Crate 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;
use ccsds::{FrameDecoderBuilder, decode_framed_packets, collect_packet_groups, PacketGroup};

let file = fs::File::open("snpp.dat")
    .expect("failed to open data file");
let frames = FrameDecoderBuilder::new(1024)
    .reed_solomon_interleave(4)
    .build(file);
// Suomi-NPP has 0 length izone and trailer
let packets = decode_framed_packets(157, Box::new(frames), 0, 0);

// The VIIRS sensor on Suomi-NPP uses packet grouping, so here we collect the packets
// into their associated groups.
let groups: Vec<PacketGroup> = collect_packet_groups(Box::new(packets))
    .filter_map(|zult| zult.ok())
    .collect();

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

Modules

• timecode
  Timecode parsing for CCSDS Space Packet data.

Structs

• DecodedFrame
• DecodedFrameIter
  Provides Frames based on configuration provided by the parent FrameDecoderBuilder.
• DefaultReedSolomon
  Implements the CCSDS documented Reed-Solomon FEC.
• Frame
• FrameDecoderBuilder
  Builds a DecodedFrameIter that will return all frames decoded from the stream read from reader.
• Framing
  Spacecraft framing configuration.
• MPDU
• Packet
  Packet represents a single CCSDS space packet and its associated data.
• PacketGroup
  Packet data representing a CCSDS packet group according to the packet sequencing value in primary header.
• PrimaryHeader
  CCSDS Primary Header
• RSConfig
  Spacecraft Reed-solomon configuration
• Synchronizer
  Synchronizer scans a byte stream for data blocks indicated by a sync marker.
• VCDUHeader

Enums

• RSState
  Disposition of the RS process

Constants

• ASM
  Default CCSDS attached sync marker.
• MAX_SEQ_NUM
  Maximum packet sequence id before rollover.
• SEQ_CONTINUATION
  Packet is a part of a packet group, but not first and not last
• SEQ_FIRST
  Packet is the first packet in a packet group
• SEQ_LAST
  Packet is the last packet in a packet group
• SEQ_UNSEGMENTED
  Packet is not part of a packet group, i.e., standalone.
• VCDU_COUNTER_MAX
• VCID_FILL
  VCID value indicating fill data

Traits

• ReedSolomon

Functions

• collect_packet_groups
  Collects the provided packets into PacketGroups.
• decode_framed_packets
  Decodes the provided frames into a packets contained within the frames’ MPDUs.
• missing_frames
  Calculate the number of missing frame sequence counts.
• missing_packets
  Calculate the number of missing sequence ids.
• read_packet_groups
  Return an Iterator that groups read packets into PacketGroups.
• read_packets
  Return an iterator providing Packet data read from a byte synchronized ungrouped packet stream.
• read_synchronized_blocks
  Creates an iterator that produces byte-aligned data blocks.
• rs_correct_message
  Correct a Reed-Solomon code block. The returned Block’s message will contain the corrected message iff the state is RSState::Corrected. Otherwise it will be None.
• rs_deinterleave
  Deinterleave an interleaved RS block (code block + check symbols).
• rs_has_errors
  Return true if the input code block contains 1 or more errors.

Type Aliases

• APID
• SCID
• VCID