Two callsigns, one operator
I'm James Xue — a student, developer, and amateur-radio operator working as BD1DMB from the Beijing region (grid OM89) and KD3CSB from New Castle, Delaware (grid FM29).
A student who fell in love with the spectrum
I'm a high-school student and self-taught developer who got pulled into amateur radio the first time a handful of watts carried my voice to a stranger on the other side of a mountain. That little miracle — that radio works at all — has shaped almost everything I've built since.
By day I write code: web applications, data pipelines, and increasingly the retrieval-augmented AI systems that are quietly rewiring how software answers questions. By night I'm in the shack, chasing weak signals, decoding satellite telemetry, and logging contacts that turn a map of the world into a list of people I've actually spoken to.
The two halves aren't separate. Radio taught me to respect physics and noise floors; programming gave me the tools to bend them. Somewhere in the overlap — SDR, DSP, embedded systems, and the maths of orbits — is the work I most want to do, and the reason this station exists in the first place.
At a glance
- Operator
- James Xue
- Callsigns
- BD1DMB · KD3CSB
- Grid
- OM89
- QTH
- Beijing region, China
- Mode
- FM · SSB · CW (CWO)
- Roles
- Student · Developer · Ham
Learning, formally and at the bench
The classroom matters, but most of what I know about radio and code came from breaking things and fixing them again.
Secondary school
Currently a high-school student focused on mathematics, physics, and computer science — the foundation under every link budget and flowgraph I touch.
Self-directed RF & software
Licensed amateur and self-taught developer: antenna theory, DSP, GNU Radio, full-stack web development, and the AI systems I build to learn the rest faster.
Where radio, code, and space overlap
The recurring themes across the projects, the logbook, and the late nights.
Satellites & the ISS
Working FM and linear birds — SO-50, the RS-44 transponder, and APRS digipeating through the ISS. Doppler-corrected passes are equal parts orbital mechanics and antenna craft.
Software-Defined Radio
Living in the waterfall with an RTL-SDR and an SDRplay: decoding weather satellites, hunting weak HF signals, and writing GNU Radio flowgraphs to demodulate the modes commercial rigs ignore.
RAG & applied AI
Building retrieval-augmented systems that ground large language models in real documents — vector search, embedding pipelines, and evaluation harnesses for answers you can actually trust.
Audio & DSP
From SSB filters to room acoustics: digital signal processing is the thread connecting radio, music, and code. I build small tools for analysis, filtering, and clean monitoring.
Orbital mechanics & KSP
Kerbal Space Program turned delta-v budgets and Hohmann transfers into intuition. It is the most fun anyone can have learning why rockets are hard and rendezvous is harder.
Space science
Tracking launches, reading mission profiles, and understanding the link budgets that let a few watts reach a spacecraft. Radio is how humanity talks to everything beyond the atmosphere.
The roadmap from here
Concrete, dated-when-I-can-make-them ambitions for the station and for me.
Stand up the school amateur-radio station
Get a club callsign on the air with a working HF/VHF setup, train the first cohort of student operators, and run a satellite demo that turns a passing spacecraft into a classroom.
University study in engineering & CS
Read electrical engineering and computer science at a strong programme — formalising the RF, DSP, and systems knowledge I have been building hands-on at the bench.
Earn DXCC
Confirm 100 distinct DXCC entities from grid OM89 — a long, patient project across HF openings, satellite footprints, and careful logging and QSLing.
Operate KD3CSB from the US
Upgrade the US licence and put KD3CSB on the air from the field — bridging two callsigns, two regulatory worlds, and cross-continental contacts.
Milestones on the air and off
A running log of the moments that built the station.
- Award
Worked the ISS
First contact through the International Space Station
- Radio
Founded the school radio club
Began mentoring students toward their licences
- Project
Started the Industrial HMI RAG system
Production retrieval-augmented assistant
- Radio
Obtained US callsign KD3CSB
Passed the FCC Technician exam
- Project
Began the Caffeine app
Started building my macOS focus app
- Radio
First satellite QSO
Made a contact through SO-50
- Project
Started the AI Agent Experiments lab
Began exploring tool-using LLM agents
- Radio
First HF DX contact
Worked Japan on 20m SSB
- Radio
Licensed as BD1DMB
Earned my Chinese amateur radio licence
Awards & confirmations
Certificates, contest finishes, and the operating awards worth framing.
DXCC (in progress)
ARRL
Worked 80+ DXCC entities across HF
Jan 2026
Worked All Continents
IARU
Confirmed contacts on all six inhabited continents
Sep 2025
Satellite Communicator
AMSAT
Multiple confirmed satellite QSOs incl. the ISS
Apr 2026
CW operator milestone
Built reliable CW copy and logging practice across HF contacts
Dec 2025