SATCOM Terminal Characteristics

UNIT 1. SATCOM TERMINAL CHARACTERISTICS

Objective 1a: Satellite Communications (SATCOM) Terminal Characteristics

  • Introduction:

    • SATCOM terminals connect the military to cyberspace in challenging environments.
    • Terminals are complex and pass tactical information over long distances, requiring high precision.
    • Terminals can be located on the ground, in the air, or on a ship.
    • SATCOM terminals vary in configuration but share common characteristics: reflector, feed horn, amplifiers, and modem, interconnected by cables.

  • Reflector:

    • Typically a parabolic dish used for transmitting and receiving microwave frequencies.
    • Parabolic shape provides higher gain, useful for capturing downlink signals.
    • Size of the reflector is inversely proportional to the frequency.
    • During transmit: signal leaves the feed horn, strikes the dish, and focuses into a concentrated beam.
    • During receive: signal reflects off the dish into the feed horn for further processing.

  • Feed Horn:

    • A horn antenna that conveys signals to and from the dish, often attached to waveguides.
    • Delivers signals between the transmitter/receiver and the parabolic dish.
    • During transmit: focuses outgoing radio frequency into a beam reflected off the parabolic dish.
    • During receive: collects incoming signal from the satellite reflected off the parabolic dish and relays it.
    • Capable of adjusting for different types of polarization:
      • Linear polarization: adjustable to horizontal or vertical.
      • Circular polarization: adjustable to right-hand or left-hand polarization.
    • Feed horns are band-specific (e.g., switching from X-band to Ka-band requires switching the feed horn).

  • Satellite Modem:

    • Modem stands for modulate-demodulate.
    • Converts digital data to usable electromagnetic waves during transmit and vice versa during receive.
    • During transmit:
      • Data Terminal Equipment (DTE) sends digital information (baseband) to the modem.
      • Modem modulates the information into an analog Intermediate Frequency (IF).
      • IF is sent to the Up Converter for final translation to the transmit frequency.
    • During receive:
      • The down-converted signal is sent to the modem.
      • Modem demodulates the signal to extract the information for the DTE.
    • Attributes that assist the modem:
      • Forward Error Correction (FEC):
        • Assists with sub-optimal signal-to-noise level.
        • Adds redundancy to the data stream to fix errors caused by noise and interference.
        • Multiple copies of the message are sent, and the receiving end recreates a more error-free message.
        • FEC rates (e.g., 1/2, 2/3, 3/4, 7/8) determine the number of copies sent.
      • Scrambling:
        • Obfuscates analog data streams, making it difficult to read without the proper key.
        • Randomizes data but is not encryption.
        • Encryption uses mathematical algorithms to protect information.
      • Data Interfaces:
        • Medium in which information is transmitted/received to the DTE.
        • Modems can house connections such as RS-232, RS-422, HSSI, EIA-530, and Ethernet.
      • Access Methods:
        • Methods to efficiently use a satellite’s bandwidth capacity.
        • Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), and Demand Assigned Multiple Access (DAMA).
        • Modems are typically designed to use one access method, but modern modems can use multiple.

  • Coaxial Cables:

    • Medium to pass signals throughout the terminal.
    • Typically copper coaxial cables (modern equipment may use fiber).
    • Grounded outer conducting shield (braided shield) makes the inner conductor less vulnerable to electromagnetic interference (EMI).

Objective 1b: Multiband Satellite Terminals

  • Introduction:

    • Satellite terminal manufacturers engineer equipment to work on multiple frequency bands.
    • Allows seamless transition to different frequency bands for redundancy and versatility.

  • Multiband Satellite Terminals:

    • Operate on multiple frequency bands, including military and commercial satellites (C, X, Ku, or Ka-bands).
    • The AN/TSC-179 or Ground Multiband Terminal is utilized.

