CCSDS Parser & Simulator

A compact CCSDS packet parser and UDP simulator written in C.

This repository contains a simple telemetry receiver (ccsds_parser) that listens on UDP port 7000, parses CCSDS primary headers, detects sequence gaps, logs packet metadata to telemetry.csv, and dispatches packets to subsystem handlers. A companion sender (ccsds_simulator) generates valid CCSDS telemetry packets and sends them to the parser for testing.

Features

• CCSDS primary header parsing with proper big-endian field extraction
• Telemetry packet validation (version checks, packet length)
• Sequence gap detection per APID with wrap-around support
• Dispatch table for subsystem-specific packet handling
• CSV logging of packet metadata and anomalies
• UDP-based simulator for generating telemetry traffic

Repository structure

• Makefile - build targets for ccsds_parser and ccsds_simulator
• include/ccsds.h - shared CCSDS type definitions, constants, and function declarations
• src/main.c - UDP receiver and main loop for the parser application
• src/parser.c - CCSDS packet parsing and dispatch initialization
• src/anomaly.c - sequence tracking and anomaly detection logic
• src/logger.c - CSV logging and terminal output formatting
• src/simulator.c - UDP packet generator for testing the parser
• telemetry.csv - generated log file output from parser runs

Build

From the repository root, run:

make

This builds two executables:

• ccsds_parser
• ccsds_simulator

Run

1. Start the parser in one terminal:

./ccsds_parser

2. Start the simulator in another terminal:

./ccsds_simulator

The parser listens on UDP port 7000 and prints packet status to the console. The simulator sends telemetry packets to 127.0.0.1:7000 at a fixed rate and injects deliberate sequence gaps for anomaly detection.

Logging

The parser writes packet logs to telemetry.csv with the following columns:

• timestamp_ms
• apid
• seq_count
• payload_len
• anomaly

If the log file cannot be opened, the parser still runs and prints warnings to stderr.

CCSDS behavior

The parser supports:

• 6-byte CCSDS primary header
• version field validation (must be 0)
• APID values up to 0x7FF
• packet sequence flags and counters
• payload extraction after the primary header

Subsystems

The following APIDs are handled explicitly in the parser:

• 0x001 — attitude control
• 0x002 — power management
• 0x003 — thermal

Unknown APIDs are handled by a default fallback routine.

Notes

• ccsds_parser is designed as a teaching/demo implementation and is not a full flight software stack.
• The simulator uses usleep() to control packet rate and intentionally skips a sequence number every 15 packets for one subsystem.

Clean

To remove executables and generated log output:

make clean