Block 1 Flashcards
Satellite communications (SATCOM) systems inherently facilitate…?
beyond line of sight connectivity
A robust SATCOM architecture provides either ___ coverage or ___-___ coverage.
equatorial coverage (nonpolar)
high-latitude coverage (includes poles)
SATCOM provides national and strategic leadership with a means to…?
maintain situational awareness and convey their intent to the operational commands responsible for conducting joint operations
What are the three segments of SATCOM?
Space
Link
Ground
The Space segment has __ parts and what are they?
Two parts:
- Platform
- Payload
What is the “platform” part of the space segment?
consists of the basic frame of the satellite
“What is the “payload” part of the space segment?
provides space-based capabilities to the users and distinguishes one type of satellite from another
The payload’s functions and capabilities are the main reason satellites are placed into orbit (for example the fact they provide communication)
The Space segment is responsible for providing what?
Provides passive and directive gain through the use of transmit and receive antennas and onboard amplifiers.
What is the “Link” segment?
Uplink and downlink to/from the terminals
What is the “ground” segment?
Comprised of equipment that receives and transmits signals to the satellite from the Earth.
These can vary from hand held devices to fix or mobile terminals.
What is the “control” portion of the ground segment?
Responsible for the operation of the overall system including platform, payload and network control.
This consists of worldwide satellite control facilities, systems onboard the satellite and communications networks linking the control facilities.
Satellite control is the means by which WGS and DSCS assets are used to maintain and restore maximum satellite performance under changing traffic conditions, natural or man-made stresses, disturbances, and equipment disruption.
The Ground segment contains the RF equipment that transmits and receives.
What is the transmit path?
- Upconverts the IF (intermediate frequency) sub-carrier to the assigned frequency in the correct band range
- The outputs of the up-converters are then combined and amplified using HPA’s prior to reaching the antenna
The Ground segment contains the RF equipment that transmits and receives.
What is the receive path?
- The distant end’s antenna provides reflector passive gain and then LNA provides directive gain by amplifying the signal
- The signal is split into multiple outputs for the down-converters to amplify the signals and convert them into IF (70 MHz) or L-Band (1-2 GHz)
What is DCSS?
Digital Communication Subsystem within the Ground Segment that takes place at the TCF (Tech Control Facility)
What kinds of things occur at the DCSS?
- Multiplexes/demultiplexes VF inputs and outputs
- Encrypts/decrypts VF inputs and outputs
- Multiplexes/demultiplexes digital inputs and outputs
- Modulates IF sub-carriers of 70 MHz and 1-2 GHz
What are some users of WGS and DSCS?
- Commander in Chief (POTUS)
- Unified Combatant Commands (UCCs)
- National Airborne Operations Center (NAOC)
- White House Communications Agency (WHCA)
- North Atlantic Treaty Organization (NATO)
- Air Force Satellite Communications (AFSATCOM)
- Allied special users
WGS and DSCS provides range extensions for which users?
- World Wide Military C2 System (WWMCCS)
- Department of Defense Information Network (DODIN)
- Jam Resistant Secure Communications (JRSC) Networks
- Tactical Warning/Attack Assessment Networks
- Global Broadcast System (GBS)
- Navy Flagship Command and Control Networks
- Ground Mobile Forces (GMF) and (C4I) AFLOAT
communications
What is the electromagnetic spectrum?
The electromagnetic spectrum can best be described as the entire span of frequencies or wavelengths that can possibly be exhibited
by electromagnetic waves.
What part of the frequency spectrum does satellite communications operate in?
UHF, SHF and EHF
But primarily, SHF
What are the limitations to using EHF?
Technologically immature
Very susceptible to weather
What is the frequency range for SHF?
3-30 GHz
What is the frequency range for EHF?
30-300 GHz
It is a characteristic of electromagnetic transmissions that noise power in a channel increases as the channel ___ increases.
bandwidth
A satellite transponder is built to receive and transmit signals within…?
A specific band and channel of the spectrum
The number of hertz (Hz) spanned by this limited band of frequencies describes the transponder’s…?
RF BW
____ ____ equals its potential capacity to pass communications and data at higher throughput rates.
Transponder Bandwidth
Greater BW increases ___ ___ only if the conditions in all parts of the transmission signal path can be adjusted to minimize noise and to maximize the signal power to noise ratio without distorting the signal.
throughput capacity
The WDC payload capabilities is applicable to which satellites?
Block II Follow-On (B2FO) F7
Block II Follow-On (B2FO) F8
WGS provides ___ transmit/receive beam pairs?
