ccsds

CCSDS Spacecraft Data Stream Decoding

The project provides tools for decoding spacecraft downlink telemetry streams conforming to the CCSDS recommended specifications (Blue Books) TM Synchronization and Channel Coding and Space Packet Protocol.

Supports:

• Framing
  • Stream synchronization
  • Pseudo-noise removal
  • Reed-Solomon FEC
• Spacepacket decoding
  • Telemetry packets, i.e., packets with type 0
  • Sequencing
  • Packet groups
• Limited support for secondary header timecodes
  • CCSDS Day Segmented timecodes
  • NASA EOS timecodes for Aqua and Terra spacecrafts
  • Provided but not directly used

Examples

The following example shows how to decode an unsynchrozied byte stream of CADUs for the Suomi-NPP spacecraft. This example code should work for any spacecraft data stream that conforms to CCSDS TM Synchronization and Channel Coding and Space Packet Protocol documents.

use std::fs::File;
use std::io::BufReader;
use ccsds::{ASM, FrameDecoderBuilder, Synchronizer, decode_framed_packets, collect_packet_groups, PacketGroup};

// 1. Synchronize stream and extract blocks (CADUs w/o ASM)
let file = BufReader::new(File::open("snpp.dat")
    .expect("failed to open data file"));
let blocks = Synchronizer::new(file, &ASM.to_vec(), 1020)
    .into_iter()
    .filter_map(Result::ok);

// 2. Decode those blocks into Frames
let frames = FrameDecoderBuilder::default()
    .reed_solomon_interleave(4)
    .build(blocks);

// 3. Extract packets from Frames
// Suomi-NPP has 0 length izone and trailer
let packets = decode_framed_packets(157, frames, 0, 0);

References:

• CCSDS
• Space Packet Protocol
• TM Synchronization and Channel Coding
• TM Synchronization and Channel Coding - Summary of Concept and Rationale

License

GNU General Public License v3.0