Session
Poster Session I
Event Website
https://www.smallsat.org/index
Abstract
This research is directed towards development of a chip-scale timing unit (clock) to be used in new systems that aim to improve the quantity and quality of data transmittal from small spacecrafts. The quantity and quality of data transmission are directly influenced by the speed and accuracy of the on-board clock. NASA roadmap identifies major technical challenges for space clocks using current technologies (i.e., quartz resonators), namely sensitivity to on-board thermal environment conditions and susceptibility to g-force, and ionizing radiation effects. The timing units developed under this project will enhance the current Small Satellites capabilities. With this technology Small Sats can make big contributions and pioneer an industry for future military, civilian, and commercial missions.
The proposed approach directly tackles the stated technical challenges by developing a chip-scale all silicon integrated clock that has 10x better frequency stability compared to quartz-based clocks and 100x lower acceleration sensitivity at 10x higher speed. It is based on a new generation of phonon traps/resonators that are both passively and actively compensated to reach unprecedented frequency accuracy and stability. The proposed timing unit is stable across a wide range of temperatures. Recent measurements from a CubeSat indicate a temperature variation of -40 to 120 degree C for solar panels in geo orbit. For the main instrument board, the temperature is controlled at -2 to -10 degree C using thermal insulation to maintain the thermal fluctuation at a minimum. Assuming the timing unit experiences a worst case temperature fluctuation of -40 to +40 degree C, the frequency output can be maintained stable to less than 2 ppb using a feedback control loop. To do so, the proposed system includes a single phonon trap that exhibits two modes with significantly different temperature coefficient of frequencies (TCFs). In the feedback control loop, the dual mode oscillator is phase-locked at a stable operating point, where the phonon trap resonator is heated to a desired oven-set temperature. The proposed performance cannot be obtained from any other current, or planned product, with a solution that offers high science value through a small-size (
The low SWaP of the proposed system makes it an ideal candidate for CubeSats of as small as one unit (1U) with size of 10x10x10cm3. The low weight of the proposed clocks is several orders of magnitude smaller than the total weight of 1U to 3U CubeSats (1kg up to 5kg total), and its power consumption is a negligible fraction of the total system power (1W up to 6W (3U)).
Included in
Miniaturized Phonon Trap Timing Units for PNT of Cubesats
This research is directed towards development of a chip-scale timing unit (clock) to be used in new systems that aim to improve the quantity and quality of data transmittal from small spacecrafts. The quantity and quality of data transmission are directly influenced by the speed and accuracy of the on-board clock. NASA roadmap identifies major technical challenges for space clocks using current technologies (i.e., quartz resonators), namely sensitivity to on-board thermal environment conditions and susceptibility to g-force, and ionizing radiation effects. The timing units developed under this project will enhance the current Small Satellites capabilities. With this technology Small Sats can make big contributions and pioneer an industry for future military, civilian, and commercial missions.
The proposed approach directly tackles the stated technical challenges by developing a chip-scale all silicon integrated clock that has 10x better frequency stability compared to quartz-based clocks and 100x lower acceleration sensitivity at 10x higher speed. It is based on a new generation of phonon traps/resonators that are both passively and actively compensated to reach unprecedented frequency accuracy and stability. The proposed timing unit is stable across a wide range of temperatures. Recent measurements from a CubeSat indicate a temperature variation of -40 to 120 degree C for solar panels in geo orbit. For the main instrument board, the temperature is controlled at -2 to -10 degree C using thermal insulation to maintain the thermal fluctuation at a minimum. Assuming the timing unit experiences a worst case temperature fluctuation of -40 to +40 degree C, the frequency output can be maintained stable to less than 2 ppb using a feedback control loop. To do so, the proposed system includes a single phonon trap that exhibits two modes with significantly different temperature coefficient of frequencies (TCFs). In the feedback control loop, the dual mode oscillator is phase-locked at a stable operating point, where the phonon trap resonator is heated to a desired oven-set temperature. The proposed performance cannot be obtained from any other current, or planned product, with a solution that offers high science value through a small-size (
The low SWaP of the proposed system makes it an ideal candidate for CubeSats of as small as one unit (1U) with size of 10x10x10cm3. The low weight of the proposed clocks is several orders of magnitude smaller than the total weight of 1U to 3U CubeSats (1kg up to 5kg total), and its power consumption is a negligible fraction of the total system power (1W up to 6W (3U)).
https://digitalcommons.usu.edu/smallsat/2016/Poster1/16
