Technical note | Bistatic Radar Concept Demonstrator (BiRCD) System Development and Verification

In this report the development and verification of the Bistatic Radar Concept Demonstrator (BiRCD) system within the Surveillance and Reconnaissance Systems Branch (SRS) is described. The motivation for this project was to develop an experimental bistatic pulse Doppler radar capability where none existed, so as to facilitate research in support of science and technology objectives. The capability is anticipated to stimulate advancements in the detection of targets against the backdrop of clutter, which will contribute to enhanced situational awareness and decision superiority in complex battlefield environments. The project doubles as the author’s final year honours project for submission to the University of South Australia.

The developmental process followed is detailed; beginning with broadly defined objectives and culminating with the successful field demonstration of a functional bistatic radar system in May of 2018. The primary drivers of capability and requirements are identified; they include future integration with the second Experimental Phased Array Radar (XPAR-II) and research into bistatic characterisation of sea clutter.

Two bistatic nodes were built which utilise a software defined radio (SDR) based hardware platform with a custom L-band radio frequency (RF) front-end. The RF front-end was designed so as to compliment the SDR hardware and offers improved radar performance. Synchronisation between the nodes is accomplished through use of GPS disciplined oscillators. A user generated script file which is common to all nodes directs the deterministic scheduling of radar operations across all nodes. While all remote nodes have identical hardware and software, a unique identifier is referenced to the script file to direct node specific behaviour. The radar return is captured simultaneously on all nodes where it is stored for offline processing.

The use of SDRs as the hardware platform provides valuable exposure to this innovative technology. While SDRs provide great flexibility, development was less than straightforward; perhaps an indication of an immature product. Insights into their use are provided which may prove useful in informing future projects as to the advantages and disadvantages they afford. SDR hardware driver limitations were encountered as were the limitations of driving the radar from a non-real-time operating system.

A land based field trial was conducted which provided experimental validation of system functionality and performance. The accuracy of the system was compared against returns from a known target source yielding satisfactory results. Aircraft detections were confirmed by correlation against ADS-B data, demonstrating valid detections of aircraft up to the maximum unambiguous range of 19kms.

It is demonstrated that all capability requirements and scheduled project objectives have been met or exceeded. The system presently supports multistatic operation, requiring only the construction of additional nodes at reasonable cost. Future integration with XPAR-II will provide additional capabilities including electronic beam scanning and greater transmitter power. Future work may focus on continued development and expanded applications, making use of the flexibility provided by the SDR hardware solution, including instantaneous sample rates of up to 160Msps.