| Authentication |
The process of validating and identifying a caller as being a legitimate Globalstar
user. |
| Availability |
The probability of attaining a specified level of performance and maintaining that
level for a scheduled period of time. |
| Band |
A related set of frequencies which use a contiguous portion of the spectrum, often for
a similar application. |
| Bandwidth |
The range of frequencies, measured in hertz (Hz), that can pass over a given
transmission channel. The bandwidth determines the rate at which information can be
transmitted through the circuit. |
| Beam |
A portion of the satellite footprint at L-band and S-band. The satellite footprint is
divided into 16 beams. |
| Bent-pipe |
A signal relay scheme in which a terrestrial-based signal is sent to a satellite,
which then relays the signal back to earth with minimal processing by the satellite. |
| Broadcast |
A signal transmitted to all user terminals in a service area, or the process. |
| C-band |
A band of frequencies in the 4 to 8 GHz frequency transmission range that are used for
satellite and terrestrial communications. |
| CDMAs (forward) circuit |
A 1.23 MHz wide spread-spectrum signal (with a unique Walsh code) that resides within
an FDM channel. It typically provides connection between the UT and the Gateway via the
satellite. |
| Channel |
A 1.23 MHz wide frequency band that contains multiple CDMA circuits. |
| Coverage Area |
A geographical area, which moves in time with the satellite, which defines the antenna
coverage of a particular satellite. |
| Digital |
Referring to communications techniques and procedures whereby information is encoded
as binary language, as opposed analog representation of information in variable, but
continuous, wave forms. |
| Downlink |
The portion of a satellite circuit extending from the satellite to the user terminal.
The Globalstar system establishes the service downlink in the S-band region of the
frequency spectrum. |
| Dual Mode |
A handset which has the ability to operate on several frequencies and several types of
communications systems. For example, the Globalstar system will have the capability of
operating in either a cellular or satellite mode. |
| Feederlink subband |
A frequency band 16.5 MHz wide that contains up to 13 FDM channels which corresponds
to a single user-link antenna beam, and is a part of the feederlink band which is
transmitted either to or from the satellite by a gateway antenna. |
| Feederlink band |
A band of frequencies approximately 160 MHz wide containing contiguous feederlink
subbands. There are 16 subbands on the uplink band and 16 on the downlink band. They are
communicated as eight contiguous subbands on RHCP and eight on LHCP polarization, to or
from the Gateway. |
| FDMA |
Frequency Division Multiple Access (FDMA)-communicating devices at different locations
sharing a multi-point or broadcast channel by means of a technique that allocates
different frequencies to different users. |
| FDM channel |
A 1.23 MHz wide channel with a specific center frequency. |
| Finger |
An individual digital channel of a rake receiver. Also called "tine." |
| Footprint |
The portion of the earth's surface covered by the signal from a communications
satellite. |
| Gateway Link |
The link between the Gateway and the satellite. |
| Gaussian channel |
A channel whose only interference is white noise (AWGN-additive white gaussian noise).
|
| Geosynchronous Orbit |
The orbit directly above the equator, about 35,800 kilometers (22,300 miles) above the
earth in space. Also known as GEO, geostationary and Clarke orbit. When positioned in this
orbit, a satellite appears to hover over the same spot on the earth because it is moving
at a rate that matches the speed of the earth's rotation on its axis. |
| Global Roaming |
The ability of a Globalstar subscriber to travel worldwide, and subject to certain
limitations, make and receive Globalstar telephone calls -- particularly outside the
service area of the subscriber's telecommunications service provider. |
| Hand Off |
The process of transferring a subscriber call from one satellite to another. |
| Inclination Angle |
The angle at which a satellite orbit is tilted relative to the earth's equator.
Globalstar satellites are at a 52 degree inclination. |
| Ka-Band |
A band of frequencies in the 18 to 31 GHz range that are available for global
satellite use. |
| Ku-Band |
A band of frequencies in the 10.9 to 17 GHz range that are used for fixed satellite
service applications. |
| L-band |
A band of frequencies in the 0.5 to 2 GHz range that are used primarily for voice
communications. |
| Low Earth Orbit |
A satellite that orbits 400 to 1,600 miles (644 to 2,575 kilometers) above the earth's
surface. 48 to 66 LEOs are needed to cover the entire earth. |
| Medium Earth Orbit (MEO) |
An earth orbit in an altitude roughly midway between the earth and geosynchronous
orbit. Satellite orbits between the altitudes of 1,500 and 6,500 kilometers (930 to 4040
miles) may be considered MEOs. |
| Network |
A term used to describe various communication interconnections. There is a
communication network, a SOCC network, a GOCC network, and the public switched telephone
network. There are also others in the system. |
| Orbital Slot |
A slot above the equator that corresponds to a particular longitude position and can
be occupied by five to ten geostationary satellites. |
| PTT |
Postal, Telegraph and Telephone organization (PTT) -- usually a governmental
department that acts as its nation's common carrier. |
| Phasing Orbit |
Temporary orbit used prior to injection of satellite into final orbit. |
| Rake Receiver |
Receiver having a number of individual digital channels (tines) which can combine
these channels to form a stronger received signal. |
| Registration |
The process of locating a UT to determine which Gateway should serve it. |
| Return traffic circuit |
A CDMA circuit to a Gateway from a user carrying user traffic and other in-band
signaling. Each of these is distinguished by a unique time offset of the long code. |
| Roaming |
Occurs when a cellular or mobile satellite service customer travels outside the
service area of his/her local service provider. |
| Satellite |
An active electronic communications device placed into orbit around the earth
consisting of a payload and bus or platform. |
| S-band |
The portion of the electromagnetic spectrum allotted for transmission in the 2 to 4
GHz frequency range. |
| Service Area |
A geographical area on the ground that is the minimum covered by a gateway and it's
associated satellites. It is normally operated by a service provider. |
| Service Link |
The links between the UT and the satellite. |
| Service provider |
An entity which operates and/or owns one or more gateways and provides services to
customers of the Globalstar system. |
| Short-term fade |
A fade whose duration is less than the round-trip delay (including path delay) from
the Gateway to the user. |
| Soft Handoff |
The process of transferring a circuit from one beam or satellite to another without
interruption of the call. |
| Telemetry, Tracking and Control (TT&C) |
These three functions control and monitor a group of satellites. |
| Transponder |
Component of a communications satellite that receives a signal from earth, processes
and amplifies it, and then re-transmits it to another location on earth. |
| Uplink |
The portion of a satellite circuit extending from the user terminal to the satellite.
The Globalstar system establishes the service uplink in the L-Band. |
| User Terminal (UT) |
Used by subscribers to communicate via the Globalstar satellites. User terminals
include hand-held user terminals powered from internal batteries, mobile units powered
from a vehicle battery, or fixed station units powered from fixed prime power sources. |
| Wireline |
Terrestrially-based telephone line. |