  • Capabilities:

    • Dual Hub, Quad-Band Terminal able to operate in C, X, Ku, or Ka Bands:
      • GMT is capable of one uplink and six downlinks per hub, thus 2 uplinks and 12 downlinks with dual hub.
      • Second hub requires an additional antenna.
      • Hub 1 and 2 are identical and interchangeable for quick troubleshooting.
    • Capable of communicating with military and commercial constellation and with legacy GMF terminals like the USC-60A, AN/TSC-94A and AN/TSC-100A.
    • The GMT has a large footprint, taking up two 463L pallets, which can make its deployment capabilities specific.
    • There are 29 transit cases: 19 antenna cases, 6 electronics cases, 2 PDP cases and 2 spare equipment cases.
    • 2 pallets are required to ship all 29 cases; antenna and electronics cases fit on one 463L pallet and the spare equipment cases and PDP cases require a second pallet.
    • Requires two qualified personnel to setup and tear down.
    • Compatible with antennas:
      • Small Aperture Antenna (SAA).
      • OE-361 Quick Reaction Satellite Antenna (QRSA).
      • Lightweight High Gain X-band Antenna (LHGXA).
      • Large Aperture Multiband Deployable Antenna (LAMDA).
      • Quad-band Large Aperture Antenna (QLAA).

  • Power Distribution:

    • Adequate power is critical for communications.
    • Residential setting: power accessible through an outlet.
    • Deployed environment: generator in use.
    • Stemming from the generator would be a Power Distribution Panel (PDP) that would be dedicated for a suite of equipment.
    • PDPs are designed for use with 60 amp, five-wire power cable (part No. 60-A-5c-L3-2) or equivalent government inventory.
    • The PDPs are equipped with MS90558C32412P and MS90555C32412S input and output power connectors and 60-amp input and output main circuit breakers.
    • Local PDP must be within 50ft of local power source.
    • Remote PDPs can be separated from the local PDP up to 250 feet (300 feet from source) with acceptable voltage drop by daisy chaining five of the 50-foot segments of 60-amp cable.
    • Uninterruptible Power Supply (UPS) can preserve power in the event of facility or generator failure.
    • UPS sits between the communications equipment and the main power source and can provide back-up power for a limited amount of time, although an increased power consumption can decrease total time.

UNIT 2. EXTERNAL MULTIPLEXING EQUIPMENT

Objective 2a: Interfacing External Multiplexing Equipment

  • Introduction:

    • SATCOM isn’t always point-to-point.
    • Missions may require complex configurations, like multiplexing aggregate inputs from multiple modems.
    • Example: configured in a “mesh” network where the terminal receives services from a Standardized Tactical Entry Point (STEP) site and delivers those same services to another physically distant terminal.
    • External device for the GMT is the Nodal Satellite Multiplexer (NSM), also referred to as the Enhanced Tactical Satellite Signal Processor (ETSSP).
    • The information is designed to help the operator/user better understand the operation of the NSM.

  • Nodal Satellite Multiplexer-50 (NSM):

    • Function:
      • Synchronous time division digital multiplexer used in a satellite earth terminal.
      • Provides a full duplex capability in interfacing the modem in the terminal radio equipment with ground equipment.
      • Inputs from synchronous data users and digital non-secure/secure voice orderwire are multiplexed into a single output aggregate and supplied to the modem in the terminal radio equipment for transmission.
      • Received aggregates are demultiplexed into their composite parts and supplied to the respective data users and digital non-secure/secure voice orderwire.
    • Operation:
      • Operates at a maximum data rate of 52<br/><br/>Megabits per second (52Mbps)52 <br />\newline <br />\newline \text{Megabits per second (52Mbps)}.
      • Provides 12 Non-Return to Zero (NRZ) ports (Red), 6 T1/E1 ports (Green), 2 High-Speed Serial Interface ports (Orange), and 6 Conditioned Di-phase ports (Blue) for a total of 26 ports.
      • Only 12 total ports can be used in a single configuration.
      • Supports point-to-point, hub-spoke, mesh, and hybrid nodal configurations.
      • The port router handles the movement of data from ports to the multiplexer channels and from demultiplexer channels to ports.
      • The port router functions as an electronic patch panel.
    • Monitor and control:
      • Accomplished through an RS-232 connection that routes into a configuration computer.
      • For use in the GMT, monitor and control is handled through the same Control, Monitor, and Alarm (CMA) Graphical User Interface (GUI) that connects the rest of the subsystems throughout the terminal.