19
This means it supports 19 coverage areas
How many NCAs does WGS have?
8 Ka-band NCAs
How many ACAs does WGS have?
2 Ka-band ACAs
How many EC areas does WGS have?
1 X-Band EC area
How many shapeable beams does WGS have?
8 X-Band shapeable beams
Coverage areas for WGS are or are not impacted by the WDC upgrade?
Not impacted
WGS provides ___ antennas to support the 19 coverage areas.
14
For F4+, what were changed about the antennas of WGS?
The two 10-inch ACAs antennas were modified to be the same as NCAs. This made the east side of the pallet identical to the west side.
In addition, the ACAs were moved to the outside of the pallet.
In F1-F3 satellites, the ACA’s were smaller than the NCAs.
What does NCA stand for?
Narrow Coverage Area
What does ACA stand for?
Area Coverage Area
What does RHCP stand for?
Right Hand Circular Polarization
What does LHCP stand for?
Left Hand Circular Polarization
What do lettered frequency bands indicate?
That they can be switched between prime and non-prime locations but cannot be assigned to both simultaneously.
Lettered channel designators
indicate that the channel can be selected, exclusively, from one of two beams.
What frequency band is WGS F1-F7?
X-Band and Ka-Band
How many redundant X-Band channelizer ports were activated for BOL (Beginning of Life) use on F7?
6 (3 UL and 3 DL)
** This is known as “redundant ports activation” or “RPA”
How many redundant Ka-Band Channelizer ports were activated for BOL (Beginningof Life) use on F7?
8 (4 UL and 4 DL)
What is the difference between footprints for WGS F1-F7 in X-Band and Ka-Band?
X-Band Antennas are steerable and shapeable beams and Earth coverage. They transmit LHCP and receive RHCP.
Ka-Band Antennas are gimbaled dish antennas offering Narrow coverage and Area coverage. They are diplexed polarized on both transmit and receive.
What is unique to satellites F4-F7 on WGS in the Ka-Band RF Bypass channels?
This allows users to occupy more than the legacy 125 MHz bandwidth. Now, there is one 400 MHz channel in each RF bypass beam
Ka-band RF bypass channels are processed through the..?
RF Bypass Channel Amplifiers (CAMPs)
When a bypass path is utilized, the corresponding CAMP is turned on, otherwise, when the bypass path is not utilized, the CAMP Is off.
When the WGS WDC frequency plan was implemented it allowed processing bandwidth to…?
quadruple from 125 MHz to 500 MHz
*** These 500 MHz channels are referred to as “super-channels” which differentiates it from the legacy channels used on F1-F7 WGS payloads
The WGS WDC Frequency plan applies to what?
F8+ (X-Band and Ka-Band)
Which beams on the WGS have switchable polarization?
NCA7, NCA8, ACA2
The switchable polarization is controlled by…?
Bandwidth selection switches
In the WGS Block II both the X-Band and the Ka-Band subsystems utilize frequency reuse via…?
spatial frequency reuse/spatial isolation
How is the digital channelizer able to crossband?
All X-band and Ka-band uplink channels are converted to a common baseband frequency through
two down conversions: RF to IF and IF to baseband. The down-converted signals then enter the analog front end of
the channelizer where they are converted from analog to digital signals. In addition, for the X-band signals, the
channelizer performs the input spectrum frequency inversion. The channelizer is a digital filter and switch, which
breaks each channel into 48 subchannels. Subchannels can be routed (individually or as groups) from any input to
any output(s) of the channelizer. Thus crossband connectivity is realized between X-band and Ka-band
The digital channelizer also allows gain of ___ or ___ of subchannels to be adjusted
individual or groups
The digital channelizer allows combination and/or replication of subchannels through the use of what…?
Fan ins
Fan outs
Spectral Monitoring
Each beam can contain up to ___ channels.
4
Each channel is 125 MHz and is broken down into 48 subchannels that are ___ MHz.
2.6 (rounded up)
125/48 = 2.60416
The 47 MHz channels (x-band rx/tx channel 1/4) each have ___ subchannels.
18
The 50 MHz channels (x-band earth coverage beam) each have ___ subchannels.
19
The ___ ___capability allows users who require more than 125 MHz of bandwidth to bypass the WGS beam to channel channelization processing (BDCA, channelizer and BUCA.)
RF Bypass
*** It provides this through two independent bypass paths.
What is channelization?
