
is
circular,
the
satellite
will
appear
to
be
not
moving
when
viewed
from
the
ground,
hence
the
name.
In simpler
terms,
if
you

place a satellite
in
a circular
orbit
at
about
35,900
to
42,164
Ian
from
the
ground,
it
will
appear
to
remain
in
the
same
place
because
of
its
synchronized
relationship
to
the
EaIth's

orbit.
This
type
of
orbit
has
some
advantages
for
communica-
tions.
The
satellite
is
always
available
at
the
same
location
and
not
many
high
altitude satellites
are
needed
to
provide
global

coverage.
The
main
disad-
vantage
is
that
powerful
sending
and
receiving
sta-
tions
are
needed
to
send
and
receive
signals
to/from
such
a
high
orbit.
Geostationary
orbits
were
described
by

Arthur
C.
Clarke
in
the
1940s
and
1950s
in
con-
siderable
detail
and
with
remarkable
foresight.
Also
called geosynchronous orbit
and
fixed satellite
orbit.
Geostationary Orbit

In ageostationary orbit, the movement
of
the satel-
lite keeps pace with the movement
of
the Earth and is
thus within the same general visual

and
communica-
tions region at all times, as seen ji-om the Earth.
geosynchronous orbit
See
geostationary
orbit.
GEOTAIL A
Japanese
research
satellite
launched
in
1992
to
study
the
structure
and
dynamics
of
the
tail
region
of
the
Earth's
magnetosphere.
The
orbit

of
the
satellite
was
planned
so
it would cover the
magnetotail
over
a
wide
range
of distances.
It
con-
tains
instruments
to
measure
the
magnetic
field,
the
electric
field,
plasma,
energetic
patticles,
and
plasma

waves.
/>German Space Operations Center GSOc. A
com-
plex
located
near
Munich,
Germany,
that
was
origi-
nally
established
to
support
the
first
German
research
satellite
(AZUR),
launched
in
1969.
GSOC
is
a
fa-
cility of
the

German Space Missions Directorate
(DLR)
that
prepares
and
executes
national
and
inter-
national
cooperative
space
flight
projects
through
the
main
facility
and
a
number
of
remote
satellite
ground
stations.
GSOC
responsibilities
include
not

only
mis-
sion
preparation,
acquisition,
rocket
operations,
and
payload
administration,
but
also
the
development of
software
support
systems
for
mission
support,
data
handling,
and
ground
operations.
402
One
of
the
interesting experiments undertaken

by
GSOC
and
its
associates
is
the
GPS
Small
Satellite
Mission
Equator-S
(launched
in
1997).
Before
this
mission,
Global Positioning
System
(GPS)
receivers
could
be
used
only
in
near-Earth
regions,
well

below
the
orbiting height of
the
GPS
satellites
themselves.
This
experiment successfully
demonstrated
that
GPS
receivers
could
be
used
at
altitudes
up
to
34,000
ki-
lometers.
/>germania A short
name
for
germanium
oxide.
See
germanium.

germanium
Germanium
is
a
"semi-metal"
substance
discovered
in
the
I
880s.
It
is
obtained primarily
as
a byproduct of
zinc
refining.
There
are
reports
that
germanium
may
slightly convert
transverse
waves
to
longitudinal
waves

and
vice
versa.
Materials
with
conversion capabilities
are
useful
for
semiconductor
design.
The
primary
use
for
germanium
is
for
fiber
optic
sys-
tems,
and
infrared
optics
account
for
another
13±2%
of

the
market.
Germanium
chloride
(GeCI
4
)
is
one
of
the
chemicals that
may
be
used
in
modified
chemi-
cal
vapor disposition
(MCVD)
processes
for
creat-
ing
preform blanks
for
pulling
optical
fibers

.
In pioneer vapor deposition
fiber
preform
fabrication
at
Coming, germanium tetrachloride
was
used
to
form
germanium oxide.
See
fiber
fuse
effect,
va-
por
deposition.
GETS
See
Government
Emergency
Telecommuni-
cations
Service.
GFP
See
global
function

plane.
GFC
See
generic
flow
control.
GGP
See
Gateway
to
Gateway
Protocol.
ghost
I.
A
shadow
image
on
a monitor
with
phos-
phor
bum-in.
When
a
phosphor-coated
display
device
continually displays
the

same
image
(especially if
it
is
a bright
one)
an
undesirable
pale
image
that
does
not
disappear
when
the
screen
is
refreshed
may
be
burned
into
the
display surface,
thus
interfering
with
the

display ofdesired
images.
This
ghost
image
in-
dicates
permanent
damage
to
the
monitor
(unless
the
coating
is
replaced).
See
screen
saver.
2.
In audio
communications, a quieter repeat
or
echo
of a
con-
versation.
3.
In optics, a light-caused

image
in
the
dispersion
plane
resulting
from
periodic
ruling
errors
in
a
diffraction
grating
(as
opposed
to
scattering
errors).
ghost, broadcast
In
broadcast
images
on
a
television
screen,
a slightly
offset,
pale

copy
of
the
desired
im-
age
caused
by
secondary transmission of
the
origi-
nal
signal.
Terrain
can
cause
reflections of
the
direct
signal
that
arrive
at
the
receiver just slightly delayed
and
make
the
image
appear

slightly
blurred
or
double.
ghost port
In
the
early
days
of
computing,
software
was
in
its
development stages
and
was
not
always
written
to
handle
processes
in
a
secure
manner.
Thus,
when

users
left a
system
or
terminated a
remote
con-
nection
in
an
unexpected
way,
the
process itself
did
not
necessarily terminate, allowing
the
next
user
into
the
currently
open
account
or
process.
It
would
some-

times
allow
timeshare users,
for
example,
to
log
in
to
the
previous user's account
through
the
ghost
port
(the
unterminated
session)
and
access
the
files.
© 2003 by CRC Press LLC
Ghost
ports
are
less
common
now,
with

standard
op-
erating
systems
and
more
security-savvy
program-
mers
developing
the
software,
but
hackers
are
still
sometimes
aware
of
security
holes
and
programs
and
methods
that
create
ghost
port
access

to
less
robust
systems.
The
phrase
can
also
refer
to
an
access
port
to
a
computer
system
that
is
visible
to
technical
us-
ers
but
invisible
to
nontechnical
users,
in

other
words,
one
accessible
through
system
commands
or
proce-
dures
that
are
inherent
to
the
system
(as
opposed
to
being hacked into
the
system) but not generally
known
outside
of
techie
circles.
Thus,
ghost
port

re-
fers
to
a
port
that
is
left
behind
and
is
mistakenly
as-
sumed
to
be
a
new
port
or
one
that
is
visible
or
ap-
parent
only
to
a

subset
of
computer
users.
Ghostscript APostScript
graphics
language
that
is
part
of
the
Free
Software
Foundation's
GNU
project.
Ghostscript
is
almost
fully
compatible
with
Adobe's
PostScript.
Ghostscript
is
a
great
tool

for
viewing
and
printing
PostScript
files.
Adobe
PDF
readers,
freely
available
on
the
Internet,
are
now
beginning
to
su-
persede
the
use
of
Ghost
script
for
viewing
and
print-
ing

PostScript
files
on
some
systems,
but
enhance-
ments
to
Ghostscript
for
PDF
compatibility
have
kept
it
alive
on
others.
giant magnetoresistance
GMR.
Aresistance
effect
discovered
in
the
late
1980s
by
P.