UNIT 3. TRANSMIT AND RECEIVE SYSTEM CHARACTERISTICS

Objective 3a: Transmit and Receive Systems

  • Introduction

    • Critical to ensure signal transmission through all phases (modem, block up converter, amplifier, satellite).
    • Knowing signal flow helps troubleshoot issues efficiently.

  • Transmitter

    • Modem modulates data into an Intermediate Frequency (IF) after receiving it from the DTE.
    • Parameters include frequency band, modulation types, and data rate.
    • IF is passed to the block up converter for translation into a usable radio frequency.
    • Final stage is amplification at the high-power amplifier (HPA).

  • Block Up Converter

    • Translates the IF from the modem to a usable satellite radio frequency.
    • Provides variable attenuation to control total power output.
    • Conveys the transmit signal to the amplifier through a coaxial cable.

  • Amplifier

    • High-powered amplifier (HPA) amplifies the radio frequency to reach the satellite and provide adequate signal strength for the receiving terminal.
    • Commonly used is a Traveling Wave Tube Amplifier (TWTA).
    • TWTAs contain vacuum tubes that radio frequencies pass through; as the tube heats, it amplifies the signal’s strength.
    • Other types of amplifiers include Solid State Power Amplifiers (SSPAs) and Klystron Power Amplifiers (KPAs).

  • Receiver

    • Receives a downlink radio frequency from the assigned satellite.
    • After entering the feed horn, the radio frequency is passed to a low noise amplifier (LNA).
    • Translated back to an IF at the block down converter.
    • The IF is then passed to the modem for data extraction.

  • Low Noise Amplifier

    • Ground terminals often receive a weak downlink signal from the satellite (ranging from −140-140 to −70-70 dbm).
    • The LNA amplifies the signal without degrading the signal-to-noise ratio.

  • Block Down Converter

    • Frequency translation, converting the downlink frequency into an IF.
    • The IF is then sent to the modem for data extraction.

UNIT 4. GLOBAL POSITIONING SYSTEM RECEIVER

Objective 4a: Global Positioning System (GPS) Receiver

  • Introduction:

    • The timing Line Replaceable Unit (TRAK 9000) provides stable timing throughout multiple systems in the GMT (located in electronic case B/E).

  • Capabilities:

    • Each hub has a dedicated timing unit, allowing independent operation.
    • Supplied with a GPS Stratum-1 timing source using a highly stable rubidium oscillator.
    • The rubidium oscillator provides a reference output of 5 MHz distributed through four (4) output ports.
    • The ETSSP (A), data modems (B), Replacement Frequency Modulated Order Wire (RFMOW) modem (B), the block up/down converters (C) and the KA-Band controller (D) all receive timing from the Stratum-1 timing source via the four (4) 5 MHz outputs.
    • Expansion card houses an internal battery that stores GPS Almanac data for quick satellite detection and communication.
    • Connects to an external GPS antenna for pulling timing information from GPS satellites.

  • Limitations:

    • If the internal battery fails, it will lose all GPS Almanac data.
    • This will cause longer tracking time for the GPS Satellites that the unit communicates with, but unit will still work.

Objective 4b: Global Positioning System (GPS) Receiver’s Controls and Indicators

  • Introduction:

    • Importance of knowing the role of each component in RF Transmissions.
    • Focus on the timing reference for the Ground Multiband Terminal (GMT), the TRAK 9000A Modular Time Code Processor, and its controls and indicators.

  • Front Panel:

    • Display:
      • Time of Year (TOY): Displays the current day of the year (1-365) and the Coordinated Universal Time (UTC) or local time (hour:minute:second).
      • Alphanumeric: Two (2) lines of 16 characters Vacuum Fluorescent Display (VFD). Features Status screens for monitoring and Setup screens to change parameters.
    • Keypad:
      • 18-key keypad with numbers 0-9 and control keys (STAT, NEXT, PREV, MENU, SEL, ENT).
      • STAT: Places display in status mode, navigated with NEXT and PREV keys.
      • NEXT: Scrolls to the next screen in Status, Setup, or module list screens; allows viewing setup screens without modifying setup.
      • PREV: Scrolls to the previous screen in Status, Setup, or module list screens.
      • MENU: Places the Mode Setup screen on the Liquid Crystal Display (LCD), allowing SELection and ENTRy of the desired operating mode.
      • SEL: Scrolls data through available choices on some Setup Screens.
      • ENT: Enters selected data.
      • 0-9: Selects a module for setup after pressing MENU.
      • ←→: Moves the cursor for data entry or corrections in a Setup Screen.

