Sparse Array Applications for Small Satellites

The purpose of this program is to provide a technology that enables the deployment of constellations of satellite based, coherent, RF sparse arrays. Such sparse arrays would have higher resolution than conventional approaches and would provide superior remote sensing capabilities at a fraction of today’s cost. The key enabling mechanisms are 1) the ability to accurately measure the distance between individual satellites, and 2) the ability to distribute a coherent clock among satellites in a given constellation. The Phase 1 program conducted an early assessment of UWB technology to determine if it offered the basis to develop a coherent clock distribution system capable of supporting a 10 GHz sparse array. This assessment was performed by conducting both clock distribution and range accuracy tests. These tests employed our standard off the shelf UWB P210® platform in a static test configuration. The tests demonstrated that our standard UWB platform was capable of synchronizing clocks to within 5ps and ranging over hundreds of meters with an accuracy of a few millimeters (13.5mm standard deviation). Analysis of these encouraging results led us to conclude that additional platform development and optimization would lead to even better performance. Due to the promise of this technology and to ensure continuity with succeeding Phase II and Phase III efforts, Phase I concluded with the development of top-level mission and spacecraft system design requirements. The Phase II program proposes to optimize Time Domain Corporation’s (TDC) emerging P400p platform for use in a sparse array application. Multiple P400ps representing individual elements of a sparse array will be deployed in a series of static and dynamic tests conducted on an optical breadboard. The precision metrology provided by the optical breadboard will enable us to establish “truth” position data for comparison against the positions provided by the UWB system. This approach will allow us to verify that the system can provide the timing synchronization and position accuracy required to support a 10 GHz sparse array. In addition, we will engage a specific transition partner for a Phase III effort.