Speaker
Description
Wirelessly coordinated coherent distributed antenna arrays (CDAs) provide a flexible alternative to fixed monolithic antenna arrays by allowing spatially separated radio nodes to operate cooperatively. This approach is attractive for sensing applications where a single fixed array may be costly, difficult to deploy, limited in aperture size, or vulnerable to a single point of failure. However, practical constraints still occur. Each software-defined radio (SDR) operates with its own clock and RF front end meaning each node must be coordinated precisely enough to support coherent processing. Furthermore, CDAs tend to be more sparsely distributed compared to traditional arrays. While many sensing methods rely on highly structured element spacing, Fourier-domain imaging techniques are generally more suited to sparse apertures.
In this talk, we present a fully digital, wirelessly coordinated distributed Fourier-domain imaging experiment implemented with commercially available SDRs and GNU Radio. The system builds on prior work in high-accuracy fully digital wireless coordination of time, frequency, and phase between SDR nodes, enabling coherent processing without dedicated external synchronization hardware. To perform the imaging, multiple receiver elements observe spatiotemporally incoherent broadband noise emitted from or scattered by a scene; this noise is collected and cross-correlated over many baseline pairs to form spatial frequency samples of the scene, either simultaneously in a large array, or accumulated over time by moving individual antenna elements. By accumulating samples from multiple baselines in the spatial frequency domain, the system may reconstruct an image via an inverse Fourier transform to return to the spatial domain.
We will focus on the GNU Radio runtime implementation and postprocessing software of this experiment, including the SDR control, synchronization, receive side signal processing, and the image reconstruction process. Experimental results will showcase how commercial off the shelf SDR nodes can be used for distributed coherent sensing using a two-element array to collect a diverse set of scene spatial frequencies to form an image over time. Additional focus will be on highlighting the practical challenges of moving from interferometric imaging theory to a working GNU Radio based system.
| Talk Length | 30 Minutes |
|---|---|
| Acknowledge | Acknowledge In-Person |