SATCOM in a box
COMPLETE SATELLITE COMMUNICATION SYSTEMS IN SMALL, PORTABLE CASES ARE A MAINSTAY OF SOF EARLY ENTRY OPERATIONS.
Flyaway and expeditionary terminals are designed for a clear early entry capability whether that is suitcase-size or larger. Embedded in their modular architecture is also an inherent capability to grow the terminal in parallel to the mission requirement, remaining sufficiently robust to meet users’ long-term requirements while deployed.
THE PROBLEM
In the flyaway class and larger expeditionary class of SATCOM terminals, pushing below 1 meter (m) aperture has self-evident benefits for deployability, if the required level of performance can be maintained. Current technology is making this easier to achieve.
Traffic modems, both single channel per carrier (SCPC) and time division multiple access (TDMA) now incorporate significant technology improvements in the level of turbo-coding and forward error correction, which allow users to close links using much lower power requirements. This, explained Brad Majeres, general manager for General Dynamics SATCOM Technologies, has significant implications, “A key limitation in sub-1m aperture terminals is the off-axis emission requirement mandated by regulatory agencies to limit possible interference with adjacent satellites. The pure physics at these smaller antenna sizes limits how much power you transmit. In the U.S., many satellites are just two degrees apart and with a smaller aperture, you can easily ‘interfere’ with another satellite unless you manage the transmit power and maintain pointing properly. If you are transmitting less power, then you are less likely to interfere with adjacent satellites or interfere with other sources.”
The space segment is playing its part too with higher power satellites being deployed enabling greater sensitivity so that ground-segment transmit power can be further reduced. Work to develop advanced tracking techniques for SATCOM on-the-move (SOTM) terminals to ensure precise pointing and signal lock under diverse dynamic conditions is also being ported for static use, again allowing a more accurate link to the satellite, further reducing potential interfaces.
The migration of the satellite communication marketplace toward Ka-band frequency operation also allows the use of much smaller antennas. Majeres said, “The recently launched WGS satellite and other near future ka-band satellites, accommodate larger bandwidths, increased capacity, and allow much smaller aperture terminals at Ka frequencies.”
Although technology advances with SCPC and TDMA have continued to reduce ground segment sizes, interoperability issues among various SCPC or TDMA modems still remain. An open standard for interoperability has been established for SCPC modems, (i.e., MILSTD 188-165A). However, in the TDMA arena, interoperability is still an issue because an open standard has not been established and many of the TDMA access solutions utilize a unique proprietary network access scheme and often employ different turbo-coding techniques.
“AvL Technologies is an antenna manufacturer that was a pioneer in the SATCOM-in-a-box technology by being the first to introduce high quality antennas with one-button auto-acquisition of satellites, said Jim Oliver, AvL’s president and CEO. “This immediately allowed any warfighter whether in communications or not, to benefit from broadband connectivity for a variety of purposes.”
AvL has supplied vehicular and flyaway antennas from 2.4 m down to 90x66 cm for a vast array of system integrators like General Dynamics, GCS and ViaSat. With the substantial improvement of satellite communications technology since its first use for the military beginning in 1985, smaller aperture antennas now can produce the same results with margins that use to require a 2.4 m aperture. Today a 2 m aperture can produce, at C, X, Ku bands, equivalent link margins to that of a 2.4 m in 1990s. “The real advantage of a 2 m over a 1.8 m is that it can be used in a 2 degree satellite spacing environment where a 1.8 m cannot,” said Oliver.
WARRIOR
To meet flyaway and SOTM requirements, General Dynamics has developed the Warrior family of terminals. The variants include SOTM, transit case, trailerized and skid-mounted satellite communication terminals. The smallest terminal, the Warrior 90, has a 96 centimeter aperture and is a lightweight, airline checkable transit case-deployed terminal.
The Warrior family of products has an auto-acquire (or auto-tracking) antenna control unit, common monitoring and control system and integral spectrum analyzer giving each terminal the same look and feel across the full Warrior terminal product family. The benefit to the user and support personnel is a consistent platform that simplifies operations and training. Majeres said, “The Army and USMC have worked with us to finetune our auto acquisition algorithms to the point where it is a quick, step-by-step process. All that users have to do is point it toward south and activate the autoacquisition process. Users don’t need to do a lot of testing and diagnostics in order to immediately and accurately establish a link to the desired satellite.”