Gruenberg
in
Ger-
many
andA.
Fert
in
France.
Large
resistance
changes
were
observed
in
materials
comprised
of
alternating,
very
thin
layers
of
metallic
elements
when
exposed
to
high
magnetic
fields

at
low
temperatures.
Other
scientists
were
excited
by
this
discovery
and
began
to
study
many
different
types
of
materials
and
con-
figurations
of
layers
to
better
understand
the
effect
and

to
see
whether
it
could
be
produced
without
sub-
jecting
the
materials
to
very
low
temperatures.
ffiM
researchers
such
as
S.
Parkin
took
aparticular
inter-
est
in
this
area
of

research.
It
was
determined
that
very
thin
combinations
of
nonmagnetic
metals
between
layers
of
magnetic
metals
could
induce
the
nonmag-
netic
layer
to
change
its
orientation.
Oscillations
in
the
magnetic

alignment
were
also
detected,
and
it
was
noted
that
resistance
was
low
or
high
depending
upon
whether
the
layers
were
in
parallel
or
antiparallel
ar-
rangement.
GMR
research
has
led

to
a
new
category
of
super-
sensitive
hard
disk
drives
and,
since
this
is
a
general
reproducible
effect,
no
doubt
many
other
practical
applications
will
be
developed.
See
Kerr
magneto-

optic
effect.
.gif
The
conventional
graphics
file
name
extension
used
for
CompuServe's
proprietary
Graphics
Inter-
change
Format
(GIF)
raster-format
graphics
files.
See
Graphics
Interchange
Format.
giga-
(abbrev.
- G
when
combined)

(pron.
jig-a) A
prefix
for
10
9
or
1,000,000,000
in
the
SI
system.
One
billion.
In
computing,
a
giga
is
2
30
or
1,073,741,824
(a
multiple
of
1024).
Giga-
has
long

been
used
in
supercomputing,
mainframe,
and
scientific
applica-
tions,
but
it
was
relatively
unknown
in
lay
language
until
the
mid-1990s
when
gigabyte (Gbyte) hard
drives
dropped
to
consumer
price
ranges.
It
used

to
be
a
lot
of
storage
space.
Ten
megabytes
used
to
be
a
lot
of
storage.
In
fact,
whole
community
BBS
sys-
tems
used
to
run
on
five
megabyte
drives

in
the
early
1980s.
Now
two
gigabyte
drives
are
considered
to
be
average.
See
atto
gigabit
GB.
(pron.
jig-a-bit)
1,073,741,824
(2
30
)
bits.
Gigabit Ethernet
GbE.
Ethernet
networking
capa-
bilities

capable
of supporting half
and
full
duplex
transmissions
at
speeds
of 1
Gbps
(one
billion
bits
per
second).
Fast
Ethernet,
the
predecessor
to
Giga-
bit
Ethernet,
is
a
widely
installed
international
open
standard.

In
1997,
the
IEEE
approved
the
P802.3ab
study
group's
proposed
1
OOOBase-
T
standard
for
full
duplex
Gigabit
Ethernet
signaling
over
Category
5
networking
systems.
This
approval
led
to
the

IEEE
802.3z
Working
Group
ratifying a
standard
for
Gi-
gabit Ethernet,
in
June
1998,
that included three
physical
layer
specifications
(one
for
shielded
cop-
per
wire,
two
for
optical
fibers).
Gigabit
Ethernet
was
developed

because
vendors
and
users
wanted
the
benefits
ofa
scalable
high
speed
net-
work
to
support
existing
Ethernet
frame
and
proto-
col
characteristics
to
enhance
rather
than
obsolete
existing systems. Gigabit Ethernet uses
the
same

frame
format,
media
access
control,
and
flow
con-
trol
characteristics
as
slower
Ethernets.
Gigabit
Eth-
ernet
provides
a practical
way
to
set
up
a
backbone
for
interconnecting
Ethernet
and
Fast
Ethernet

net-
works,
and
provides
an
Ethernet
upgrade
path
as
the
technology
becomes
cheaper.
The
types
of
applica-
tions
that
require
enhanced
Ethernet
implementations
include
scientific
modeling,
multimedia
communica-
tions,
data

warehouse
search
and
retrieval,
and
oth-
ers.
The
most
significant
competitor
to
the
faster
ver-
sions of Ethernet
is
asynchronous transfer
mode
(ATM).
Gigabit Ethernet
is
implemented
at
the
physical
(PHY)
and
media
access

control
(MAC)
layers.
It
supports
the
same
frame
format
and
size,
and
carrier
sense multiple access with collision detection
COSMA/CD)
as
Ethernet,
and
Fast
Ethernet.
Quality
of
service
(QoS)
is
not
inherent
in
Gigabit
Ethernet,

which
is
primarily a
high
speed
connectivity
mecha-
nism,
but
is
incorporated
through
other
standards.
RSVP
is
one
way
ofproviding quality
through
an
open
standard
that
can
be
incorporated
into
a
Giga-

bit
Ethernet
system.
Objectives
for
link
distances
include
multimode
fi-
ber
optic
links
up
to
550
meters,
single-mode
fiber
optic
links
up
to
3
kilometers,
and
copper-based
links
up
to

25
meters,
and
Category
5
unshielded
twisted
pair
(UTP)
links
up
to
100
meters.
A
Gigabit
Media
Independent
Interface
(GMII)
is
also
being
studied.
See
asynchronous
transfer
mode,
Ethernet,
Fast

Eth-
ernet,
Gigabit
Ethernet
Alliance.
GigabitEthernetAlliance
GEA.
A
California-based
multivendor
open
forum
established
in
1996
to
pro-
mote
the
development
and
acceptance ofGigabit
Ethernet
technology
and
to
actively
support
and
ac-

celerate
the
standards process.
The
GEA
supports
IEEE
activities
with
regard
to
the
development
and
ratification ofEthernet standards, particularly
the
403
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
High-Speed
Study
Group,
the
IEEE
802.3
Working
Group,

and
the
IEEE
802.3z Gigabit Ethernet task
force.
The
group
provides technical resources
for
implementation
and
product interoperability.
In
June
1998,
it
ratified a standard
for
Gigabit Ethernet.
See
Gigabit
Ethernet.
l
Gigabit Interface Connector
GBIC.
An interface,
commonly
sold
as
ahub-compatible peripheral

card,
used
in
Gigabit
Ethernet uplinks. A
hub
may
have
slots
for
more
than
one
GBIC.
The
GBIC
enables
an
optical
cable
to
be
connected
to
an
appropriate port
by
converting
electrical impulses
into

laser light
sig-
nals
for
transmission over a
medium
such
as
Fibre
Channel.
It
is
sometimes
also
called a Gigabit Inter-
face
Converter.
See
Gigabit Ethernet.
Standardized Cabling Specifications
Specification Description
1000BASE-CX
Wire-based
transceivers
or
physical
layer
(PRY)
devices
for

short-haul
shielded
copper
cable
connections
up
to
25
meters.
1
OOOBASE-
T
Wire-based
transceivers
of
physical
layer
(PRY)
devices
for
four-pair
twisted-pair
copper
cable
connections
up
to
100
meters.
1000BASE-8X

Optical
transceivers
or
physical
layer
(PRY)
devices
for
cabling
through
optical
fibers
at
770
to
860
nanometer
wavelengths.
Based
upon
Fibre
Channel
signaling
for
multimode
fiber.
1
OOOBASE-
LX
Optical

transceivers
or
physical
layer
(pRY)
devices
for
cabling
through
optical
fibers
at
1270
to
1355
nanometers.
Based
upon
Fibre
Channel
signaling
for
single-mode
or
multimode
fiber.
1000BASE-LH
Long-haul
multivendor
specification.

Gigabit
News
Industry
news
on
ATM/Gigabit
net-
works
along
with
analysis
of
competing
technologies
and
market
trends,
published monthly
by
Infonna-
tion
Gatekeepers,
Inc.
gigabyte
GByte,
GB.
(pron.jig-a-bite)
1,073,741,824
(10
9

)
bytes.
Data
rates
are
often described
in
giga-
bi
ts
per
second
(Gbps)
or,
for
very
fast
rates,
may
be
described
as
Gigabytes
per seond
(GBps).
Gigabytes
are
also
used
to

describe
the
storage
capacities
of
a
large
number
of
tape
and
hard
drive
storage
media.
Gigabyte System Network
GSN.
See
Hippi-6400.
GIGAMOAgigabyte-class magneto-optical
storage
technology
developed
by
Fujitsu Limited
and
Sony
Corporation,
announced
in

