CRONUS

The overall goal of Ziva’s Phase II SBIR CRONUS proposal is to demonstrate the feasibility of a novel and powerful approach to wirelessly distribute Two-Way-Time-Transfer (TWTT), ranging, and a frequency reference amongst distributed nodes.  The developed radio waveform will be capable of ultra-high accuracy ranging in the 10’s of picoseconds and frequency transfer of 1e-11 accuracy independent of GPS satellite systems and other GNSS signals which are vulnerable to jamming and/or spoofing.  Ziva proposes to exploit its demonstrated <10’s ps level wireless phase synchronization and TWTT based on RF Time Reversal. This approach will be extended in Phase II to ameliorate the bias errors due to multipath effects.   Under Phase II CRONUS, Ziva will create numerical models for the CRONUS signal processing subsystems, including two-way time-transfer and ranging to predict subsystem as well as entire-system performance.  Ziva will create a channel model able to emulate channel multipath and noise and develop a radio hardware model able to emulate biases due to radio group-delay variation, as well as PLL phase offset.  These subsystem modules will be used to create an overall CRONUS system model.  The CRONUS system model with the channel model will be used to optimize system performance with emphasis on system calibration, and eliminating bias errors arising from channel multipath. Ziva will implement the optimized algorithms to reduce latency critical operations in the FPGA, and latency insensitive algorithms in software on the node CPU, or the analysis machine. A graphical command and display environment to calibrate, run, and collect data from the 3-node, 2-hop CRONUS wireless two-way time transfer system via a standard Ethernet networking.  The Ziva SDR nodes will be modified to accept and output PPS pulses, such that the frequency of the master node (and thus the entire 3-node CRONUS system) can be disciplined to that of GPS (or other GNSS).   Ziva will upgrade the Quad Mixer Time difference system developed in Phase I to measure time-offset to sub-picosecond time accuracy between 3 of the 100 MHz sinewave outputs from the nodes. Simulations will be backed-up with testing of the prototype to assess the TWTT and ranging accuracy of the proposed CRONUS system. Ziva will demonstrate the feasibility to achieve: a) Ranging with cm-level accuracy and TWTT with picosecond-level accuracy, and frequency transfer < 1e-11 accuracy.  Ziva will develop and demonstrate a multi-hop relay among three connected prototype radio nodes in a laboratory demonstration thereby expanding from a 1-hop star topology system to a multi-hop system, capable of offering multi-hop operation allowing for arbitrary system topologies that will be compatible with modern Mobile Ad-hoc Networks (MANETs).  Ziva will demonstrate < 10 cm of bias error outdoors in multipath with 3-node outdoor long-range tests