General Dynamics has won two recent contracts for its Warrior terminals: The U.S. Army’s Joint Network Node (JNN) Lot 10, now known as Increment One of the Warfighter Information Network-Tactical (WIN-T), and the U.S. Marine Corps’ Support Wide Area Network (SWAN) programs.
The Army’s requirement is for two types of terminals. The first type, in potential quantities up to 1,200 units, is a trailerized 2.4 m satellite transportable terminal (STT), which is a self-contained, fully integrated satellite communications terminal that can be towed by an uparmored HMMWV. “It is primarily used for Ku-band voice, data, and video teleconferencing,” said Majeres. “In addition, operation in other bands such as Ka-band and a troposcatter communications kit are available for use with this terminal. The second terminal is a larger unit hub satellite terminal [UHST], mounted on a government-furnished FMTV. This terminal is equipped with 3.9 m antenna and fully integrated hub station TDMA and SCPC network access solutions that will interoperate with STTs currently in the theatre of operations.”
Delivering the JNN Lot 10 STT solution required internal research and development investment by General Dynamics. “We incorporated several new developments such as a higher-level tracking approach for this terminal in order to make it lighter and more capable,” explained Majeres. “It also features a true online UPS power system to provide true, stable, clean power regardless of the condition of the source power.”
The USMC’s SWAN is similar in overall application but it uses three terminal classes. Majeres explained, “The first variant is our 1.2 m Warrior 120 terminal, which uses an automatic acquisition controller that features the full M&C, spectrum analyser, and antenna control systems mentioned above. It is a tightly packaged complete terminal that integrates transmit-and-receive electronics along with the antenna and antenna controller, voice and data router, encryption equipment and UPS into lightweight, easily transported cases.”
The second terminal is the 1.8 m variant, the Warrior 180. It is identical to the 1.2 m terminal except it features the larger 1.8 m antenna. The third variant is the legacy 2.4 m STT terminal that has been supplied to the Army under their JNN Lot 9 contract. “The Marines wanted their solution to be interoperable with the Army and we are seeing more combined Army and USMC initiatives,” explained Majeres. The JNN Lot 9 STT terminal is being sourced by General Dynamics through its subcontractor DataPath, Inc.
Looking to the future, Majeres commented, “We are continuing to develop various products and solutions for flyaway and SOTM applications. This includes incorporating improved SCPC circuitry and TDMA network access solutions, adding more sophisticated step tracking capabilities and adding more sophisticated uplink and power controls into these terminals.”
VIASAT
“We are the largest supplier of Ku modems to the U.S. military with 3,000 LinkWay modems having being ordered. We also have what we consider to be the broadest modem product line in single band Ku and Ka band,” explained Mark Schwene, director strategic initiatives, government satcom systems at ViaSat.
Two modem families are offered, the LinkStar system for hub spoke systems and LinkWay system for mesh networks. Both of the products are being upgraded to DVB-S2. The upgraded LinkWayS2, is now in production with orders for the military version having been received.
“DVB-S2 is the real key because that is going to dramatically improve data rates. LinkWayS2 is 40 percent more bandwidth efficient than conventional Reed Solomon systems,” Schwene said. The LinkWayS2 terminal offers users a choice of carrier rates from 156 Kbps to 5 Mbps in 156 Kbps steps.
Some economies of scale are being driven-by commercial success with Via- Sat currently delivering 20,000 small low-cost terminals per month for the commercial WildBlue Ka band network.
Schwene said, “Because we are the leading commercial provider of the systems, we have applied that knowledge to military problems. A number of different military networks out there use either LinkStar or LinkWay satellite networks for a range of applications with the biggest being JNN terminals, which use LinkWay modems, including the most recent Lot 10.”
Schwene said that ViaSat VSAT equipment is in several different DoD networks. These include the Coalition Military Network, U.S. 6th Army in Korea, Joint Combat Camera, Stryker, Progressive Response Team, and the Army’s 3rd and 4th ID.
