RADIANT — Radio Amateur Delay-tolerant Interplanetary Networking Testbed

From amateur packet radio to CubeSat relay to cislunar networking.

RADIANT brings Delay-Tolerant Networking (DTN) to amateur radio, enabling store-and-forward messaging across disrupted links from terrestrial ground stations to Low Earth Orbit (LEO) and ultimately to cislunar space. Current status: two-node terrestrial DTN operational (Raspberry Pi, Mobilinkd TNC4, Yaesu FT-817, 9600 baud G3RUH GFSK over VHF/UHF). All subsequent phases are in design or planning.

The project implements Bundle Protocol version 7 (BPv7) over amateur radio links using LTP wrapped directly in KISS framing. The architecture is DTN-implementation-agnostic — a common abstraction layer supports multiple DTN engines (NASA Glenn's HDTN, JPL's ION-DTN, µD3TN, and Hardy) through a unified interface, allowing operators to select the engine best suited to their platform and mission phase. Station identification is achieved through callsign-embedded DTN Endpoint Identifiers (e.g. dtn://g4dpz/spacecraft) carried in every bundle's metadata, ensuring regulatory compliance while using numeric ipn:// addresses for efficient routing.

RADIANT — Radio Amateur Delay-tolerant Interplanetary Networking Testbed

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Current Status

RADIANT is an early-stage project. Here is what exists today and what is planned.

Operational Now (Phase 1)
  • Two-node terrestrial DTN over VHF/UHF
  • Hardware: Raspberry Pi + Mobilinkd TNC4 + Yaesu FT-817
  • 9600 baud G3RUH GFSK — standard amateur packet modulation
  • BPv7 bundles over LTP wrapped directly in KISS framing
  • Ping and store-and-forward file delivery validated
  • Simulated propagation delay (cislunar/interplanetary timing) in lab
  • Callsign-embedded DTN Endpoint Identifiers for regulatory compliance
In Design / Planned
  • Phase 1.5: QO-100 GEO satellite DTN demonstration
  • Phase 2: CubeSat engineering model (STM32U585 + SDR)
  • Phase 3: LEO CubeSat flight with ground-to-space DTN
  • Phase 4: Cislunar S-band/X-band with FEC (LDPC)
  • Adaptive modulation (4FSK, QPSK) replacing baseline GFSK
  • Forward error correction (convolutional, Reed-Solomon, LDPC)
  • Multi-engine DTN abstraction layer
  • Source code repository (not yet public)

How Store-and-Forward Works

DTN bundles are uploaded during one pass window, stored persistently onboard, and forwarded to the destination when the next contact opens — no data lost due to disconnection.

Sequence diagram showing DTN store-and-forward operation: Ground Station A uploads a bundle to the CubeSat during Pass 1, the bundle persists in non-volatile memory during a no-contact period, then the CubeSat forwards it to Ground Station B during Pass 2.

Network Architecture

From terrestrial ground stations through GEO relay to cislunar deep space — all connected via standard DTN protocols.

RADIANT network architecture diagram showing ground segment (mission operations, ground gateway, ground stations) connected via RF links to LEO CubeSat, QO-100 GEO relay, and cislunar node near the Moon.

What This Project Is

RADIANT is a networking-layer integration project, not a PHY-layer innovation project. The value is in making DTN work end-to-end over amateur radio links with proper regulatory compliance, contact scheduling, and store-and-forward semantics — then progressively improving the physical layer as we move toward space.

Amateur Radio as DTN Testbed

Amateur radio links are naturally disrupted, intermittent, and scheduled — exactly the environment DTN was designed for. LEO passes, QO-100 transponder slots, and terrestrial VHF links all exercise real DTN behaviours.

DTN Integration

Running the NASA/JPL interplanetary internet protocol suite (BPv7, LTP, CGR) on affordable amateur ground stations. The engineering is in the integration: LTP-over-KISS, callsign-embedded EIDs, contact plan management.

Phased Approach

Starting with proven, simple hardware (TNC4 + FT-817) and progressively moving to software-defined radio, adaptive modulation, and eventually flight hardware. Each phase validates the next.

Technical Capabilities (Operational + Planned)

✓ DTN-implementation-agnostic — supports HDTN, ION-DTN, µD3TN, and Hardy via a common abstraction layer
✓ Working 3-node cislunar simulation with true packet-level propagation delay
✓ Validated DTN store-and-forward with simulated cislunar (1.3s) and interplanetary (3–12 min) propagation delays
✓ LTP-over-KISS with callsign-embedded DTN Endpoint Identifiers (amateur radio compliance)
✓ Contact Graph Routing (CGR) computing multi-hop paths through relay nodes
✓ Multi-node contact graph with time-dependent routing across ground stations, LEO, GEO, and cislunar nodes
✓ Automated contact plan distribution: REST API for ground stations, OTA bundles for spacecraft
✓ No encryption or cryptography (amateur radio regulatory compliance)
✓ Priority-based bundle handling (critical, expedited, normal, bulk)
✓ Persistent bundle storage surviving power cycles
✓ Real-time telemetry and health monitoring via HDTN REST API

Protocol Stack

RADIANT eliminates AX.25 and wraps LTP directly in KISS framing — reducing overhead and improving throughput by ~10%.

Protocol stack comparison: RADIANT uses Application, BPv7, LTP, KISS framing, and G3RUH 9600 baud directly, while traditional packet radio adds an AX.25 layer with 15 bytes overhead per frame.

Our Collaborators

This project is developed in collaboration with leading amateur satellite organisations.

AMSAT-UK logo AMSAT-UK
AMSAT-DL logo AMSAT-DL
Goonhilly Earth Station logo Goonhilly Earth Station

Get Involved

We are actively seeking collaborators — amateur radio operators, researchers, universities, and space organisations.

Whether you can offer ground station partnerships, hardware contributions, flight opportunities, or software development expertise, we want to hear from you.

Contact Us to Collaborate

MIT License