The process of separating a range of frequency into smaller groups of frequency
With channelization, each WDC port can process an entire 500 MHz beam (super-channel) whereas with the older model (F1-F7) up to 500 MHz of spectrum can be processed from a…?
coverage area beam
Essentially, a beam can only process one 500 MHz of spectrum where with WDC a designated channel can process 500 MHz
WDC still performs ___ ___ ___ but can now group subchannels across channel boundaries.
legacy channel processing
There are 4 channels and then 48 subchannels within F1-F7 satellites. How many subchannels are there in a super-channel?
192 subchannels (aka super-channel)
This is because superchannels combine 4 channels into one super channel. Those 48 subchannels x 4 channels = 192 subchannels.
It’s important to remember that this is not creating a larger bandwidth to operate in overall the entire span of frequency given but creates a larger bandwidth within the channels themselves.
What is the total bandwidth of the F8?
8426 MHz over 73 total channels
- 1 x-band EC beam = 1 EC channel = 50 MHz BW (50 x 1)
- 8 x-band phased array beams = 32 channels = 3376 MHz BW (32 x 125)
- 10 ka-band GDA beams = 40 channels = 5000 MHz BW (40 x 125)
WGS Channelizer allows signals from any uplink beam to be routed to any downlink beam via…?
Frequency Cross Banding
The same frequency can be used in each coverage area.
Spatial frequency reuse
*** For example, same 125MHz channel can be downlinked into 2 different coverage areas.
What does CNPS stand for?
Common Network Planning Software
If the beams overlap during spatial frequency reuse, degradation will occur from…?
co-channel interference
Co-channel interference or CCI is crosstalk from two different radio transmitters using the same channel
Switchable polarization is possible through what?
Polarization Frequency Reuse
This is only possible on Ka-band antenna; up to 3 may be switched.
Polarization for antennas may be switched which allows Ka-band coverage areas to be…?
placed closer together
The biggest limiting factor to Polarization Frequency Reuse is…?
Rain
This can cause depolarization of the oppositely polarized spectra
Beam Select Switching is not applicable to F8 beams because?
They are already 500 MHz
Spatial Frequency Reuse can only combine
Beam Selecting Switching is possible through the __ __ __ which results in Spatial Frequency Reuse
Bandwidth Switch Matrix
- For the selectable channel paths, this chooses which beam to route the signal to in the beam combining network.
- Beam Selecting Switching is not applicable to F8+ beams which are all 500MHz (only applies to F1-F7)
Subchannels can be routed from any uplink antenna to multiple downlink antennas.
Fan-Out
Multiple uplink subchannels (or subchannel groups) from separate uplink coverage areas can be “___ ___” to a single downlink subchannel (or subchannel group) within a single downlink coverage area.
Fanned-in
What are some of the differences that came with the Digital Signal Processing (DSP) capabilities of the Widband Digital Channelizer (F8+)?
- Divides 500 MHz super-channels into 192 subchannels (2.6 MHz) - Legacy divides 125 MHz channels into 48 subchannels
- Provides TX Subchannel Automatic Level Control (SALC) - Legacy provides TX channel (not subchanne) ALC
- Provides RX and TX suchannel limiters - legacy does not provide subchannel limiters
- Provides RX and TX subchannel power meters - legacy provides only RX subchannel power meters
- Provides RX and TX subchannel phase offset adjustment - legacy does not does provide this
Difference between F1-F7 Channelizer Switch and F8+ Channelizer Switch:
- F1-F7 - 2 stages
F8+ - 3 stages (ingress, middle, egress) - F1-F7 - subject to back-plane routing constraints resulting in some blocked routing scenarios. F8+ - utilizes Re-Arrangeable Non-Blocking (RANB) design that allows existing traffic to be rerouted to allow new traffic to be routed without disruption
- F1-F7 - 48 x 125 = 6,000 MHz capacity
F8+ - 28 x 500 = 14,000 MHz capacity
Automatic Level Control (ALC) has three modes:
Linear (bypass) Mode
Constant Power Mode
Limiter Mode
ALC is implemented at the __ side of the channelzer
TX
Nominally ALC will be enabled in which modes for F1-F7 and F8+?
F1-F7 = Limiter Mode (across the entire channel)
F8+ = Constant Power Mode (across selected subchannels group)
F8+ utilizes a new SALC that allows power to be level controlled…?
Across subchannels or group instead of entire channels.
Channelizer switch resource planning for F8+ is made via?
GSCCE whereas legacy satellites are through CNPS
Spectrum Monitoring System (SMS) is used interchangeably with what?
Spectrum Information Gather (SIG)
Channelizer only supports simultaneous operation of ___ SMS processes/scripts
two
What is SMS?
