Who is using C-Band for Flight Test Telemetry in the USA?
Few people go anywhere today without a small computer in their pocket that is tethered to a mobile wireless Internet connection. Heavy demand for mobile Internet led to the US Government to sell off parts of the RF spectrum to cell service providers. These L & S Bands are well suited to giving more bandwidth for mobile phone and tablets.
There is an issue for some other users of the RF spectrum however. Flight and missile test and launch services used the L&S Band to telemeter data from the aircraft to the ground. The US government have given some of the money it made from selling the rights to use the spectrum to various agencies to help them transition to using a different part of the spectrum – the ‘C-Band’.
Moving to a new RF Band is not as simple as turning a dial on some equipment. First, new equipment will need to be installed to replace transmitter, receivers, antenna and other ancillary ground station equipment. Second, operating in the C-Band requires more power – some aircraft tests have shown doubling the power is a good way to ensure the same level of transmission quality. There is also less room for data in the new band – moving to more efficient coding schemes should help with this though. Finally, there are some other challenges such as tracking antenna needing to be more precise.
With all these challenges, it is not surprising that it is taking some time for test ranges to make the transition to C-Band. There is more pressure to do this is densely populated areas as the L&S bands will be more congested leading to everyday operation of the flight test community being drastically affected with reduced operational availability due to increased frequency crowding.
Curtiss-Wright has conducted research to find out just where organizations are in the C-Band transition. The results of this are presented in figure 1. The green states are currently using the C-Band allocations, the yellow states are in progress of implementing C-Band, the blue states currently have no plans to transition while the purple areas have low population and have no great need as the auctioned bands are little used.
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