Optimized Radar Signal Processing for a Low-cost, Solid-State Airborne Radar

This work intends to provide a roadmap from the current commercial airborne solid-state weather radar such as the Garmin International's GWX-70 radar to future multi-functional, low-cost hazard avoidance radar that has greatly improved transceiver performance and is capable of providing airborne hazard sensing operations on a variety of platforms, including unmanned aerial vehicles (UAV). Currently, the airborne solid-state radars have made significant progress in term of C-SWaP (Cost, space, weight and power), while there are still many areas can be explored which, will result in game-changing new capabilities and new products down the road. For example, the in-depth knowledge of Doppler spectrums can be used to explore more airborne weather hazard information, and dual-polarizations can be used to discriminate different hazard types. The fundamental challenges of solid-state weather/multi-functional radar, on the other hand, originate from several issues including range and antenna sidelobe interference, transceiver nonlinearity, and requirement of precise calibrations. A new set of solutions based on advanced while efficient signal processing technologies are introduced in this work.

On the aspect of fundamental transceiver optimization, an adaptive pulse compression algorithm as well as its real-time implementation is being developed at the University of Oklahoma, which takes the existing matched filter outputs from radar FPGA and effectively mitigate any range and antenna sidelobes to below the noise floor, thus greatly enhance the accuracy of reflectivity/weak target estimation without affecting the existing hardware configuration. An extension of this technology allows the transmitter to operate closer to the compression point and mitigates the risk of the nonlinear distortion, thus the radar sensitivity can be improved to enable more advanced sensing techniques. This technology is being tailored to implement on Garmin's radar processing in real-time. Another important topic is the new processing algorithms that enable precise dual-polarized target observations with limited radar aperture size (which is less than 18 inch for the current system).

These new technologies are further promoting the operational application of airborne solid-state radar. we are able to collect a database of severe weather signatures with GWX radar and are performing off-line processing as enhancement and case analysis. The capability of track-while-scan (TWS) is also being demonstrated through flight test experiments. Sample results and data of these operations will be presented.