November
1998.
It
was
404
the
first widely available magnetic-induced super
resolution
(MSR)
technology,
providing
1.3
GBytes
of
storage
on
a 3.5-inch
disc
with a
5.92
MBytes
per
second transfer
rate.
GIGAMO
retains the
same
car-
tridge
size

and
disc
diameter
as
ISO/IEC
15041
stan-
dards
but
has
higher linearbit
densities.
The
data
stor-
age
capacity
is
about
twice
that
of
the
widely
adopted
640-MByte
CD-ROM
discs,
and
the

technology
is
backwardly compatible, using
the
same
write
heads
as
earlier systems.
See
magnetic super resolution.
GIGO garbage
in,
garbage
out.
An abbreviation
to
describe a situation
in
which output cannot
be
better
than
its
corresponding
input,
with
the
implication
that

it
is
the
fault
and
responsibility of
the
developer
or
data
entry person
if
the
system
gives
back
bad
or
in-
complete information.
See
garbage
in/garbage
out.
Gll
See
global information infrastructure.
gilbert A centimeter-gram-second (CGS) unit
of
magnetomotive

force
equal
to
10
divided
by
4p
am-
pere-tum.
It
is
named
after
William
Gilbert.
Gilbert,William (1544-1603)
An
English
physicist
and
physician
who
investigated electrostatic charges
in
various substances.
He
observed that magnetized
iron
lost its attractive power
when

heated
to
red
heat
and
published
De
magnete
(On
the
magnet)
in
1600.
He
emphasized
the
distinctions
between
the
magnetic
effect
of
substances, such
as
lodestone,
and
the
at-
tractive properties of
amber,

adistinction previously
promoted
by
1.
Cardan
in
1550
but
at
the
time
still
not
widely considered.
In
his
treatise,
he
used
the
word
electrica
to
describe
attractive
phenomena.
Gil-
bert established that
the
Earth

is
a
large
magnet,
thus
explaining
the
general behavior of
compass
needles.
The
gilbert unit
of
magnetomotive
force
is
named
after
him.
See
gilbert, versorium.
GILC
See
Global Internet Liberty
Campaign.
Gilder's law
Bandwidth
capacity
will
roughly

double
in
capacity every
six
or
nine
months
or
so.
This
law,
in
a sense,
takes
over
from
Moore's
law,
with
chip
processing capacities doubling about every
18
months
to
two
years.
With
the
emphasis
away

from
single user systems
towards
network technologies,
the
same
general
idea
is
being
applied
to
the
growth
and
evolution
of
network transmission technologies.
The
term
is
attributed
to
Greg
Papadopoulos
at
Sun
Microsystems
in
honor

of
George
Gilder,
a business
technology commentator
and
strong proponent
of
optical network technologies.
See
lambda
switching,
Moore's
law.
Gill,
Jonathan
"Jock"
(ca.
1946- )
In
1992,
Gill
served
as
a Clinton/Gore campaign consultant
on
electronic publishing
and
email
access

and
became
the
Director
of
Special
Projects
in
the
Office
of
Me-
dia
Affairs
from
1993
to
1995,
during
the
Clinton
Presidential Administration.
He
is
probably best
known
for
developing
email
access

to
White
House
documents
and,
in
1994,
being
the
first
manager
of
the
U.S.
President's
Web
site,
allowing
users
to
take
a virtual tour
of
the
White
House
and
find
informa-
tion

on
contacting government
agencies.
Gill
is
the
founder
of
Penfield
Gill,
Inc.,
a
media
communica-
tions
and
planning
company.
© 2003 by CRC Press LLC
GILS
See
Government
Information
Locator
Service.
gimbal A
mechanism
or
material
that

permits
an
at-
tachment
to
be
freely
suspended
or
inclined
in
such
a
way
that
the
suspended
attachment
remains
level,
or
so
the
attachment
can
be
inclined
in
any
direction

or
several
directions.
Marine
compasses
and
gyro-
scopes
incorporate
gimbal
mechanisms.
gimp
Extremely
flexible
wire
or
cable.
Wire
that
can
be
easily threaded, woven, or spiraled.
Gimp
is
wound
up
and
attached
to
telephone

handsets
to
al-
Iowa
length
of
wire
to
tighten
up
like
a
spring
when
not
in
use,
so
the
conversant
doesn't
have
to
inter-
rupt
the
phone
conversation
to
reach

the
refrigerator.
Gintl, Julius Wilhelm (1804-1883)
An
Austrian
physicist
and
telegraph
director
who
was
one
of
the
first
to
propose
a practical
means
to
transmit
tele-
graphic
communications
in
both
directions
at
the
same

time.
Up
to
this
time,
telegraphs
were
one
way,
thus
tieing
up
the
lines
for
returning
messages
until
the
current
message
was
finished.
Using
two
batter-
ies
and
a
compensation

method,
Gintl
devised
two-
way
communications
in
1853.
Two-way
or
duplex
te-
legraphy
was
an
important
means
of
increasing
line
capacity
that
was
later
refined
and
extended
by
other
inventors.

See
duplex
telegraphy.
Ginzton, Edward Leonard (1915-1998) A
Ukrai-
nian-bornArnerican
inventor
and
professor
who
emi-
grated
to
San
Francisco
in
1929,
Ginzton
headed
up
the
Microwave
Laboratory
at
Stanford.
He
developed
further applications
with
the

Klystron technology
developed
by
the
Varian
brothers,
the
co-founders
with
Ginzton
of
Varian
Associates,
in
1948.
In
the
late
1950s,
he
headed
up
the
Stanford
linear
accelerator
project.
In
1959,
he

became
the
CEO
of
Varian
As-
sociates,
remaining
as
Chairman
until
1984
and
serv-
ing
on
the
Board
until
1992.
Ginzton
is
remembered
not
only
for
his
technical
achievements
with

the
Klystron
tube
and
Stanford
linear
accelerator,
but
also
for
his
pioneering
man-
agement
policies.
Ginzton
was
instrumental
in
estab-
lishing
employee
incentives
and
benefits
long
before
such
practices
were

common
or
mandatory.
His
poli-
cies
aided
him
in
attracting
top
talent
to
the
firm
and
provided
a
new
model
for
employee
relations
in
the
emerging
Silicon
Valley
community.
He

also
chaired
the
National
Academy
of
Sciences
committee
that
advised
on
the
Clean
Air
Act
of
1971
and,
with
David
Packard, supported
the
development of minority-
owned
businesses.
Ginzton
has
been recognized through numerous
awards,
including

the
IEEE
1969
Medal
of
Honor
and
induction
into
the
1995
Silicon
Valley
Engineering
Council's
Hall
of
Fame.
When
the
Microwave
Labo-
ratory
at
Stanford
University broadened
in
focus,
around
1970,

it
began
to
be
called
the
E.L.
Ginzton
Laboratory.
It
is
an
independent
lab
for
engineering
and
physics
research.
See
Klystron,
magnetron,
Sili-
con
Valley,
Varian
Associates.
Giorgi System A
system
of

measurement
in
which
the
units
are
meter,
kilogram,
second,
and
ampere
(MKSA).
GIP
See
Global
Intemet
Project.
GIS
See
geographic
information
system.
Gisborne, Frederic Newton (1824-1892) An
En-
glish-born
Canadian
inventor
who
devised
new

ways
of
insulating
communications
cables
against
harsh
en-
vironments.
With
the
financial
backing
of
Americans,
most
notably
Cyrus
Field, Gisborne
was
a strong
motivational
and
administrative
force
in
linking
Eu-
rope
and

North
America,
in
1858,
with
the
first
suc-
cessful
transatlantic
telegraph
cable
and
the
first
suc-
cessful
permanent
cable
a
few
years
later.
Leading
up
to
this
important
historical
achievement,

Gisbome
studied
telegraphy
in
Quebec
in
the
1840s,
excelling
in
his
courses
and
subsequently
accepting
&~~:~:;~;:;~!~~~~J~:~~;£~t~J~~
••
(BNAETA)
and,
on
its
behalf,
negotiated
unsuccess-
fully
with
eastern
Canadian
governments
to

set
up
a
Halifax-to-Quebec telegraph line. Thereafter,
Gisbome
took
the
position
of
superintendent
of
the
N
ova
Scotian
telegraph
lines.
He
sought
backing
from
the
government
for
an
underwater
line
from
Halifax
to