  • Rear Panel Ports:

    • EXT STD: BNC Connection for external 1, 5, or 10 MHz timing source.
    • 1 PPS OUT: Primary system output.
    • 5 MHz Outputs (4): Primary output for timing reference.
    • RS-232A: Remote setup and monitoring, including time output for connection to a remote computer or terminal.
    • RS-232B: Output status data to printer or terminal.
    • STATUS: Provides a signal if any fault is detected.

UNIT 5. ANTENNA AND TRACKING SYSTEM CHARACTERISTICS

Objective 5a: Antenna and Tracking Systems

  • Introduction:

    • Most antennas have satellite tracking to continuously peak on the satellite’s beacon with minimal drifting.
    • Without tracking, operators would constantly adjust terminals to maintain a nominal signal-to-noise ratio.

  • Antenna Systems:

    • Small Aperture Antenna (SAA):
      • The AN/TSC-179 system contains a Small Aperture Antenna.
      • 2.4-meter (8ft) dish with an offset feed.
      • Operates in all four bands (C, X, Ku, Ka).
      • Consists of an aluminum support structure, reflector center hub, eight (8) reflector panels, and four (4) backplane struts.
      • All reflector panels are calibrated by the manufacturer, so damage necessitates replacing the whole antenna.
      • Each band has its own feed horn and LNA mounted on the feed boom.
      • Tri-Band HPA must be mounted to the feed boom for C, X, Ku Bands; the HPA must be changed out for Ka-band use.
    • Large Aperture Antennas (LAA):
      • Q-LAA (Quad Band Large Aperture Antenna):
        • 3.9-meter (13ft) Quad-Band Large Aperture Antenna.
        • Completely self-contained transit (transport) case-based antenna subsystem.
        • Capable of non-simultaneous operation in the C, X, Ku, and Ka frequency bands.
        • Equipped with all interfaces and control capabilities to support continuous AN/TSC-179 GMT operations.
        • Contained in nine (9) ruggedized transport cases weighing a total of 1,862 pounds.
        • The GMT hardware integration kit is contained in four (4) additional transport cases weighing a total of 652 pounds.
      • LAMDA (Large Aperture Multi-Band Deployable Antenna):
        • 4.9 meters (16ft) diameter and operates over C-, X-, and Ku-bands.
        • Operates worldwide with spacecraft of the Defense Satellite Communications System (DSCS), DSCS III, North Atlantic Treaty Organization (NATO), NATO IV, and Skynet.
        • Includes a Tri-band HPA, X-band LNA, waveguide, and mounting brackets.
        • Requires 3-4 personnel to set up and tear down and can take 45min to 1 hour.
      • LHGXA (Lightweight High Gain X-Band Antenna):
        • Commonly referred to as the Trailer Mounted Antenna (TMA).
        • 4.9 meter (16ft), offset fed, trailer mounted, high gain, X-band antenna.
        • Requires 3-4 personnel to set up and tear down and can take 45min to 1 hour.
      • OE-361 QRSA (Quick Reaction Satellite Antenna):
        • Trailer mounted, 6.1 meter (20ft), center fed, high gain, X-band antenna.
        • Requires 6-8 personnel to set up and tear down and can take up to 1 to 2 hours.

