This Open Research Institute (ORI) project meetup covers key technical advancements and strategic planning for several open-source communication projects. A major focus is on the Opulent Voice digital communication system, detailing a significant architectural shift from UDP to TCP for network encapsulation to ensure reliable frame delivery to remote SDRs. The team also addresses a critical web browser security challenge related to microphone access over non-local HTTP connections, proposing a companion helper application as a solution. Progress on the EVE (Earth-Venus-Earth) project's link budget analysis is reviewed, highlighting the performance limitations of M-ary FSK modulation due to short channel coherence times. Future development priorities are established, including the implementation of a conference server for Opulent Voice and a new focus on developing the Hyphaeria satellite's multi-channel FDMA receiver. The meeting concludes with a discussion of upcoming presentations and the announcement of an ARRL Technical Innovation Award for team member Matthew.
ORI Project Developments: Advancing Opulent Voice and Satellite Communications
0:30 Opulent Voice's Network Protocol Shift: To improve reliability over networks, the data encapsulation protocol for delivering frames to a modem (e.g., a remote SDR) is being changed from UDP to TCP. This addresses issues like packet loss and out-of-order arrival.
2:10 COBS for TCP Framing: Since TCP is a byte-stream protocol, a framing layer using COBS (Consistent Overhead Byte Stuffing) will be added to delineate individual packets. This change only affects the delivery to the modem and does not add overhead to the over-the-air protocol.
5:06 Solving the Browser Microphone Access Problem: Modern web browsers restrict microphone access over non-secure (HTTP) connections unless the target is localhost. To enable microphone use with a remote SDR without the complexity of a full HTTPS server, the team plans to create a small, local "helper application" that streams the user's audio.
22:59 EVE Project Link Budget Update: Analysis for the Earth-Venus-Earth link shows that while M-ary FSK modulation is a candidate, its benefits are eroded by the channel's short coherence time, which necessitates less efficient non-coherent averaging. The team will now investigate alternative modulations like transmit-reference spread spectrum.
27:06 Designing the Conference Server: The next major feature for Opulent Voice is a conference server. The design includes a self-cleaning list of available conferences that users can monitor or join by transmitting. The user interface will gain a new tab for managing conference interactions.
31:38 Upcoming Demonstrations and Presentations: The team will have an exhibit at Defcon's RF village and will be presenting their contributions to the future amateur radio GEO satellite project at the ESA/AMSAT-DL symposium in September.
34:14 Next Critical Focus: The Hyphaeria Receiver: The development of the Hyphaeria satellite's receiver is now a top priority. This component is crucial for receiving multiple simultaneous Opulent Voice FDMA uplinks and will require a sophisticated multi-rate polyphase channelizer.
42:59 Defining a Peer-to-Peer Mode: The team discussed adapting Opulent Voice for symmetric, peer-to-peer communications that do not rely on a high-bandwidth satellite downlink, making it usable in scenarios similar to simplex or local repeater operation.
48:44 Team Member Wins ARRL Award: Matthew was awarded the ARRL Technical Innovation Award for his foundational work on the project's modem module architecture.