Newfoundland,
expressing
an
interest
in
solving
the
problems
associated
with
undersea installation
and
maintenance.
In
1851,
the
Nova
Scotia
Electric
Telegraph
Company
was
established
to
oversee
ex-
isting
lines
and
create

new
ones.
In
1852,
Gisbome
left
his
position
with
the
Nova
Scotia
Electric
Telegraph
Company
to
establish
the
Newfoundland
Electric
Telegraph
Company.
His
as-
sociation
with
financier
Cyrus
Field
began

in
1854
when
Gisborne
contacted
Cyrus'
brother,
Matthew
D.
Field,
on
behalfof
the
financially
stressed
Newfound-
land
telegraph
project.
The
American
collaborators
purchased
the
assets
of
the
Newfoundland
Electric
Telegraph

Company
and
settled
its
debts,
traveling
the
difficult
wilderness
journey
to
St.
Johns,
New-
foundland
in
spring
1854,
to
present
the
charter
for
a
proposed
New
York,
Newfoundland,
and
London

Telegraph
Company.
The
first
undertaking of
the
ex-
panded venture
was
to
link Newfoundland with
neighboring
regions
and
with
the
U.S.
Thus,
subma-
rine
cables
were
installed
between
Cape
Breton,
New-
foundland,
and
Prince

Edward
Island,
and
telegraph
lines
were
installed
across
the
perilous Gulf
of
St.
Lawrence
(though
not
on
the
first
try).
With
the
involvement
of
the
U.S.
collaborators,
who
envisioned
oceanic
telegraphy,

Gisbome's
ambitions
increased.
He
became
determined
to
establish
a
cable
between Canada
and
Ireland. Despite months
of
harrowing
travel
and
political
arrangements
further
aggravated
by
financial
difficulties,
Gisbome
contin-
ued
to
pursue
his

goal
ofestablishing a
transatlantic
cable.
Gisbome's contribution
is
sometimes
over-
looked,
as
he
pulled
out
of
the
partnership
near
its
successful
completion,
due
to
distrust
and
disagree-
ments
with
his
collaborators,
but

he
was
an
impor-
tant
contributor,
both
to
the
inception
and
progress
of
the
project.
See
Field,
Cyrus
West;
Gooch,
Daniel;
gutta-percha;
transatlantic
cable.
GITS
Government Information Technology
Ser-
vices.
405
© 2003 by CRC Press LLC

Fiber
Optics
Illustrated
Dictionary
Gladstone-Dale law
The
refractive index ofa
sub-
stance
varies
with
a
change
in
temperature
or
volume
according
to
a
formula
in
which
the
index
of
refrac-
tion
(n)
plus

one,
over
the
density
(r),
equals
a
con-
stant
(k).
glassA
strong,
brittle
substance
primarily
composed
of
silica,
that
ranges
from
transparent
to
opaque,
de-
pending
upon
the
quantity
and

composition ofother
materials
contained
within
the
material.
Impurities
can
affect
the
color,
opacity,
polarizing
and
transmit-
tance
characteristics,
index
ofrefraction, strength,
flexibility
and
other
properties of
glass.
The
glass
in
jars
and
windows

typically
contains
about
75%
silica
combined
with
a
number
of
oxides
to
enhance
the
fabrication
properties
of
the
glass.
Pure
glass
is
generally
preferred
for
fiber
optics
com-
munications
components

(e.g.,
the
conducting
core),
but
impurities
may
be
"doped"
into
the
fiber
to
alter
its
refractive
index
or
selective transmittance of
cer-
tain
wavelengths.
There
are
special
challenges
asso-
ciated
with
pulling

out
long
filaments
ofpure
glass.
F
or
example,
the
process
itself
may
introduce
bubbles
or
a crystalline structure within the glass, which
would
interfere
with
light
transmission.
The
addition
of
oxides
to
enhance
the
fluidity of
the

glass
is
not
practical
because
it
introduces
undesired
impurities.
It
has
been
discovered
that
pulling
fibers
or
fiber
pre-
forms
at
0
gravity
results
in
a
fine,
pure
glass
with-

out
the
problems
of crystallization associated with
Earth-based fabrication.
See
pulling fiber, vapor
deposition.
glass house
colloq.
A
term
to
describe the large,
glassed-in, controlled environments used
to
house
and
protect
(and
in
some
cases
air-condition)
large
computer
installations.
These
environments still
ex-

ist,
to
some
extent,
in
supercomputing
systems,
but
technological
advances
have
decreased
the
size
and
fragility
of
many
computers,
and
glass
houses
are
no
longer
needed
for
small-
or
medium-sized

comput-
ing
systems.
Glass
houses
or
clean
houses
are
still
used
in
chip
manufacturing
environments
to
provide
a
carefully
regulated
environment
where
temperature,
humidity,
and
even
tiny
particles
can
affect

the
struc-
ture
and
functioning
ofcertain delicate
or
micromin-
iature
components.
glass
insulatorA
historic
utility
pole
insulating
safety
device
ranging
in
size
from
about
6
inches
to
about
18
inches
that

was
very
commonly
used
to
support
live
wires
on
utility
poles.
See
insulator,
utility
pole
for
a
chart
and
more
detailed
information.
glitch
1.
Unexpected,
small,
but
annoying
problem,
usually

causing
a
delay
or
minor
informational
error.
This
term
is
usually
applied
in
instances
where
rep-
etition
of
the
problem
is
unlikely
or
infrequent.
2.
Un-
desirable brief surge
or
interruption
of

electrical
power.
GlobalArea Coverage
GAC.
One
of
the
sample
data
set
archives
of
the
National
Oceanic
and
Atmospheric
Administration
(NOAA)
derived
from
the
Advanced
Very
High
Resolution
Radiometer
(AVHRR)
sensors
onboard

TIROS
and
NOAA-x satellites.
As
the
sat-
ellites
orbit,
they
collect
Local
Area
Coverage
data,
406
which
is
stored, combined,
and
compressed into
GAC,
available
for
download.
In
order
to
compress
the
data

from
LAC
to
GAC
lev-
els,
four
pixels
in
a scanline
are
sampled
and
aver-
aged
and
the
fifth pixel
is
skipped,
with
the
process
repeating
to
the
end of
the
scanline.
The

following
two
scanlines
are
then
skipped,
thus
creating a
pat-
tern
for
each
three
scanlines
on
through
the
data
file.
GAC
resolution
is
approximately
7.6
km.
Various
agencies
distribute
data
products

based
on
GAC
downloads.
For
example,
the
SeaWiFS
GAC
Level 1 consists
of
radiance data
from
combined
north-to-south
scan
swaths
with
file
sizes
of
about
19
MBytes.
Sea
WiFS
GAC
Level
2
is

taken
from
Level
1A
data
that
has
been
further
processed, calibrated,
and corrected. Unusual conditions
may
also
be
marked
within
the
data.
The
National
Science
Foun-
dation,
the
Office of
Naval
Research,
and
other
or-

ganizations
have
provided support
to
a
number
of
research
and
educational associations
for
GAC
data.
See
Advanced
Very
High
Resolution
Radiometer.
global area network
GAN.
A
network
that
is
acces-
sible
to
most
or

all
nations
in
the
world.
The
Internet
is
the
closest
thing
we
have
to
a
GAN,
although
it
is
not yet ubiquitous
or
accessible
by
all nations or
people.
Global Atmospheric Research Program
GARP.
A
program
in

the
1970s
to
study
atmospheric
trends
and
patterns
and
to
extend
the
range
of
daily
weather
fore-
casts
over
a longer period
than
was
previously
pos-
sible. The GARP Atlantic Tropical Experiment
(GATE)
was
the
first
major

experiment
in
the
GARP,
carried
out
in
1974.
GATE
is
ofinterest,
not
only
be-
cause
it
was
international
in
scope,
but
because
it
in-
volved
intercommunication
among
a
host
of

research
ships,
aircraft,
and
communications
buoys.
In
the
late
1970s
and
early
1980s,
NOAA
meteorological
satel-
Iites were designed and launched
to
support
the
GARP.
NOAA-7,
for
example,
launched
in
1981,
had
sensors
for

measuring
the
Earth's
atmosphere,
sur-
face,
and
cloud patterns.
The
GOES
system
of
sens-
ing
satellites
also
form
part of
the
GARP.
See
GOES.
GlobalAtmosphereWatch
GAW.
A
United.Nations
Commission
for
Atmospheric
Sciences

monitoring
and
assessment
program
that
uses
technology
to
track
pollution, ozone,
and
other aspects of atmosphere
composition around
the
world.
Global Business Communications
Systems
GBCS.
An
AT&T
business, which
was
rolled
in
with
the
AT
&T
Laboratory restructuring of
Bell

