3C Flashcards
___ includes those systems
(space, control, and terminal segments) owned and operated by the Department of Defense.
MILSATCOM
MILSATCOM also includes ___ gateways (to include DoD gateways) and ___ gateways.
enterprise
service
___ encompasses DoD-leased bandwidth, DoD-owned or leased commercial-band terminals and gateways landing DoD missions, and COMSATCOM used by the Department of Defense but provided by commercial entities using commercial terminals.
COMSATCOM
To understand SATCOM you must understand the three distinct segments of satellite
communications and the different subsystems of which they are comprised. Those three segments are:
- Space Segment
- Command and Control Segment
- Terminal Segment
This segment is comprised of the space vehicles that carry satellite communications
payloads.
Space Segment
“___” are groups of satellites.
Constellations
___ are diverse and complex pieces of equipment that perform a specific function
for a specific length of time (service life).
Satellites
All satellites consist of at least five subsystems housed within a framework known as the “___”.
bus
The “___” contains the support vehicle and all the control subsystems that allow the satellite to function.
bus
What are the five subsystems of Satellites?
Those subsystems are the power subsystem, the propulsion subsystem, the telemetry, tracking, and control (TT&C) subsystem, the beacon subsystem, and the communications subsystem.
The bus is the ___ or composite structure of the satellite spacecraft.
metal
The ___ is the framework that holds all of the components together as one integral unit that allows the satellite to function in the vacuum of space. The ___ must be strong enough to withstand launch, yet light enough to not
restrict payload weight.
bus
The ___ ___ generates and regulates the power required by the satellite systems to operate.
power subsystem
The most common type of power subsystem in use today is a combination of
large solar panels and rechargeable batteries
Most satellites use an onboard ___ ___ to correct launch vehicle injection errors and perform periodic position changes for different Earth coverage patterns. ___ ___ also aid in stabilizing a satellite against atmospheric drag, gravity from the Moon, and other external factors.
propulsion subsystem
The ability to collect data remotely.
Telemetry
This subsystem enables controllers on the ground to monitor the spacecraft and its
subsystems. The ___ subsystem can execute commands sent from the Control Segment and
send its own data back to the control segment to ensure optimum performance.
Telemetry, Tracking and Control (TT&C)
This subsystem is a fixed frequency signal transmitted from the satellite that enables the control segment to determine a spacecraft’s position in space. Controllers use this data to calculate the look angle of a terminal’s antenna to the satellite.
Beacon
This subsystem allows the satellite to send radio signals between terminals or between other satellites.
Communications
Communications satellites are equipped with ___.
transponders
A transponder is similar to a
transceiver in that it receives a signal and retransmits it. However, instead of using the same frequency, transponders change the frequency they send back down from the frequency they initially received. These signals are known as ___ frequencies and ___frequencies.
downlink and uplink
The ___ ___ ___ segment consists of the systems on the ground that are responsible for sending commands to and from the satellite.
command and control segment
Satellites are constantly monitored and maintained
through the ___ ___ to keep them functioning properly.
control segment
The control segment is responsible for ___ ___ ___ including spacecraft control, payload control, and communications network control.
overall system operation
The ___ subsystem is heavily involved in managing these different controls and facilitates the sending and receiving of commands and data from ground controllers.
TT&C
What are the three different types of controls that fall under the Command and Control Segment?
Spacecraft Control
Payload Control
Network Control
This control includes the stabilization, maneuvering, repositioning, and the proper
functioning of the systems onboard the entire spacecraft.
Spacecraft
This control involves operation and control of the payload on the spacecraft. The ___ is
the primary reason a spacecraft is in orbit in the first place. Where spacecraft control refers to the body of the spacecraft (the bus), ___ control refers to the inner workings of the spacecraft (beacon and/or communications subsystems).
Payload
This control encompasses satellite control and monitoring stations. Control and monitoring stations are necessary for keeping the spacecraft functioning in orbit and are strategically located
around the world to perform spacecraft and payload control.
Network
This segment encompasses the personnel, equipment, and
facilities that use the capabilities provided by the satellite payload.
Terminal
Can terminals operate practically anywhere?
Yes - such as at fixed bases, on ground vehicles, ships and/or aircraft.
