Speaker
Description
Experimenting with new modulation schemes on bespoke modem hardware is difficult without a high-throughput interface that lets the hardware act as a software-defined radio (SDR), streaming raw IQ samples to and from GNU Radio. Lacking such an interface, the only way to validate a transmitter/receiver chain is to exchange raw binary payloads between a pair of modems over a low-throughput link, editing the hand-written Python modulation script on the modem directly whenever a change is needed. This is workable but becomes a bottleneck during iterative development, and it assumes a fluency in DSP scripting that the FPGA and hardware engineers collaborating on our in-house modem — who often need only minor adjustments for validation — do not necessarily have.
Prior approaches to coupling GNU Radio with Zynq-based hardware fall into two broad categories. One accelerates individual DSP primitives in the programmable logic (PL) while GNU Radio runs on the ARM processing system (PS). The other tethers the SoC to a host PC over a network link to act as an SDR, streaming IQ over interfaces such as TCP or UDP. Our contribution combines the strengths of both: GNU Radio runs on-device, and custom Source and Sink blocks stream IQ samples directly between the flowgraph and a custom acoustic PL front-end via direct memory access.
We extend the software-defined underwater acoustic modem developed at Florida Atlantic University Center for Connected Autonomy and AI, built around the AMD/Xilinx Zynq-7020 SoC. We detail custom Source and Sink blocks that stream IQ samples between GNU Radio, running in PetaLinux on the ARM PS, and the PL, with the high-throughput data path carried by an AXI DMA engine over AXI4-Stream and configuration handled over a separate AXI4-Lite interface. The blocks expose NCO offset, bandwidth, sampling rate, and RX gain as parameters, effectively turning the modem into an on-device SDR driven entirely from a GNU Radio flowgraph. We further describe a deployment pipeline that takes a design from GNU Radio Companion on the desktop to a running flowgraph on the modem with minimal engineering effort, and discuss how this has accelerated our modem development while making the platform approachable to a broader range of engineers and researchers. We conclude with a demonstration of our modems exchanging modulated data using transmit and receive chains built entirely in GNU Radio.
| Talk Length | 15 Minutes |
|---|---|
| Acknowledge | Acknowledge In-Person |