As well as modems, ViaSat also offers complete systems. This includes the LinkWay or LinkStar Ku band IP satcom flyaway terminal which uses a full-mesh self-acquiring 1.2 m dish in three transit cases which weigh 134 Kg including baseband, pedestal and antenna.
L-3 GCS
L-3 GCS received a competitively-bid contract for USSOCOM’s Special Operations Forces Deployable Node-Medium (SDN-Medium) Very Small Aperture Terminal Radio Frequency (VSAT RF) program in March 2006. This was won using a two-terminal solution explained Daniel Brooks, now a sales manager for L-3 Communications, which acquired GCS in May 2007.
“SDN is our sub one meter terminal, which we call the Cheetah, and the 1 m Hawkeye. They are Ku-band systems utilizing an iDirect modem, and the terminal is ruggedized to MILSTD 810F. “It’s perfect for the non-communicators who have a VSAT system but aren’t able to take a signal person or contractors out with them to operate it.”
The specifications for SDN-Medium required considerable work toward getting the commercial off-the-shelf items ready as Brooks recounted. “It has been going very well with deliveries that began in 2006. However, it was definitely a challenge getting the COTS components up to the rugged specifications required by USSOCOM. We put in some really large temperature chambers to allow it to operate in very low and very high temperatures during the 100-hour burn-in test.”
Work on SDN-Medium continues to meet rolling requirements. This is primarily driven by the need to upgrade to add Ka operations. Brooks said, “We are working on the Ka element now. Assuming everything goes to plan, Wideband Global SATCOM (WGS) will be operational as early as 2009. As soon as they are ready, we will be ready.”
Discussing what Ka band operation will mean for flyaway antennas, Brooks believes that similar performance to today’s Cheetahs at 0.9 m antenna could easily be achieved with a 0.6 m solution, although this would be dependent on a number of variables, not least that the terminal’s susceptibility to atmospheric condition would require increased power.
The acquisition of the privately-held GCS by L-3 has led to a burst of development work. Brooks said, “We have a lot of products in development, plus access to a range of products and the capabilities offered by other divisions, which has been a great asset. The first product to come out of development is a yet unnamed triband 1.6 m terminal offering Ku, Ka and X band.
A feature of the Cheetah is the addition of data port for L-band modems, allowing for future integration into the Army’s next-generation networks. This would allow for easy integration with Linkabit’s SCA 2.2-compliant MPM-1000 IP Modem, which is a standard on WIN-T. Irwin Morse, director, product management at L-3 Linkabit explained that the MPM-1000 has two uplink and four downlink channels, each channel capable of 256 Kbps to 3.12 G per channel. “It does on-the-move at 256 Kpbs to 512 Kbps and up to 3.12 Gbps per channel in a mesh network and features dynamic power handling on the fly.”
A number of users, including SDNMedium have adopted an iDirect modem, taking advantage of the company’s new TDMA spread spectrum capabilities. iDirect modems are being developed to provide an adaptive waveforms that will allow smaller terminals to be used on the same network. If a user wants to enter a network, adaptive coding in the iDirect modem will automatically switch the user to another waveform. This will result in a drop data, but the user will stay in the network.
SWE-DISH
“SWE-DISH has just launched its Communicase Technology (CCT), the latest in our line of ultra-portable, fast acquisition terminals,” explained Jim Gerow, vice president at Swe-Dish Satellite Systems AB, a DataPath company. This is designed not only for Ku but also to respond to the WGS satellite launches in support of Ka and X-band communications.
Gerow explained that SWE-DISH is expanding their product line, but within a coherent, scaleable family structure. “The CCT will be modular to our 0.9 m, 1.2 m, 1.5 m, and our fly-away and driveaway configurations. “With CCT we are establishing the means to provide early entry capability and then to be able to grow that terminal to meet longer duration requirements. In addition, we will be able to provide a crossover capability from fixed to mobile site communications. This new technology will be incorporated in our SOTM systems.
“CCT Technology creates one central intelligence, which is a base unit that has a cassette swappable modem function allowing the system to be used with i-Direct, Viasat, and Raydyne modems, for example. CCT intelligence recognizes each modem when inserted and automatically adjusts to changes in reflector size to achieve optimal performance. ♦