Ultra Low Power (ULP) Timing Circuit

escPNT™ is a commercially available, low SWaP-C (<6oz, ~3in x 4in) PNT solution that leverages patented, multi-sensor data fusion to provide highly accurate positioning in GPS challenged/denied environments. escPNT™ is designed to take advantage of any/all sources of position and timing information to derive a resilient, and accurate position. The base product utilizes external data sources that include 3 GNSS receivers, EO/IR data, odometry (for ground vehicles), cellular data and Real-time Kinematic (RTK) corrections. On-board sensors include a crystal clock, accurate Inertial Measurement Unit (IMU), barometer, and temperature sensor.  Our robust technology roadmap has been designed to continuously add reliability, accuracy and robustness for our existing customers and reach additional commercial and government markets. As an example, we are currently adding the use of LEO satellite signals (US Air Force LCMC Phase 2 SBIR) and Network PNT capabilities (US Army SBIR Phase 1), to enable accurate PNT in total GPS denial.   In general, we have found that absolute time and time management are critical to any PNT solution. However, commercially available real-time clocks do not have the combination of accuracy, holdover time, power, and cost needed to provide the low SWAP-C characteristics required. To remove this barrier to implementation and provide affordable, long-lasting, accurate PNT in GPS-denied environments, esc Aerospace has partnered with researchers at Northeastern University to create the Ultra-Low Power (ULP) timing circuit.  This circuit improves on previously published work to digitally compensate the oscillator for temperature variations. Preliminary estimates indicate that this approach can improve oscillator precision from the 3,000 parts per billion (ppb) by a factor of 20 to the 100-ppb level. Importantly, this circuit would have a power demand as low as 1 µW, equivalent to the standby power demand of contemporary automotive real time clocks, but 30 times more precise. This would allow the current escPNTTM to go from the current maximum holdover time of 50 minutes to 24 hours with virtually no increase in SWAP.