By Bob Mowry
Robert.mowry@tachyon.com

For years the SATCOM industry has worked to provide high-speed satellite based BLOS (Beyond Line of Sight) solutions for Intelligence, Surveillance and Reconnaissance (ISR) and other applications for both commercial and military markets with Full Motion Video (FMV) requirements. Thanks to advanced solutions in operation today such as Tachyon’s aXiom 9300, which can deliver multi-megabit speeds in both forward and return directions, this FMV capability exists for fixed wing aircraft.  Multi-megabit satellite network services have greatly enhanced the US Military’s ability to perform advanced ISR missions in the field. But unmet demand remains for a satellite broadband communications solution that can deliver BLOS FMV from a rotary wing aircraft.

So far, industry attempts to achieve the 768 Kbps or faster speeds necessary for high quality ISR video, have failed to overcome signal degradations due to shading by helicopter rotor blades.  In addition, proposed solutions often require significant aircraft modifications, costing time and money. To date, the fastest solution industry has to offer achieves link speeds of only a few hundred Kbps.

I believe we can do better than that.  The technologies exist to meet key requirements of today’s rotor blade customers, including:

• Ka, Ku, X and/or L band support.
• Operational while hovering or in full speed flight
• Communications techniques designed to mitigate the channel effects imposed by rotor blades
• Reliable real-time video transmission (from helicopter to ground station)
• High quality video imaging with high efficiency image encoding H.264
• Very small aperture antennas with excellent performance
• SWaP of less than 50 lbs. and 380 Watts
• Fully automated operation
• Auto tracking of satellite and polarization
• High antenna pointing accuracy under helicopter motion conditions of roll, pitch and yaw
• Interactive voice communication during video transmission
• FCC/ITU-compliance for commercial satellites and ARSTRAAT certification for WGS satellites
• Secure broadband IP network access
• Advanced network management

A technology-agnostic approach using best of breed products and platforms must be employed to build a system that meets the above requirements.  Various waveforms should be evaluated to gauge how effective they are in penetrating variable speed, spinning rotor blades.  Airborne antennas in multiple sizes and form factors must be considered to achieve the optimal balance between link performance and aircraft SWaP constraints.

Once a solution is designed and built to achieve the above requirements, testing the solution is no small feat.  Aircraft terminal performance testing must be performed at various link speeds and orientations to the rotor. Among other tests, transmission and reception of the SATCOM IP data rate must be measured, as well as RF link performance and efficiency.

Tachyon is tackling these challenges and will be testing systems in the coming months.  Stay tuned to Tachyon In Touch to find out what we learn and what kind of performance is available to our customers with rotary wing aircraft.