This video outlines updates from ORI's FPGA Projects meetup, focusing on digital communication advancements for amateur satellite and deep-space applications. Key project highlights include Aaron's integration progress on a DVB-S2 downlink for a satellite project, leveraging Everist's Pluto firmware and MQTT control. Pete discusses the development of a robust FSK waveform for the challenging two-way amateur communication with Venus (Project Eve), targeting the 2026 conjunction, emphasizing the need for advanced FEC codes due to extreme link conditions. The central discussion revolves around the "Opulent Voice" digital communication protocol, featuring an FPGA-based modem utilizing Minimum Shift Keying (MSK). The protocol aims for seamless multi-service communication (voice, chat, file) with prioritized voice quality, employing a layered architecture with custom headers, standard IP/UDP/RTP/TCP layers, and COBS framing, all implemented with modularity and accessibility in mind using Raspberry Pi and Pluto SDR.
Summarizing the FPGA Projects Meetup and "Opulent Voice" Protocol
0:00:14 ORI FPGA Projects Meetup Introduction: The session kicks off with an overview of the ORI FPGA Projects meetup, a collaborative platform for discussing progress, plans, roadblocks, and resource needs in FPGA-based amateur radio and space communication projects.
0:00:51 DVB-S2 Downlink Update (Aaron): Aaron reports on the integration of the DVB-S2 downlink for the satellite project. He has successfully implemented it on the Pluto SDR using Everist's firmware and is controlling it via MQTT commands. The immediate next steps involve generating expected data to test transmission and utilizing a BATC Picot tuner as the receiver.
0:03:00 Project Eve Waveform Design (Pete): Pete details his work on a practical FSK waveform for "Project Eve," which aims for two-way amateur communication with Venus during its 2026 inferior conjunction. He highlights the extreme challenges, including a very low link budget (-8.6 dB C/N0) and short coherent integration time (0.5 seconds), necessitating extensive non-coherent correlations and the development of robust FEC codes to achieve a usable bit error rate.
0:05:03 Advancing Communication with Venus: Michelle expands on Project Eve, emphasizing that the goal is to achieve actual information communication with Venus, a tougher challenge than the two successful radar signal bounces already achieved by the amateur community.
0:10:15 Introduction to "Opulent Voice" Protocol: The core of the discussion shifts to the "Opulent Voice" digital communication protocol. It utilizes an FPGA-based modem designed to convert bitstreams into Minimum Shift Keying (MSK), a modulation scheme chosen for its constant envelope, spectral efficiency, and common use in space applications.
0:11:36 Protocol Goals and Lab Progress: The protocol's primary goal is to provide a highly reliable uplink for amateur satellite use, as well as terrestrial point-to-point links and repeaters. It aims to integrate voice, chat, file transfers, and authentication/authorization into a single, seamless channel. The modem has been successfully tested over a local area network (LAN).
0:14:41 Priority System Optimization: An important design decision involved re-prioritizing data. Initially, authentication/authorization (A5) messages had the highest priority, leading to voice interruptions. The revised priority now places voice as the highest priority, followed by control messages, then chat, and finally general data, accepting a minor compromise where an unauthorized user might transmit one voice frame before being cut off.
0:17:03 Authentication & Authorization: The protocol incorporates security measures where each frame transmitted includes a claimed station ID and a 3-byte cryptographic token. This allows the receiving station (e.g., a satellite) to cryptographically verify the legitimacy of each frame, enabling flexible policy enforcement from open access to strict authentication.
0:20:42 Protocol Layering and Overhead Analysis: The system uses custom "Opulent Voice" headers in conjunction with standard internet protocols like IP, UDP, and RTP (for voice) or TCP (for chat/file data). While this adds some overhead, the developers believe the benefits of using well-established, time-tested layers (application compatibility, defined structures) significantly outweigh the perceived "baggage."
0:26:36 Efficient Framing with COBS: Constant Overhead Byte Stuffing (COBS) is used as the framing protocol. It's chosen because it provides consistent and low overhead (typically 1-2 bytes per packet), making it more efficient than traditional byte stuffing methods (which can reach nearly 100% overhead in worst-case scenarios). A VHDL implementation of COBS using AXI streaming has also been developed.
0:30:20 Forward Error Correction (FEC): While the current lab prototype doesn't include FEC, the planned protocol will use Golay encoding for the custom headers and Viterbi encoding for the payload, standard choices for VHF/UHF/microwave channels. The team is still determining whether the Raspberry Pi (framer) or the modem (FPGA) will handle the FEC processing.
0:32:27 Feature Demonstration & Modularity: The team has demonstrated seamless audio over LAN, with queued chat messages transmitting automatically after voice, and queued file transfers following chat. The system is designed for modularity, allowing the user interface/framer (on Raspberry Pi) to be separated from the remote radio/modem via Ethernet. It supports both command-line and HTML5 web interfaces for broad accessibility.
0:34:19 Target Voice Bit Rate: The Opus voice codec is configured to operate at a fixed rate of 16 kilobits per second, ensuring excellent voice quality.
0:37:17 Future Optimizations (Variable Bit Rate): Future plans include exploring the use of Variable Bit Rate (VBR) Opus, which can save bandwidth during silences in voice communication. This could allow for embedding chat or other data during these periods.
0:41:18 Frame Timing and User Experience: All data transmissions adhere to 40-millisecond frame boundaries. While this means a voice transmission might wait briefly to align with the next boundary, the team deems this acceptable for a consistent user experience.
0:42:58 Low Barrier to Entry for Testing: The protocol is designed to be easily testable, requiring only a Raspberry Pi 4, a computer for reception, a USB headset, and simple Python scripts, encouraging broad citizen science participation and "torture testing."
0:46:01 Development Philosophy and Target Hardware: The project adopts an iterative build-and-test methodology, rigorously challenging its own assumptions. The Pluto SDR is the target for the modem due to its power, availability, and cost-effectiveness within the open-source community.
0:48:50 Modular Modem Design: The modem is developed in VHDL for FPGAs using a modular design that leverages Git submodules, allowing flexible construction of transceivers from various components.