Permits monitoring segments of the uplink spectrum via a common downlink segment
This utilizes channelizer multicast capability to simultaneously route selected uplink segments to a monitoring downlink as well as the intended comm downlink
This utilizes channelizer digital switching/signal routing capability to select alternate in-band command channels when the current command channel is lost.
Command Channel Search
CCS
The ___ ___ ___ is what supports the CCS algorithm
Spacecraft Control Process (SCP)
This is an algorithm in the Spacecraft Control Processor (SCP) that provides the ability for the SCP to respond to certain payload faults.
Payload Fault Protection (PFP)
The PFP has 42 “test” in use
The __ ___ __ antenna design allows the total output power of the array to be distributed as specified by the planner.
TX phased array
This means the total array output power can be placed in a single beam or eventy distributed between beams.
The TX array power distribution is controlled by __ __ __ attenuator settings.
Beam Driver Assembly (BDA)
The SMS and CSS is utilized for F7 via CNPS whereas the F8+…?
uses GSCCE
This segment is comprised of equipment that receives and transmits signals to the satellite from earth.
Ground segment
These can vary from hand-held devices to fixed or mobile terminals
It is a characteristic of electromagnetic transmission that __ __ in a channel increases as the channel BW increases.
noise power
Increasing the ___ of a satellite transponder can expand the number of available channels.
amplification (transmit power)
*** however, more power requires more weight, so the number of channels also affects the launch weight limitation of the delivery vehicle. This necessitates the use of other means to increase capacity (i.e. multiple polarization techniques)
Greater BW increases throughput capacity only if the conditions in all parts of the transmission signal path can be adjusted to minimize the __ and to maximize the signal power to noise ratio without distorting the signal.
noise
The use of multiple ___ ___ increases the number of channels per satellite and allows USMILSATCOM users to stay within globally mandated bandwidth allocations
polarization techniques
*** The satellite’s large footprint covers about 1/3 of the earth’s surface
What are the modes of access?
FDMA
TDMA
NCW
SSMA
OFHMA
Which mode of access does a majority of WGS/DSCS traffic use?
FDMA
This mode of access is associated with early cell phones.
SSMA
Spread Spectrum Multiple Access
This mode of access provides anti-jam (AJ) SATCOM support.
OFHMA
Orthogonal Frequency-Hopping Multiple Access
How does FDMA work?
Users access the satellite transponder by transmitting carriers at different frequencies within the same channel.
What are the advantages of FDMA?
- No special circuitry or equipment required
- No network timing (like TDMA) required
- Voice can be transmitted in normal analog form
- Very high data rates
- Relatively inexpensive
What are the disadvantages of FDMA?
- Vulnerable to jamming
- Intermodulation products waste power and add noise to the signal
- Operating frequencies must be carefully selected to reduce intermodulation
- Uplink power coordination is required
- Requires guard bands which waste space
How does TDMA work?
Each earth terminal in a TDMA network is assigned a specific time slot to transmit and all uplinks use the same transmit frequency
What are the advantages of TDMA?
- Very efficient in terms of used BW
- High data rates
- Minimal earth terminal power coordination
- No intermodulation distortion for the carriers in the TDMA
Network
What are the disadvantages of TDMA?
- Very vulnerable to jamming
- Requires network timing, synchronization markers and
preamble coding - Not suited to analog signals
- Requires 3 to 6 dB more transmit power
- Costly
How does SSMA work?
- Each earth terminal is assigned a specific transmit and receive
code. - All users transmit in the same bandwidth simultaneously.
- Users employ signals which occupy a significantly larger
bandwidth than the symbol rate.
What are the advantages of SSMA?
- Very jam resistant
- Enemy cannot tell how much
data is being transmitted - No guard bands required
- All terminals transmit on the
same frequency - Low peak power required
- It can transmit under a FDMA or
TDMA signal.
What are the disadvantages of SSMA?
- Requires careful network planning, timing and synchronization
- Data rates generally lower and are greatly reduced if operating
in an anti-jam mode - Is not well suited to analog signal formats
- Very costly
The signal transmitted from a ground terminal antenna up to a satellite is called an ___, and the transmission from a satellite to a ground terminal antenna is called a ___.
uplink
downlink
The most common type of MILSATCOM antenna is the ___ ___ which focuses the radio waves it collects into the opening of the waveguide.
parabolic dish
What pieces of equipment at the antenna site can restore the signal to a useful level for processing?
Reflectors, low noise amplifiers, and sophisticated receivers
The __ of an antenna is a measure of its ability to concentrate energy being beamed to or from the satellite.
gain
An antenna can be designed and ___ to focus a signal into a desired area.
shaped
If the dish is large, then..?
