test2 Flashcards
Define Department of Defense Information Network.
Globally interconnected, end-to-end set of information capabilities, associated processes and personnel for collecting, processing, storing, disseminating and managing information on demand to warfighters, policy makers and support personnel.
Define uplink frequency.
Frequency used by a SATCOM terminal to the satellite is the uplink frequency
Define downlink frequency.
Frequency used from the satellite to the SATCOM terminal is the downlink frequency
Define transponder
Acting as a repeater in the sky, the transponder receives transmissions from the ground or user segments, amplifies the received signal, changes its frequency and transmits the signal back to Earth
Define Signal-to-Noise Ratio
Proportion of the usable or desired signal (S) to the noise (N), or undesired signal
Define Eb/N0
- Energy per bit to noise power spectral density ratio
- Signal-to-noise ratio per bit
- Eb is signal energy per bit
- N0 is noise energy per Hertz of noise bandwidth
Define Frequency Division Multiple Access
Technique used for sharing transmission channel among two or more users by assigning each to an exclusive frequency band within the channel
Define Time Division Multiple Access
Technique used for allocating a discrete amount of frequency bandwidth to each user, in order to permit many simultaneous conversations with each user assigned a specific timeslot for transmission
ID the purpose of the Standardized Tactical Entry Point (STEP)/Teleport
Serve as entry points for tactical forces to the Department of Defense Information Systems Network and are strategically located throughout the world
ID the purpose of the Satellite Access Request
Prepared and submitted for access to strategic satellite systems to provide worldwide connectivity in the tactical, warfighting environment
ID the purpose of the Gateway Access Request
Prepared and submitted for access to the DISN in order to provide worldwide secure and non-secure voice, video and data connectivity in the tactical, warfighting environment
Define Antenna Control Unit
Performs satellite acquisition and tracking
Define High Power Amplifier
Boosts the transmit signal (uplink) to enable the antenna to beam the signal up to the satellite
Define Low-Noise Block Downconverter
- Used in receiving (downlink) of satellite signals
- Combination of a low-noise amplifier and frequency mixer
- Receives signal from satellite, amplifies it, downconverts the block of frequencies to a lower block usable by the modem
Define Block-Upconverter
- Used in the transmission (uplink) of satellite signals
- Converts a band of frequencies from a lower frequency to a higher frequency usable by the satellite
Define Modem
Used to convert data into binary form and back
ID the definition of a point-to-point satellite communications network configuration
- Each terminal combines all information to be sent to the distant end into a single output and transmits it to the satellite.
- Unique transmit frequency assigned to each terminal with enough difference in the frequency to prevent signals from interfering with each other
- Each signal is processed by the satellite and retransmitted toward the earth to become the receive signal for the distant end terminal
sat circle to sat circle
ID the definition of a hub-spoke satellite communications network
- Hub-spoke configuration performs the same communication function as four full duplex PTP satellite links
- Unlike PTP, two frequency assignments are NOT required for each link, each terminal requires only one frequency assignment
- Outgoing signals from the hub terminal to all distant end terminals are combined and transmitted at the same center frequency, all distant end terminals receive the same signal after the satellite retransmits it
- Each spoke terminal then separates the information intended for that terminal from the combined signal and ignores the information intended for other terminals
- Only signals destined for the hub are combined into the spoke transmissions
ID the definition of a mesh satellite communications network configuration
- Similar to hub-spoke configuration
- Terminals that communicate with only one distant end terminal operate in the same manner as spoke terminals in a hub-spoke configuration
- Each terminal with multiple distant ends transmits combined signals to all distant end terminals exactly as a hub terminal in a hub-spoke configuration
- Unlike operation in a hub-spoke configuration, the signals received by terminals with multiple distant ends include information intended for other terminals, in that case, the desired information must be separated from those signals and the remaining ignored in the same manner as signals received by spoke terminals
