il2p-rs

Current compatible IL2P version: v0.6

A simple, dependency-free Rust implementation of IL2P for packet radio. Layer 2 only.

• Type 0 transparent and typed Type 1 frames
• Scrambling
• GF(256) Reed–Solomon encoding and correction
• 16-symbol payload parity
• Optional CRC-16/X-25 with Hamming (7,4)
• MSB streaming receive and one-bit sync tolerance

Please see the IL2P specification for technical information.

Framing

use il2p::{Call, Control, Crc, Frame, Pid, UKind, decode, encode};

let frame = Frame::Translated {
    dst: Call::new("CQ", 0)?,
    src: Call::new("KK4HEJ", 15)?,
    control: Control::U {
        poll: false,
        command: false,
        kind: UKind::Ui(Pid::NONE),
    },
    data: Vec::new(),
};

let radio = encode(&frame, Crc::Hamming)?;
let recovered = decode(&radio, Crc::Hamming)?;
assert_eq!(recovered.frame, frame);
# Ok::<(), il2p::Error>(())

encode includes the three byte sync with no preamble. encode_burst tacks on any requested number of 0x55 alternating-bit bytes. Receiver accepts individual demodulated bits if byte alignment isn't known.

Frame::Transparent carries an opaque encapsulated frame (Type 0). Type 1 supports the modulo 8 control forms defined by the IL2P header.

Physical-layer implementations can feed into Receiver one bit at a time. Modulation, sample processing, synchronization, and any other Layer 1 things are outside the scope of this crate.

Verification

A handful of tests are included for checking compatibility with the spec:

• checks the lib's packets against the draft v0.6 example packets
• Type 0 and Type 1 round trips
• validation of typed callsigns, protocol IDs, and controls
• correction of one header symbol and eight payload symbols
• rejection through the trailing CRC when a bad RS correction is possible
• one bit tolerant sync acquisition at arbitrary bit alignment
• Hamming bit correction and the standard CRC check value

Run it with:

cargo test