Laboratories
in
1995-1996, along with the Network Systems
Group,
AT&T
Paradyne,
Microelectronics,
and
Con-
sumer Products.
GBCS
is
moving
into
the
area of
multimedia
and
secure
telecommunications
selVices.
Products
include a Unix-based
selVer
that
works
on
a private branch
exchange
(PBX)

to
provide
video-
conferencing capabilities
over
data
networks
such
as
Ethernet
and
mM
Token-Ring.
The
selVer
software
is
called Multimedia Communication Etchange
(MMCX)
and
was
implemented first
on
Unix
sta-
tions,
with
the
intention ofporting
it

to
PC
operating
systems.
© 2003 by CRC Press LLC
Global ChangeMasterDirectory
GCMD.
ANASA
multidisciplinary
database
project
originating
from
the
Goddard
Space
Flight Center
(GSFC)
Global
Change
Data
Center.
The
GCMD
includes
both
na-
tional
and
international

remote-sensing
data
sets
con-
tributed
by
more
than
800
U.S.
and
worldwide
orga-
nizations, including
NOAA,
NASA,
DOE,
NSF,
EPA,
USGS,
educational
institutions,
and
others.
It
is
of
interest
to
anyone

interested
in
planet
change,
particularly
climatic
change.
The
data
includes
tem-
poral
and
geographic
information
and
some
parts
are
interlinked
with
relevant
external
information.
The
GCMD
relational
database
is
now

searchable
online
through
the
GCMD
Web
site.
The
data
is
ofparticu-
lar
interest
to
climatologists,
agriculturalists,
hydrog-
raphers,
mineralogists,
and
others.
/>Global Data Processing System
GDPS.
A
system
of
preparing
and
disseminating
cost-effective

meteor-
ological
analyses
and
forecasts.
The
GDPS
retrieves,
assesses;
decodes,
sorts,
and
analyzes
the
data
in
pre-
paring
for
making
it
available
for
distribution.
GDPS
is
one
of
three
integrated

core
components
of
the
World
Weather
Watch
(WWW)
system.
It
is
ad-
ministrated
by
the
World
Meteorological
Organiza-
tion.
GDPS
data
are
valuable
for
weather
forecast-
ing
and
meteorologically
related

agriculture,
clima-
tology,
and
aeronautics
industries.
See
Global
Ob-
serving
System,
Global
Telecommunication
System.
web/www/DPS/gdps.html
Global Development
Gateway
GOG.
A major
World
Bank
initiative proposed
through
the
GOG
Principles
discussion
forum
hosted
by

Bellanet.
The
GDG
is
sponsored
by
the
World
Bank
to
promote
in-
formation
exchange,
access,
and
development.
global directoryAn
internetwork
computer
database
that
stores
various
types
of
information
related
to
the

various
networks.
The
information
may
be
user
login
names
and
passwords,
shared database resources,
group
member
lists,
device
directories
that
can
be
ac-
cessed
by
more
than
one
network,
or
pointers
to

vari-
ous
applications
or
documents
common
to
the
vari-
ous
networks.
The
Internet
has
a
number
of
global
directories
of
file
databases,
archives,
etc.
See
Go-
pher,
Archie,
Veronica.
GlobalEnvironmentalMonitoringSystem

GEMS.
Administrated
by
the
United
Nations
Environment
Programme
(UNEP),
GEMS
was
established
as
part
of
the
Earthwatch
program
in
1975
to
support
and
strengthen
environmental
monitoring
in
participating
countries
and

to
improve
the
collection
and
evalua-
tion
of
environmental
data.
Computer-acquired
and
-processed
infonnation
is
an
important
part
of
this
effort.
See
Global
Resource
Information
Database.
global function plane
GFP.
An
architecture

within
which
the
modular
functionality
for
Intelligent N
et-
work
(IN)
services
may
be
globally
constructed.
The
GFP
functions
are
described
as
service-independent
building
blocks
(SIBs).
The
IN
is
viewed
as

a
single
entity within
the
GFP.
GFP
is
defined
in
ITU-
T
Q.1201
which
describes
a
generic
IN
GFP
model,
service-independent
building
blocks,
and
services
and
features
offered
through
a
global

service
logic.
Global Incident Analysis Center
GIAC.
A
SANS
Institute
center
that
creates
and
disseminates
reports
of
malicious
activity
on
the
Internet
submitted
by
system
administrators
and
network
security
profes-
sionals
worldwide.
GIAC

maintains
a
large
archive
of
security-related
papers
available
for
free
download.
/>global informationinfrastructure
GIL
A
term
used
since
the
mid-1990s
by
international
standards
com-
mittees
with
regard
to
goals,
standardization,
and

de-
velopment
of
global
interconnected
telecommunica-
tions
systems,
including
the
technology,
applications,
and
related
services.
Global Information Infrastructure Commission
GIIC.
An
independent,
nongovernmental
initiative
inaugurated
in
July
1995
to
promote
leadership
in
the

private
sector
and
cooperation
between
private
and
public
sectors
in
developing
information
selVices
and
networks.
GIIC
fosters
economic
growth,
education,
and
quality
of
life
through
activities
such
l
as
devel-

oping
an
accessible
and
diversified
global
informa-
tion
infrastructure.
The
GIIC
operates
as
a
project
of
the
Center
for
Strategic
and
International
Studies
(CSIS).
CSIS
is
a U.S based private organization
founded
in
1962

to
conduct
research
in
global
public
policy.
/> />GlobalInternetLibertyCampaign.A
human
rights
group
that includes
the
American Civil Liberties
Union
(ACLD),
the
Electronic
Freedom
Foundation
(EFF),
and
other
member
organizations.
Global Internet Project
GIP.
Aprivate
sector
orga-

nization
founded
in
1996,
consisting of
senior
level
managers
representing
global
software
and
telecom-
munications
industries
with
high
stakes
in
Internet
development.
As
part
of
its
activities,
GIP
encourages
the
education

of
world
decision-makers
in
the
poten-
tial
evolution
and
uses
of
the
Internet.
/>Global
Land
Information System
GLIS.
An
inter-
active
database
system
developed
by
the
U.S.
Geo-
logical
Survey
(USGS).

It
provides
data
that
is
valu-
able
in
the
study
of
the
Earth's
land
surfaces.
Samples
and
information
about
GLIS
products
are
available
online.
Topics
within
the
GLIS
database
include

cli-
mate,
geology,
hydrology,
land
cover,
and
others.
There
are
aerial
photographs,
satellite
images,
and
digital
line
graphs
to
serve
a variety of
needs.
The
aerial
photographs,
for
example,
include
sources
such

as
the
National
Aerial
Photography
Program,
Na-
tional
High
Altitude
Photography,
and
various
radar
systems.
/>Global
Maritime
Distress
and
Safety System
GMDSS.
A
maritime
safety
system
which
incorpo-
rates
automated
distress

calls
using
Digital
Selective
Calling
(DSC).
In
the
late
1970s,
maritime
experts
began
to
develop
systems
for
updating
safety
and
dis-
tress
communications,
resulting
in
the
1979
draft
of
the

International
Convention
on
Maritime
Search
and
Rescue.
GMDSS
advocates
a
global
search
and
res-
cue
plan
and
a
Global
Maritime
Distress
and
Safety
407
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
System