It will pick up more signals from space and be able to transmit with less power
If the dish is small, then…?
It will pick up fewer signals from the satellite and require more power.
If the low noise amp is powerful, then..?
The dish is small and less expensive
If the low noise amp is not so powerful, then…?
The dish must be bigger and more expensive
If the dish is close to the center of the footprint, then…?
The dish is small and the low noise amp does not need to be so powerful
If the dish is far from the center of the footprint, then…?
The dish must be larger and the low noise amp more powerful
What is JWICS?
Joint Worldwide Intelligence Communications System
Terminals are categorized by type. What are these types?
Anchor Stations: this consists of strategic or enterprise terminals
Mobile Terminals: this includes tactical and transportable, airborne terminals (fast mover) and shipboard terminals (C4I)
What is the terminal signal theory?
Uplink - the ground segment receives IF signals from one or more modulators, converts them to satellite uplink carrier frequencies, amplifies the carriers’ power level, and transmits them to a satellite.
Downlink - the ground segment receives the satellite downlink signals, amplifies the signals, converts the signals to IF, and feeds them to one or more demodulators
What are the components to a terminal/ground segment?
Antenna
LNA/LNB
Transmitters (HPA)
IPAs
Upconverters
Downconverters
Modems
Earth terminals are broken down into three categories. These are…?
- Standardized Tactical Entry Point terminal
- Teleport Terminal
- Monitoring Terminal
This terminal is a specially equipped strategic earth terminal designed to allow tactical terminals access to the Defense Information Systems Network (DISN)
STEP
___ dictates which strategic earth terminals can be used as STEP sites
DISA
The STEP program is not determined by a matter of SATCOM equipment compatibility, but instead by…?
Services that the data level user can provide
This terminal program is an extension of the STEP program.
Teleport
*** These terminals are strategic earth terminals equipped with the capabilities to access military and commercial C, X, Ku, Ka UHF, EHF and AEHF band satellites.
This terminal is any strategic earth terminal with the equipment to support spectrum monitoring functions, either WSOC’s terminal, co-located, or remote.
Monitoring
*** AKA - MET terminal
The WSOC utilizes __, ___ and __ from METs to control and monitor multiple satellies at a time.
HPAs, LNAs and antennas
Explain the difference between strategic,operational and tactical levels.
Strategic - This level involves a strategic concept, plans
for preparing all national instruments of power for war or conflict, practical guidance for
preparing the armed forces, and leadership of the armed forces to achieve strategic
objectives.
Operational - The operational level is concerned with employing military forces in a theater of war or
theater of operations to obtain an advantage over the enemy and thereby attain strategic
goals through the design, organization, and conduct of campaigns and major operations.
Tactical - In the traditional sense, the various operations that make up a campaign are themselves
made up of maneuvers, engagements, and battles. From this perspective, the tactical level
translates potential combat power into success in battles and engagements through
decisions and actions that create advantages when in contact with or in proximity to the
enemy.
Which delta is in charge of SATCOM management, personnel, and facilities for RSSCs, operations and maintenance for WSOCs and provides WGS, DSCS and GBS SSE (SATCOM System Expert)
Delta 8
“The Task Force”
That’s me!
Who is in charge of:
- Being the focal point for engineering, operational, and technical expertise for assigned systems.
- Supports the USSPACECOM integrated management framework to assess, plan, analyze, and integrate SATCOM.
- Manages assigned systems to ensure that standardized, high quality, integrated SATCOM.
SATCOM Office
Who is in charge of:
- Planning and coordinating Wideband transmission requirements.
- Creates Satellite payload reconfigurations and restoral plans.
- Analyzes requirements for day-to-day users.
RSSCs
Who are the Space Ops Squadrons?
53rd SOPS
4 SOPS
What is the difference between what 53rd SOPs and 4SOPS provides?
53rd SOPS -
Wideband Payload Control
Wideband Network Control
4SOPS -
Wideband Bus Control
MILSTAR Payload and bus control
EPS Payload and Bus control
What agencies are all involved in MILSATCOM?
- Joint Chiefs of Staff (JCS)
- Commander United States Space Command (USSPACECOM)
- Combined Force Space Component Command (CFSCC)
- Task Force - SATCOM/Del 8
- SATCOM Office
Who is in charge of:
- Providing operational policy, guidance, and procedures for the planning, management, employment and use of SATCOM resources.
- Resolves conflict regarding satellite allocations and user precedence.
Chair of the Joint Chiefs of Staff (CJCS)