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Abstract:
This Open Research Institute (ORI) meeting recording from April 22, 2025, covers updates on several collaborative projects, primarily focusing on the Deep Space Exploration Society (DSES) 18-meter dish activities and the Earth-Venus-Earth (EVE) communication project. Rick from DSES discusses ongoing work on a next-generation antenna feed proposal, considerations for receiving Voyager spacecraft signals (requiring an 8 GHz downconverter), and planning for the 2026 EVE opportunity at 2.4 GHz with a target power of 1500W CW. Challenges include achieving this power level and ensuring signal cleanliness, though the remote site offers advantages. Significant progress is being made on the EVE link budget, incorporating advanced delay-Doppler signal processing techniques and refined Doppler spread models, aiming for actual data transmission beyond simple signal detection. The team is also analyzing European VRT software tools for potential integration and comparison during upcoming pulsar observations. Technical discussions include alternatives for EVE power generation (solid-state vs. magnetron), modifying Pluto SDRs for better frequency stability (external locking preferred over internal mods) and extending their frequency range, sourcing 8 GHz components, and the potential use of near-Earth asteroids for signal bounce tests. Collaboration with international partners, including European and potentially Australian dish sites, remains a key aspect.
ORI Meeting Summary: DSES Updates, EVE Planning, Pluto Mods & Open Discussion
0:12 DSES Updates (Rick): Discussion on preparing a PDF of the EVE link budget article for DSES.
1:01 DSES Antenna Feed Proposal: Rick is working on a Visio diagram for a next-gen antenna feed for the DSES 18m dish, integrating science and ham radio modules with an SDR up to 6 GHz and fiber optic output.
3:08 Voyager Link Budget & Reception: Rick notes a link budget for Voyager 1 in the proposal needs review, contrasting with strong European reception results. DSES is considering receiving Voyager (8 GHz), which requires a synchronized front-end downconverter.
5:45 Moon Bounce Idea: Rick suggests using the 18m dish for opulent voice moon bounce (EME) transmissions due to the high effective radiated power.
6:22 Earth-Venus-Earth (EVE) 2026 Planning: Definite plans to target the October 2026 EVE opportunity, likely at 2.4 GHz.
6:43 EVE Power Challenge: Achieving the target 1500W CW (100% duty cycle for 4+ minutes) at 2.4 GHz is a major challenge. Combining multiple 200W amplifiers is one suggestion, though designing a single high-power amplifier is preferred.
7:44 Site Interference Advantage: The DSES site's remote location (Haswell, CO, pop. 71) minimizes potential Wi-Fi interference issues from high-power 2.4 GHz transmissions.
9:34 EVE Signal & Licensing: Need for clean signals and potentially experimental licenses/variances, with ample time to address these.
10:35 EVE Goal: Communication: The aim is to move beyond radar-like carrier wave detection to actual communication, requiring more link margin (hence the 1500W goal). 2.4 GHz is near-ideal based on Venus reflectivity.
11:35 EVE Link Budget & Signal Design: Ongoing updates to the EVE link budget article, incorporating work by Pete (delay-Doppler channel protocol) and Dr. Daniel Estévez (analysis of Dwingeloo data, Doppler spread). The goal is to publish signal specifications and IQ files for participants.
13:49 Doppler Spread Insights: Recent work suggests Venus Doppler spread may be less severe than initially modeled, improving communication prospects.
17:30 Analyzing European Methods (VRT): Rick is investigating the VITA 49 Radio Transport (VRT) software toolchain used by European collaborators (Dwingeloo) for their EVE reception.
20:40 VRT Implementation Plan: Planning to set up virtual machines with the VRT tools (compiling from source) to compare with DSES's current pulsar data acquisition methods using shared RF feeds during summer observations. This will inform the EVE 2026 architecture.
24:18 EME Practice for EVE: Proposing low-power (milliwatt) EME tests at 1296 MHz using EVE hardware (with reduced power) to practice system integration and processing, acknowledging differences like Doppler spread.
26:29 EVE Power Source - Magnetrons? (Adrian/Rick): Adrian asks about using frequency-stabilized magnetrons. Rick notes legal power limits (Europeans exceeded ham limits) and the difficulty of complex modulation make solid-state preferable for the goal of communication.
30:40 Open Participation & Site Visits: Encouragement to join DSES (dses.science) and visit the site.
32:44 Lab Move Anecdotes: Shared experiences of moving lab equipment due to hurricanes and fires.
39:10 Asteroid Bounce Suggestion (Adrian/Rick): Using near-Earth asteroids as bounce targets is feasible regarding tracking; the main challenge is obtaining accurate ephemerides (Keplerians).
40:42 EME Ease & QRP Challenge: With the 18m dish, EME is relatively easy. A humorous suggestion for an ultra-low power (QRPp) EME challenge (e.g., microwatts).
41:48 Collaborations & Big Dishes: Mention of EME anecdotes from Arecibo, potential with Stanford/Haystack dishes, and ongoing/potential collaborations with European (100m dish) and Australian (Parks, Tasmania) sites for 2026.
44:02 Rick's Global Reach: Rick supplies GPS timing products to radio telescopes worldwide and attends related workshops (e.g., Haystack).
46:35 Pluto SDR Stability (Adrian/Rick): Discussion on improving Pluto SDR frequency stability. External 10 MHz locking (requires Rev C/D board) is ORI's approach. Direct oscillator replacement is possible but finding suitable drop-in TCXOs is hard; adaptation is likely needed.
51:05 Pluto SDR Frequency Extension: The software mod to extend Pluto to 6 GHz generally works, though performance at the very top end isn't guaranteed as the chips are binned. ORI has enabled it without issues in their usage range.
52:34 8 GHz Downconverter Sourcing: Finding an 8 GHz downconverter for Voyager/spacecraft reception is a challenge. Rick needs to ask European teams. Potential sources include surplus (SBMS), commercial (DB6NT), but it's not a common ham band. Adrian has acquired an 8 GHz GPS-lockable oscillator.
58:00 Pluto Plus & SDR Alternatives (Paul/Rick): Pluto Plus is suggested as an off-the-shelf option with better stability. HamGeek is a potential source. Rick mentions the HamGeek E310 SDR ($300) as another option with good specs (AD9361, Zynq 7020).
1:02:38 Logistics: Information on how to join the ORI Slack channel via the website's getting started page.