(GMDSS)
as
a communications infrastruc-
ture
for
the
overall
plan.
The
system
is
based
upon
a
combination
of
Earth-based
and
satellite-based
radio
services,
emphasizing
ship-to-shore
marine
signaling
through
relatively user-friendly consoles.
GMDSS
signaling
is

quickly superseding
the
decades-old
Morse
code-based
system.
In
addition
to
the
automa-
tion
of distress signals,
it
calls
for
the
shipboard
downloading
of
maritime
safety
information
as
a
pre-
ventive
measure.
In
1996,

the
Telecommunications
Act
was
written
to
encompass
U.S.
marine
vessels,
and
ships
were
re-
quired
to
install
GMDSS
equipment
by
I
Feb.
1999.
All
vessels
subject
to
Chapter
IV
of

the
Safety
ofLife
at
Sea (SLOAS) convention must
be
fitted
with
GMDSS
equipment
(with
stipulated exceptions)
as
must
mobile
offshore
drilling
units
(MODUs).
Implementation of
GMDSS
has
not
been
without
problems.
It
has
been
criticized

for
false
alarms
and
general
reliability
problems,
and
many
nations
have
been slow
to
adopt the system. See COSPAS/
SARSAT,
NAVTEX.
global mobile personal communications services
GMPCS.
A
phrase
coined
by
the
ITU-
T to describe
mobile communications through
low
Earth orbit
(LEO)
satellite

systems
but
later
broadened
to
include
other
modes
of
mobile
communications (geostation-
ary
FSS,
MSS,
"Little
LEOs"
and
wideband
LEOs).
GMPCS
was
the
discussion
theme
of
the
World
Tele-
communication
Policy

Forum
(WTPF),
resulting
in
a
set
of principles
and
recommendations
described
in
the
"WTAC
Report
to
the
Secretary-General [of
the
ITU-T]
on
GMPCS,"
January
1996.
Global Navigation Satellite System
GLONASS,
GNSS.
A satellite
system
deployed
by

the
Russian
Federation
defense
department,
which
has
much
in
common
with
the
American
Global
Positioning
Ser-
vice
(GPS)
in
terms
of satellite placement
and
the
types
of
information
transmitted.
The
24
GLONASS

system
satellites
are
orbiting
in
three
planes.
Unlike
the
GPS
system,
GLONASS
claims
to
plan
to
use
the
same
levels
of
signals
for
civilian
(CSA)
and
gov-
ernment
use
(SA),

and
civilian
use
is
guaranteed
for
about
the
next
decade.
By
the
late
1990s,
the
project
had
been
divided
into
two
stages:
(I) GNSS-I,
the
first
generation
Russian
GLONASS
and
U.S.

GPS
system
and
(2)
GNSS-2,
the
second
generation
sys-
tem
including
civil
access
with
improved
position-
ing
and
services.
The
MIT
Lincoln
Laboratory
conducts
research
on
the
GLONASS
system
and

reports
progress
and
ob-
servations
on
the
project
on
their
Web
site.
/>Global Network Navigator
GNN.
A
Web-based
in-
formation
service
providing
lists
of
and
information
about
new
services,
sites,
and
related

resources
on
the
Internet.
Global Observing System
GOS.
A
system
for
ob-
taining
standardized
observations of
the
Earth's
at-
mosphere
and
ocean
surfaces
from
ground,
sea,
air,
and
space-based
observation
platforms.
GOS
is

one
of three integrated
core
components of
the
World
408
Weather
Watch
(WWW)
system
and
is
administrated
by
the
World
Meteorological
Organization.
GOS
data
are
valuable
in
weather forecasting
and
meteorologi-
cally
related
agriculture,

climatology,
and
aeronau-
tics.
Space
data
are
available
through
the
Environ-
mental Observations Satellite
(EOS)
system
com-
prised
of
five
near-polar
and
five
geostationary
en-
vironmental observation satellites
with
a variety of
imaging
and
sounding
sensors.

See
Global
Telecom-
munication
System,
Global
Data
Processing
System.
/>Global One
An international
commercial
joint
ven-
ture
of
Sprint, Deutsche Telekom,
and
France
Telecom.
Global Online Directory
GOLD.
A commercial
product
from
VocalTec
that
works
in
conjunction

with
their
Internet
Phone
software.
Internet
Phone
lets
you
plug
a microphone
into
your
personal
computer
and
use
it
as
a
phone
transmitter
to
communicate
with
an-
other person
with
Internet
Phone

capabilities.
The
computer speaker provides
the
equivalent of the
phone
receiver.
Long-distance
calls
can
be
placed
as
though
they
were
local
calls
through
your
ISP,
with-
out
long-distance
charges.
Internet
Phone
connections
are
full

duplex,
connect-
ing
through
the
TCP/IP
transport
protocol.
In
addi-
tion
to
the
features
ofa conventional
phone
call,
chat
lines
and
other
digital
enhancements
are
available.
GOLD
is
the
global
directory

that
stores
information
about
Internet
Phone
users
who
can
be
contacted,
just
as
the
names
of
phone
subscribers
can
be
accessed
through
a
phone
directory.
Global Ozone Monitoring Experiment
GOME.
A
satellite-borne
ozone

European
Space
Agency
(ESA)
research project
launched
in
April
1995
on
board
the
European
Remote
Sensing
Satellite
(ERS-2).
GOME
is
a nadir-viewing passive spectrometer
that
senses
atmospheric
trace
constituents
by
measuring
solar
ra-
diation

scattered
by
Earth's
atmosphere.
Cloud
char-
acteristics, aerosols,
and
surface reflection
can
also
be
measured.
GOME
is
designed
to
sense
in
the
vis-
ible
and
ultraviolet spectra
from
240
to
790
nanom-
eters.

See
GOME
Data
Processor.
/>ME/
Global Positioning System
GPS.
A space- and
ground-based
24-hour
navigational
system
originally
designed
and
used
by
the
U.S.
military
(see
Navy
Navigation Satellite
System),
funded
and
maintained
by
the
U.S.

Department
of
Defense
(DoD).
It
provides
the
means
to
monitor,
update,
and
maintain
orbiting
satellite systems
and
to
determine a
location
on
or
around
the
Earth
through
information
from
these
sys-
tems.

GPS
uses
the
known
positions ofsatellites
as
refer-
ence
points
for
discerning
unknown
positions
on
or
above
the
Earth.
There
are
now
over
20
satellites
in
the
system (some
are
spares), more-or-Iess evenly
spaced,

orbiting
in
12-hour
cycles
at
an
altitude of
about
10,898
miles
(about
400
miles
higher
than
the
original
NNSS).
A system of sophisticated ground
stations
with
antennas,
coordinated
by
a
master
con-
trol
station, administers, deploys,
and

maintains
the
© 2003 by CRC Press LLC
satellites
and
updates
them
when
needed
to
correct
for
clock-bias
errors.
A
variety
of
types
of information
can
be
computed
from
information
from
several
satellites,
including
a
location

or
position
ofa stationary
or
moving
object,
and
coordination
of
time.
This
information
can
be
in-
corporated
into
software applications
in
vehicle-
mounted
or
handheld positioning receivers.
From
military
operations,
to
recreational navigation
on
the

ocean
in
a
kayak,
to
airline
navigation,
GPS
provides
a
wealth
of
data
with
which
to
determine
latitude
and
longitude,
altitude,
and
velocity.
This
information
can
further
be
combined
with

maps
to
record
or
suggest
routes.
GPS
satellites
transmit
timed
binary
pulses
in
addi-
tion
to
information
constants
about
the
current
loca-
tion
of
the
satellite.
The
synchronized
atomic
clocks

aboard
the
satellites permit
the
transmission
of
pre-
cise
timing
tags.
The
combination
of
the
speed of
transmitted electromagnetic
waves
and
the
atomic
clocks
installed
in
GPS
satellites
provides
remarkably
accurate
timing
pulses.