  • Acquisition and Tracking Principles:

    • OpTrack:
      • Primary tracking mode, storing azimuth, elevation, and polarization.
      • Uses geosynchronous satellite data gathered during step track to form an ephemeris model.
      • Predicts satellite location in the event of signal loss.
    • Step Track:
      • Moves antenna to the initial satellite location and searches for any signal that breaches the established signal threshold.
      • If a strong signal is found, the antenna will begin to step track (hill climb) looking for the strongest signal.
      • If no signal meets or exceeds the threshold, the antenna will complete a box scan and step track (hill climb) to the highest signal found.
      • If no signal is found after the box scan, the antenna will give an indicator, “NO SIGNAL FOUND,” and return to the initial satellite location.
    • Position Track:
      • An enhanced version of Optrack.
      • Enters initial azimuth, elevation, and polarization of the satellite, and the antenna will jog to set position.
      • Once it reaches the set position, it will begin an optrack or step track.
    • Geo Track:
      • An enhanced version of Optrack, with the same concepts as position track.
      • Enters the geostationary satellite’s latitude and longitude instead of azimuth and elevation settings.
      • Once it reaches the set position, it will begin an optrack or step track.
    • Memory Track:
      • Works off the concept that geosynchronous satellites maintain a consistent rotation daily, which allows a record of the satellite’s position to be stored.
      • After enough stored memory is acquired, the antenna will repeat its tracking principles day by day.

UNIT 6. SITE SETUP

Objective 6a

  • Calculate satellite look angles using specialized tools IAW AETC Form 98, Student Progress Checklist.
  • Safety Review safety measures and prepare for performance.
  • Procedure
    • Using provided slide rules, explain/demonstrate how to use a slide rule to determine azimuth and elevation to a satellite IAW Module 9 Obj 6a Lab Procedures.
    • Evaluate student performance using Local Form 98.

Objective 6b

  • Establish a Master Station Log (MSL) IAW AETC Form 98, Student Progress Checklist.
  • Safety Review safety measures and prepare for performance.
  • Procedure
    • Explain what a Master Station Log is and why it is used.
    • Explain/demonstrate how to fill one out and evaluate student performance using Local Form 98.

UNIT 7. MULTIBAND SATCOM TERMINAL CONFIGURATION AND OPERATION

Objective 7a

  • Configure a multiband satellite terminal and establish satellite communications IAW AETC Form 98, Student Progress Checklist.
  • Safety Review safety measures and prepare for performance.
  • Procedure
    • Explain/demonstrate/perform equipment setup, configuration, and operational checks IAW Module 9 Lab Book
    • Evaluate student performance using Local Form 98.

UNIT 8. MULTICHANNEL SATCOM TERMINAL TROUBLESHOOTING

Objective 8a

  • Given Equipment and operating instructions, troubleshoot a multiband satellite terminal IAW AETC Form 98, Student Progress Checklist.
  • Safety Review safety measures and prepare for performance.
  • Procedure
    • Explain/demonstrate how to troubleshoot the system.
    • Identify the problem(s), fix the problem(s) and establish a satellite link IAW Module 9 Lab Book.
    • Evaluate student performance using Local Form 98.

UNIT 9. SATELLITE ROUTER OPERATIONS

Objective 9a

  • Given equipment and operating instructions, interface a multiband satellite terminal with an IP Network IAW AETC Form 98, Student Progress Checklist.
  • Safety Review safety measures and prepare for performance.
  • Introduction
    • Up to this point, we have been teaching you how to build FDMA circuit networks or a Single Channel Per Carrier (SCPC) network.
    • These networks work well for simple point-to-point connections and are cost-effective when you only have one distant end.
    • But what if you have multiple distant ends? What if there is not enough bandwidth available for the frequency band you want to use?
    • One solution is to use TDMA networks over SATCOM.
    • TDMA networks work by having multiple satellite modems time the release of their information using the Internet Protocol commands in a network hub.
    • Using only two frequencies or carriers, we can reduce our bandwidth consumption.
    • By reducing our bandwidth, the satellites overall capacity is increased.
  • In this lab, you will be introduced to a TDMA satellite router produced by a company known as iDirect. This satellite router will interface your users directly with Ethernet to our SATCOM terminal with no need for extra equipment. The Ethernet connection out of the satellite router can be plugged directly into a switch and configured as needed to support mission or user needs.
  • Procedure
    • Explain/demonstrate equipment setup IAW Module 9 Lab Book
    • Evaluate student performance using Local Form 98.