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Version: 2.0 (Legacy)

The OpenHD Ecosystem

Understanding the OpenHD system architecture and component relationships.

System Overview​

OpenHD consists of multiple interconnected components:

  • Air Unit: Onboard aircraft systems
  • Ground Unit: Ground station hardware
  • Ground Software: Control and display applications
  • Communication Protocol: Data exchange standards

Core Components​

OpenHD Core​

  • Video Pipeline: H.264/H.265 encoding and streaming
  • Telemetry System: MAVLink integration and forwarding
  • RF Management: Radio frequency control and optimization
  • Configuration System: Parameter management and storage

WFB-ng (WiFi Broadcast Next Generation)​

  • Packet Injection: Raw packet transmission
  • FEC (Forward Error Correction): Error recovery mechanisms
  • Diversity Reception: Multiple antenna support
  • Link Adaptation: Dynamic parameter adjustment

Architecture Layers​

Hardware Layer​

  • Single Board Computers: Raspberry Pi, Radxa, etc.
  • Radio Hardware: WiFi cards and antennas
  • Camera Interfaces: CSI, USB, IP cameras
  • Sensors: GPS, IMU, environmental sensors

System Layer​

  • Linux Distribution: Custom OpenHD Linux images
  • Kernel Modifications: RF drivers and optimizations
  • System Services: Background processes and daemons
  • Hardware Abstraction: Device-specific adaptations

Application Layer​

  • OpenHD Service: Main system control service
  • Camera Service: Video capture and encoding
  • Telemetry Service: MAVLink processing
  • Web Interface: Configuration web UI

User Interface Layer​

  • QOpenHD: Primary ground station software
  • Mobile Apps: Android and iOS applications
  • Web Interface: Browser-based configuration
  • OSD System: On-screen display overlay

Data Flow​

Video Pipeline​

Camera → Encoder → Packetizer → RF Transmitter
                                      ↓
RF Receiver → Depacketizer → Decoder → Display

Telemetry Flow​

Flight Controller → OpenHD Air → RF Link → OpenHD Ground → Ground Software

Control Flow​

Ground Software → OpenHD Ground → RF Link → OpenHD Air → Flight Controller

Communication Protocols​

Internal Protocols​

  • OpenHD Protocol: Internal system communication
  • MAVLink: Flight controller integration
  • REST API: Web interface communication
  • UDP Streams: Video and telemetry distribution

RF Protocols​

  • WFB-ng: Video and telemetry transmission
  • WiFi 802.11: Standard WiFi for configuration
  • Custom Frames: Optimized data structures
  • Frequency Management: Channel selection and hopping

Development Environment​

Build System​

  • CMake: Cross-platform build system
  • Cross-compilation: ARM target compilation
  • Package Management: Debian package creation
  • Continuous Integration: Automated testing and builds

Dependencies​

  • GStreamer: Video processing pipeline
  • FFmpeg: Video encoding and decoding
  • OpenCV: Computer vision operations
  • Qt: User interface framework

Development Tools​

  • Git: Version control system
  • GitHub: Repository hosting and collaboration
  • Docker: Containerized build environments
  • QEMU: ARM emulation for testing

Component Interaction​

Service Communication​

  • D-Bus: Inter-process communication
  • Shared Memory: High-performance data sharing
  • Unix Sockets: Local communication channels
  • Network Sockets: Remote communication

Configuration Management​

  • JSON Configuration: Human-readable settings
  • Parameter Validation: Input validation and bounds checking
  • Default Values: Fallback configuration values
  • Runtime Updates: Dynamic parameter changes

Extension Points​

Plugin Architecture​

  • Video Plugins: Custom video processing
  • Telemetry Plugins: Custom telemetry handling
  • OSD Plugins: Custom display elements
  • Protocol Plugins: Additional communication protocols

API Interfaces​

  • REST API: HTTP-based configuration interface
  • WebSocket API: Real-time data streaming
  • UDP API: Low-latency data access
  • Callback API: Event-driven programming

Quality Assurance​

Testing Framework​

  • Unit Tests: Component-level testing
  • Integration Tests: System-level testing
  • Hardware Tests: Real hardware validation
  • Performance Tests: Latency and throughput measurement

Code Quality​

  • Static Analysis: Code quality checking
  • Code Reviews: Peer review process
  • Documentation: Comprehensive code documentation
  • Coding Standards: Consistent coding practices

Deployment​

Image Building​

  • Custom Linux Images: Tailored system images
  • Package Installation: Automated package deployment
  • Configuration Templates: Default system configurations
  • Hardware Variants: Device-specific optimizations

Update Mechanism​

  • OTA Updates: Over-the-air system updates
  • Package Updates: Individual component updates
  • Configuration Migration: Settings preservation
  • Rollback Capability: Revert to previous versions

Performance Considerations​

Latency Optimization​

  • Pipeline Optimization: Minimize processing delays
  • Kernel Bypassing: Direct hardware access
  • Priority Scheduling: Real-time process scheduling
  • Buffer Management: Minimize buffering delays

Resource Management​

  • CPU Allocation: Process priority management
  • Memory Management: Efficient memory usage
  • Power Management: Battery life optimization
  • Thermal Management: Heat dissipation strategies

Future Development​

Planned Features​

  • AI Integration: Computer vision and autonomous features
  • Cloud Integration: Remote monitoring and control
  • Mesh Networking: Multi-node communication
  • Protocol Evolution: Enhanced communication protocols

Technology Roadmap​

  • Hardware Support: New platform support
  • Protocol Enhancements: Improved communication
  • User Interface: Enhanced user experience
  • Performance: Continued optimization
Developer Resources

Additional developer documentation, APIs, and tools are available in the OpenHD GitHub repositories.

System Complexity

The OpenHD ecosystem is complex. Start with simple modifications and gradually work on more complex features.

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