NAVSTAR
Global Positioning System
NAVSTAR
Global Positioning
System
(GPS)
satel-
litefrom
the
24-unit constellation ofplanes and satel-
lites thatprovides militaryandcivilian navigation and
positioning
data.
The
nine-ton satellites orbit
the
Earth
every
12
hours,
emitting continuous positional sig-
nals.
The
signals
can
be
used
to
calculate
time,

loca-
tion,
and
velocity,
depending
upon
the
capabilities
of
the
GPS
receiver.
The
system
is
controlled and
oper-
ated
by
the
50th
Space
Jfing
out
of
Schriever
AFB,
Colorado.
{U.S.
Air

Force
Space Command image.]
The
GPS
Master
Control
Station
(MCS)
is
operated
by
the
50th
Space
Wing's 2nd Space Operations
Squadron
in
Colorado.
This
squad
is
responsible
for
monitoring, controlling,
and
operating
the
GPS
sat-
ellite

constellation.
The
u.S. Air
Force
Space
Com-
mand
Space
and
Missile
Systems
Center
in
Los
An-
geles,
California,
is
the
executive
agent
for
the
De-
partment
of
Defense
(000)
acquiring
GPS

satellites
and
equipment.
There
are
thousands
of
GPS
users
worldwide.
Per-
sonal
GPS
devices
can
be
purchased
for
as
little
as
$180
to
$450,
and
more
sophisticated
ones
are
used

in
all
industries
that
rely
on
location
information:
air-
lines,
shipping
fmns,
ferries,
military
divisions,
etc.
F
or
greater details
on
individual
aspects
of
GPS,
see
differential
GPS,
EAGLE,
Intelligent
Vehicle

High-
way
Systems,
GPS
Operational Constellation,
GPS
Navigation Message, local differential GPS,
NAVSTAR,
Precise Positioning
Service,
Standard
Positioning
Service,
wide
area differential
GPS.
Global
Resource
Information
Database
GRID.
A
global
network
of
environmental
data
centers
coop-
erating

to
generate
and
disseminate
key
environmen-
tal
geo-referenced
and
statistical
data
sets
and
infor-
mation
products.
GRID
centers
are
equipped
to
pre-
pare,
analyze,
and
disseminate environmental
data
that
may
be

used
as
the
basis
for
environmental
as-
sessments.
GRID
is
associated
with
the
Earthwatch
program
and
the
Environment
Assessment
Division
of
the United Nations Environment Programme
(UNEP).
It
was
established
in
1985,
evolving
gradu-

ally
out
of
the
1972
United
Nations
Conference
on
the
Human
Environment
held
in
Sweden.
Following
the
conference,
UNEP
was
created
to
provide
a
fo-
cus
for
a
Global
Environment Monitoring

System
(GEMS)
that
led
to
GRID.
There are a number
of
GRID
centers around
the
world,
including
in
the
U.S.,
South
America,
Europe,
Russia,
Nairobi
(UNEP
headquarters),
Asia,
and
New
Zealand.
For
example,
the

United
Nations
Environ-
ment
Programme
(UNEP)
and
1987
World
Commis-
sion
on
Environment
and
Development project
in
cooperation
with
the
Government
of
Norway
estab-
lished
a
GRID
environmental
information center
in
Arendal,

Norway.
GRID-Arendal
was
opened
as
a
nonprofit
foundation
in
August
1989;
it
communicates
and
cooperates
with
other
GRID
centers.
Global
Software
Defmed
Network
GSDN.
A
high-
volume
commercial
virtual
private

network
service
from
AT&T
that utilizes
AT&T's
Worldwide
Intelli-
gent
Network
(WIN)
to
interconnect
networks
in
the
U.S.
and
other
countries.
GSDN
selects
an
economi-
cal
route
for
external
calls
and

provides
internal
ser-
vices,
including
order
entry,
tracking,
file
transfers,
and
teleconferencing services.
GSDN
is
aimed
at
business
networks.
Global
Standards
Collaboration
GSC.
A
frame-
work
for
the
exchange
of
information

regarding
glo-
bal
standards
development
for
interconnectivity
and
interoperability
of
systems
and
devices.
Thus,
the
GSC
has
been
bringing
together
senior
officials
from
regional,
national,
and
international
standards
bod-
ies

since
1988.
Participating
bodies
include
the
In-
ternational
Telecommunication
Union
(ITU),
the
In-
ternational
Organization
for
Standardization
(ISO),
the
European
Telecommunications
Standards
Insti-
tute
(ETSI),
and
others.
Focal
areas
are

discussed
at
large
conferences.
For
example,
global
radio
stan-
dardization
was
the
key
topic
for
the
2000
meeting
in
Sapporo,
Japan.
Other
topics
ofcurrent
interest
in-
clude
number
portability
for

mobile
communications,
universal
personal
telecommunications
(UPT),
and
intelligent
networks.
Lorg/
409
© 2003 by CRC Press LLC
Fiber
Optics
Illustrated
Dictionary
Global
System
for
Mobile,
Groupe Speciale
Mo-
bile
GSM.
A
digital
cellular
technology
developed
jointly

by
the
telecommunications
administrations
of
Europe.
The
Groupe
Speciale
Mobile
was
founded
in
the
early
1980s,
and
the
Global
System
for
Mo-
bile
(GSM)
was
first
publicly
announced
in
1991

and
has
since
been
standardized
in
Europe
and
Japan.
GSM
was
the
first
fully
digital
system
to
provide
mobile
voice
connections,
data
transfer
services,
pag-
ing,
and
facsimile
at
full

duplex
or
half
duplex
rates
up
to
9600
bps.
GSM
operates
in
two
frequency
ranges:
890
to
915
MHz
for
signaling
infonnation
and
935
to
960
MHz
for
information
transmissions.

GSM
is
a
set
of
standards
specifying
a
digital
mobile
communications
services
infrastructure.
It
is
based
on
a
900
MHz
radio
transmission
technology
and
specifies
related
switching
and
signaling
formats.

An
1800
MHz
Digital
Cordless
System
(DCS)
has
also
been
added.
Since
mobile
systems
typically
support
roaming,
and
since
the
multicultural
makeup
of
Eu-
rope
provides
a
unique
challenge
in

providing
com-
patible
services,
interoperability
has
been
emphasized
in
the
GSM
specifications.
GSM
can
be
described
in
three
categories:
commu-
nications
media,
transceiving
systems,
and
informa-
tion
systems,
as
shown

in
the
GSM
General
Catego-
ries
chart.
The
GSM
subscriber identity
module
(SIM),
also
known
as
a
smartcard,
is
a
security
feature
which
handles
encryption
and
authentication.
It
includes
memory
storage

which
can
be
used
for
dialing
codes
or
other
information
related
to
the
service.
The
SIM
is
also
a
means
to
download
and
display
call-related
information.
See
Future
Public
Land

Mobile
Tele-
communication
System,
Personal
Communications
Network.
Global
Telecommunication
System
GTS.
A
system
of
terrestrial
and
space-based
data
circuits
for
inter-
connecting
meteorological
telecommunications
cen-
ters.
GTS
is
one
of

three
integrated
core
components
of
the
World
Weather
Watch
(WWW)
system
and
is
administrated
by
the
World
Meteorological
Organi-
zation.
GTS
data
are
valuable
in
weather
forecasting
and
meteorologically
related

agriculture,
climatology,
and
aeronautics.
The
GTS
provides
rapid
and
reliable
dissemination
of
observational
meteorological
data.
The
GTS
is
organized
into
a
Main
Telecommunica-
tion
Network
(MTN),
Regional
Meteorological
Tele-
communication Networks

(RMTNs),
and
the
Na-
tional
Meteorological
Telecommunication
Networks
(NMTNs). The World Meteorological Centres
(WMOs)
are
located
in
Russia,
Australia,
and
Wash-
ington,
D.C.,
and
there
are
more
than
a
dozen
regional
hubs
in
Asia,

South
America,
Africa,
Europe,
and
other
locations.
See
Global
Observing
System,
Glo-
bal
Data
Processing
System.
/>Global Title Translation
GTT.
A
telephony
and
ad-
ministration
and
routing
function
that
enables
added
feature

functionality
in
commercial
systems
such
as
Local
Number
Portability
(LNP),
calling
card
ser-
vices,
and
mobile
roaming
support.
GTT
determines
destination
addresses
in
Signaling
System
7
(SS7)
and
other
relevant

network
systems.
When
a
call
is
initiated,
GTT
detennines
the
destination
and
may
include
additional
information,
depending
on
the
fea-
ture
service.
GTT
may
support
multiple
global
title
addresses.
Global Transaction Network

GTN.
AT&T's
exten-
sive 800 service phone network, which was in-
troduced
in
1993.
This
service
supports
enhanced
fea-
tures,
providing
more
flexible
routing
and
number-
ing
services
which
can
be
used,
for
example,
by
air-
line

reservation
systems.
Globalstar A
system
of
48
small
bentpipe
commu-
nications
satellites
orbiting
at
1400
kilometers
(LEO),
for
providing
voice
and
data
services
(data
files,
pag-
ing,
facsimile).
Globalstar
was
established

in
1991
as
ajoint
venture
of
Lora
I
Space
&
Communications,
Ltd.,
QUALCOMM,
Inc.,
and
a
number
of
corporate
partners.
Launching
began
in
February
1998.
In
1999,
G
lobalstar
launched

four
more
systems,
bringing
the
Global System for Mobile (GSM) General Categories
Category
Notes
Media
GSM
works
over
frequency-modulated
(FM)
signals
using
a
combination
of
time
division
multiple
access
(TDMA)
and
frequency
division
multiple
access
(FDMA).

