Ground tests confirm satellite communications for battlefield
Northrup Grumman recently verified the compatibility of the advanced extremely high-frequency military communications satellite with user ground terminals.
Greg Reed, Contributing Editor -- Test & Measurement World, 3/7/2008 11:37:00 AM
On February 1, Northrop Grumman announced that it had demonstrated the interface compatibility of the advanced extremely high-frequency (EHF) military communications satellite with user ground terminals. The satellite uses extended data rate (XDR) waveform and protocols, which allow it to provide more communications capacity and higher channel data rates than previous systems, according to the company.
The advanced EHF is a joint service satellite communications system that will provide global survivable and protected communications for high-priority military ground, sea, and air assets. Northrop Grumman's Space Technology sector is under contract to provide the communications payloads to Lockheed Martin, the prime contractor for the advanced EHF system.
The tests of the satellite were conducted using a US Army user terminal as well as a terminal configuration to be used by international partners participating in advanced EHF. I asked Scott Willoughby, advanced EHF payloads program manager for Space Technology sector, to shares his insights on the technology and the testing process.
Q: What is the military significance of EHF satellite communications and the role of user ground terminals equipped with XDR waveform protocols?
A: The advanced EHF satellites employ onboard data processing, advanced antennas, and protected waveforms to provide US military services and allies with protected satellite communications. “Protected” communications means that they are highly resistant to an adversary’s attempts to detect or intercept military space communications or to disrupt those communications by means of radio frequency jamming. This gives military users access to assured communications in environments where these types of threats exist, which actually is anytime they are operating in an area of conflict.
The XDR waveform is a secure, anti-jamming waveform developed for ground-to-satellite uplinks and downlinks. This waveform is an advancement from the low data rate (LDR) and medium data rate (MDR) waveforms currently being used for protected communications with the existing Milstar constellation of military communications satellites. The XDR waveform will enable data rates roughly six times than of the MDR waveform in use today.
Advanced EHF satellites provide yet another element of protection by using inter-satellite crosslinks that allow global terminal-to-terminal communications without the use of intermediate ground stations.
Q: Tests have verified capability for LDR, MDR, and now XDR waveforms. What capabilities are expanded with XDR waveform protocols?
A: Primarily, higher data rates. Advanced EHF satellites will provide 10 times more communications capacity and six times higher channel data rates than the predecessor Milstar II satellites because of the XDR capability and other advanced technologies. Higher data rates can support more data-intensive communications, such as real-time video, battlefield maps, and targeting data.
Q: What are some primary challenges for integrating advanced waveform protocols into existing Milstar terminals?
A: One of the primary challenges involves modifying Milstar terminals to be compatible with advanced EHF and XDR. Success in meeting these challenges can be credited largely to extensive experience developing and integrating these elements for protected military satellite communications over decades. These are very unique and complex systems for which the expertise and processes gained from past experience are invaluable. We are now preparing to bring this experience to future systems the US Air Force is planning, where we will apply the XDR waveform as well as implement yet another more advanced waveform called XDR+.
Q: Is there potential for equipping commercial systems with XDR technology?
A: Generally, no. The systems using XDR have special, very complex processors onboard the satellite to interface using these protocols. It is this processing capability that protects the communication function against adversaries. Commercial satellite systems are “unprotected” and do not have this type of processing onboard.
Q: Any further observations or comments?
A: Protected military communications are increasingly vital to support the men and women in the military services today. “Protected satcom” provides the underlying communications links that make resources like the “Internet on the battlefield” possible.
We are seeing an ever-increasing reliance on communications and connectivity in modern combat. The advanced EHF satellites, and the next-generation systems that will follow, provide a critical layer of protected, survivable communications that the war fighters and commanders can count on in a conflict situation.
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