{
  "abstract": "We present the design and performance characterization of the digital backend and precision-timing system for the Balloon-borne Very Long Baseline Interferometry Experiment (BVEX), a pathfinder for high-frequency stratospheric VLBI at 22 GHz. The backend uses one of the four 14-bit analog-to-digital converter inputs on an AMD-Xilinx RFSoC 4x2. Although the converters support sampling rates up to 5 GSPS, the flight configuration digitizes the 2-4 GHz intermediate frequency at 4.096 GSPS. CASPER firmware provides both a high-resolution spectrometer for pointing and receiver verification, and a VLBI acquisition chain with two-bit requantization that records at a rate of about 8.2 Gbps. The timestamped data packets are sent over 100 Gigabit Ethernet (GbE) to a 16 TB NVMe array in a storage computer that draws approximately 70-80 W. The timing chain uses a Rakon oven-controlled crystal oscillator as a timing reference while a time-interval counter measures its drift relative to a GPS reference with approximately 60 ps resolution. This is the first deployment of an RFSoC-based VLBI backend and precision-timing system on a stratospheric balloon. Ground tests validated the backend, spectrometer, and timing chain. The August 2025 CSA STRATOS flight ended before reaching the target float altitude because of a balloon failure, and as a result no science observations were obtained. For the planned 2027 reflight, we are developing a conduction-cooled data storage computer with 24 TB of NVMe capacity and a direct data path from the 100 GbE interface to the NVMe array.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Proc. SPIE 14153, Radio Telescopes, Technologies, and Methods, 141530Z (2026)",
  "arxiv": "2609.11605",
  "author_total": 16,
  "authors": [
    {
      "name": "Mayukh Bagchi"
    },
    {
      "name": "Felix M. Thiel"
    },
    {
      "name": "Laura M. Fissel"
    },
    {
      "name": "Maggie Oxford"
    },
    {
      "name": "Lindy Blackburn"
    },
    {
      "name": "Rafael Costa"
    },
    {
      "name": "Vincent L. Fish"
    },
    {
      "name": "Daryl Haggard"
    },
    {
      "name": "Michael D. Johnson"
    },
    {
      "name": "Dominic W. Pesce"
    },
    {
      "name": "Ganesh Rajagopalan"
    },
    {
      "name": "Javier L. Romualdez"
    },
    {
      "name": "Aarchi Shah"
    },
    {
      "name": "Adrian K. Sinclair"
    },
    {
      "name": "Stephanie St-Jean"
    },
    {
      "name": "Terry Yang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/b6ctrep1ex1ad.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.11605",
  "fulltext_url": null,
  "id": "b6ctrep1ex1ad",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.11605",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.IM"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.11605",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-10",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/b6ctrep1ex1ad.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:26Z",
      "native_id": "2609.11605",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.11605"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    }
  ],
  "title": "An RFSoC-based Backend and Timing System for the Balloon-borne Very Long Baseline Interferometry Experiment",
  "title_text": "An RFSoC-based Backend and Timing System for the Balloon-borne Very Long Baseline Interferometry Experiment",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:26Z",
  "url": "https://research.draconitic.com/paper/b6ctrep1ex1ad",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1117/12.3101053",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}