Peak
output
power
varies
with
the
type
of
transmitter
(mobile
station
class),
ranging
from
0.8
to
20
watts.
Frequency
hopping
is
used
to
reduce
interference
and
multipath
fading,
and
encryption

increases
security.
The
data
rate
is
270
Kbps.
Transceiving
There
is
a
base
transceiver
station
(BTS)
associated
with
each
cell
operating
on
fixed
frequencies
unique
to
its
region.
Honeycomb-like
clusters

are
handled
by
base
station
controllers
(BSC),
which,
in
tum,
are
controlled
(routed,
switched,
handed
over)
by
Mobile
Service
Switching
Centers
(MSC).
Information
There
are
databases
associated
with
GSM
that

aid
in
the
administration
of
subscriber
information
and
those
that
aid
in
the
administration
of
security
and
associated
authentication
mechanisms.
There
is
also
an
equipment
identity
register
(EIR),
which
keeps

track
of
equipment
types
and
configuration,
and
can
block
calls
on
stolen
units.
410
© 2003 by CRC Press LLC
total
satellites
to
12.
By
2000,
the
system
was
opera-
tional
and
the
number
of satellites

increased
to
48
over
the
next
two
years.
Globalstar
services
can
be
accessed
with
vehicle-
mounted
or
handheld devices resembling cellular
phones,
and
the
system
is
integrated
with
cell
phone
services
through
dual-modem

handsets.
Remote
us-
ers
can
access
the
system
through
Globalstar
service
providers,
with
fIXed-position
and
wire
line
phones.
Globalstar
is
intended
to
enhance
rather
than
replace
existing
cellular
and
other

phone
services.
Services
are
aimed
at
international
business
travelers,
commer-
cial
vehicle
operators,
marine
craft,
field
scientists,
and
others.
The
competitive
aim
is
low
cost
for
ser-
vice
and
accessories.

GLONASS
Global
Navigation
Satellite
System.
A
Russian
Federation
Global
Positioning
System
simi-
lar
to
the
U.S.
NAVSTAR
system.
GLONASS
is
managed
by
the
Russian
Space
Forces.
GLONASS
provides
all-weather
positioning

coordinates,
veloc-
ity
references,
and
time
information
from
virtually
any
point
on
or
near
the
globe.
More
specifically,
the
GLONASS
system
aids
in
managing
air
and
marine
traffic,
in
supporting

emer-
gency
and
safety
systems,
geodesy,
cartography,
and
ecological
monitoring.
Like
the
American
GPS
sys-
tem,
GLONASS
is
two-tiered.
It
provides
standard
precision
navigation
signals
(SPs)
with
horizontal
accuracy
to

about
63±6
meters
and
high-precision
navigation
signals
(HPs)
with
authorization
and
spe-
cialized
equipment.
The
GLONASS
system
has
launched
more
than
four
dozen
satellites
since
the
first
was
put
into

operation
in
October
1982.
Early
satellites
had
a
lifespan
of
about
two
years,
while
later
satellites
lasted
about
four
or
five
years.
In
general,
the
launches
have
been
suc-
cessful,

although
in
1987
and
1988
there
were
a
num-
ber
of
failures.
Since
1989,
the
orbiting platforms
have
included
geodetic
reference
satellites.
In F
eb-
ruary
1999,
the
Russian
Federation
made
an

open
declaration
of
increasing
international
cooperation
with
regard
to
national
satellite
navigation
technolo-
gies
and
international
navigation
systems.
The
con-
stellation
status
is
reported,
within
a
few
days,
on
the

GLONASS
Web
site.
/>Glossary
of
Telecommunications Terms, FCC A
short
glossary
of
telecommunications
terms
related
mainly
to
delivery
of
broadcast
services
to
consumers
provided
by
the
Federal
Communications
Commission.
Glossary
of
Telecommunications Terms, Federal
Standard

Originally introduced
in
1976
as
MIL-
STD-188-120,
this
archive
has
evolved
through
sev-
eral
revisions
to
become
the
Telecom
Glossary
2000.
It
is
provided
through
the
u.s.
National
Communi-
cations
System

in
print,
CD-ROM,
and
Web
formats,
with
increasing
emphasis
on
electronic
development
and
dissemination.
The
Glossary
is
mandated
for
use
by
all
federal
departments
and
agencies
for
the
prepa-
ration

of
telecommunications
documentation
and
is
available
from
the
National
Technical
Information
Service.
Definitions
from
the
previous
standard
were
revised
and
updated
by
the
FTSC
Subcommittee
to
Revise
FED-STD-J037B.
The
subsequent version,

FED-
STD-l
03
7C
(1996),
was
further
updated
to
Telecom
Glossary
2000,
with
many
of
the
new
definitions
drawn
from
TI
Standards
and
Reports.
The
Glossary
includes
standard
definitions
for

tele-
communications
terms
related
to
antennas,
comput-
ers,
transmissions
media
(e.g.,
fiber
optics),
networks,
audio/video
technologies,
radio
communications,
etc.
Sources
include
government
publications
and
those
of
prominent
telecommunications
organizations
in-

cluding
the
lTV,
ISO,
and
the
American
National
Standards
Institute.
The
Glossary
has
been
reviewed
by
the
National
Communications
System
Member
Organizations,
the
Federal
Telecommunication
Standards
Committee
members,
members
of

relevant
industries
and
federal
agencies,
and
by
the
general
public.
Telecom
Glos-
sary
2000
was
discussed through
members
of
the
TIAI
Ad
Hoc
Glossary
Group.
GMDSS
See
Global
Maritime
Distress
and

Safety
System.
GMDSS
Radio
Maintainer
License A license
granted
by
the
Federal
Communications
Commission
(FCC)
to
maintain
radio
communications
aboard
ships
that
are
equipped
to
comply
with
Global
Maritime
Distress
and
Safety

System
(GMDSS)
regulations.
It
further
confers
the
operating
authority
of
the
General
Radiotelephone Operator License
and
the
Marine
Radio
Operator
Permit.
A
licensed
maintainer
is
re-
quired
by
ships
that
conduct
at-sea

maintenance.
The
license
requires
FCC
Element
1,
Element
3,
and
El-
ement
9
exams
to
be
passed.
GMDSS Radio OperatorLicenseA
license
granted
by
the
Federal
Communications
Commission
(FCC)
to
individuals
deemed
capable

of
handling
radiocom-
munications
aboard
ships
that
are
equipped
to
com-
ply
with
Global
Maritime
Distress
and
Safety
Sys-
tem
(GMDSS)
regulations.
The
licensee
may
oper-
ate
basic
equipment
and

make
antenna
adjustments.
The
license
further
confers
the
operating
authority
of
a
Marine
Radio
Operator
Permit.
Applicants
are
re-
quired
to
pass
the
Element
I
and
Element
7
written
exams.

GMPCS
See
global
mobile
personal
communica-
tions
by
satellite.
GMR
See
giant
magnetoresistance.
GMS
See
Geostationary
Meteorological
Satellite.
GMSK
See
Gaussian
minimum
shift
keying.
GNN
See
Global
Network
Navigator.
GNOME An

open
source
user
software
environment
and
applications
framework
available
to
developers
as
part
of
the
GNU
project.
GNOME
is
typically
dis-
tributed
with
BSD
and
GNU/Linux
distributions
and
is
available

for
other
platforms
as
well.
The
goal
of
the
GNOME
project
is
to
provide
a
user-
friendly
graphical
desktop
environment
and
a
devel-
oper-
friendly base of
tools
for
creating
GNOME-
compatible

software
applications
to
augment
or
re-
place
commercial
operating
systems
and
develop-
ment
environments.
As
the
project
has
evolved,
it
is
411
:
'.:'·.·:.··'

·':.11·:.··:···

·.··
i~:
© 2003 by CRC Press LLC