Stephen Pendergast’s Post

Global Coordination for #Hypersonic Missile Defense The DoD created #SpaceDefenseAgency #SDA in 2019 to build a constellation of missile transport and tracking #satellites in #lowEarthorbit on a rapid timeline, augmenting large spacecraft constellations with hundreds of relatively inexpensive small satellites. These spacecraft constitute what SDA calls its Proliferated Warfighter space architecture #PWSA and will serve as the foundation for joint and multi-domain command and control capabilities. Being able to tie the SDA PWSA in with air, ground, and naval tactical assets is important to the SDA concept to track #hypersonic missiles over the whole trajectory from orbit, and coordinate #interception using all existing assets. Since most of these assets are already tied in to a Link 16 #JTIDS network, this would be the most obvious path. Link 16 has been implemented by most units using a frequency hopping, TDMA architecture, sometimes with stacked nets using CDMA, over tactical areas roughly 2000 NMi square. Even Taiwan, using the PoSheng program, has been using #Link16 compatible radios. Satellite gateways have been used to route data beyond the tactical areas via point to point satellite links. Given the time critical nature of PWSA data, the satellites will need to participate directly in a JTIDS network as they fly over its tactical area. Why is this a Problem Link 16 is a military tactical data link used primarily by NATO and allied nations for secure and jam-resistant communication and data exchange between various platforms such as aircraft, ships, and ground forces. It operates in the L-band frequency range (969-1206 MHz), which is also used by civil aeronautical radio systems and Mode S transponders. There is a frequency notch for IFF at 1090 MHz. Spectrum is a valuable asset, and this particular RF spectrum is allocated to aeronautical navigation by the ITU worldwide. Useage by a satellite for earth directed transmission on a "not to interfere" basis is problematic. Solving this before it causes problems to Civil Aviation is critical. #Interference between #military Link 16 and #ICAO civil aeronautical radio and Mode S can occur due to several reasons: Frequency Overlap; Signal Strength; Spectral Interference; Jamming and Electronic Warfare: