This Open Research Institute (ORI) projects meetup covers significant progress and ongoing challenges across several FPGA and radio system development efforts. Erin reports a successful workaround for VHDL 2008 compatibility issues, enabling the porting of a DVBS2 encoder to the OpenCPI framework and generating a valid bitstream for a ZCU104 board. Paul announces a major breakthrough in resolving critical timing and latency gaps in the "Dialogus" software for the PlutoSDR, achieving a stable data stream to the FPGA modem. Michelle details the debugging of an MSK modem in simulation, which performs perfectly with internal PRBS data but fails with external data streams, leading to an investigation of the dual Costas loops beyond an initial "error starvation" theory. Finally, Rick shares updates from the EVE radio astronomy project, including troubleshooting data collection software for the galaxy drift scan and celebrating the successful detection of the faint and fast-spinning Crab Pulsar, which validates the performance of their radio telescope.
FPGA and Radio Systems Development Updates
00:00:26 DVBS2 Encoder Ported to OpenCPI: Erin successfully ported a DVBS2 encoder to the OpenCPI framework, overcoming build issues with VHDL 2008 by creating a Vivado design checkpoint and importing it as a primitive. He has successfully generated a bitstream for the Xilinx ZCU104 development board.
02:10 Next Steps in Encoder Integration: The next task is to write the logic to initialize the encoder's IP core, specifically the modulator's constellation registers, using an AXI4-Lite interface. This will bring the core online for active use.
06:01 Critical Timing Issues Resolved in PlutoSDR Software: Paul has fixed significant timing and latency problems in the "Dialogus" software, which feeds data from a network interface to the PlutoSDR's FPGA. The modulator requires a perfectly steady stream of data, and the previous software version was creating gaps in transmission.
08:25 Stable Data Transmission Achieved: The implemented software fix now ensures a frame is sent reliably every 40 milliseconds with less than 1 millisecond of uncertainty. This was verified using the "Mya" project as a high-speed spectrum analyzer, which confirmed the transmission gaps have been eliminated.
11:33 New Hardware for Advanced Debugging: To aid in troubleshooting, the lab has acquired advanced PlutoSDR clones (like the LibreSDR) that feature Ethernet ports and larger FPGAs, as well as a dedicated USB tracing device to analyze data flow.
19:53 MSK Modem Fails with External Data in Simulation: Michelle is developing a simulation testbench for the MSK modem. While the modem works perfectly with an internal pseudo-random (PRBS) data source, it fails to produce coherent output when fed with external data via the AXI streaming interface.
24:03 Investigating Costas Loop Behavior: The team initially suspected an "error starvation" issue in the modem's dual Costas loops. While a code change confirmed and fixed a problem where the loops were not updating simultaneously, the received data remains garbled, indicating a more complex underlying issue is present.
31:55 EVE Project Radio Astronomy Update: Rick is troubleshooting the galaxy drift scan data collection pipeline at the Haswell site. To determine if performance issues stem from hardware or software, he is comparing results from two different GNU Radio-based data collection and analysis packages (EZ and Virgo).
46:21 Major Success in Pulsar Detection: The team achieved a significant milestone by successfully detecting the Crab Pulsar. This is the fastest (33ms period) and weakest (550 mJy) pulsar the project has ever captured, serving as a powerful validation of the radio telescope's sensitivity and overall system performance.
01:03:09 Automated Network Testing: Paul is exploring the use of TCP Replay, an open-source tool that can play back captured network traffic (pcap files) to create a repeatable, automated test environment for the Dialogus software.