Sub-GHz Analyzer

Analyze and work with Sub-GHz protocols in Momentum Firmware, including protocol development and signal analysis.

Context

• Momentum Firmware supports extended Sub-GHz frequencies (281-962 MHz)
• Uses CC1101 transceiver for Sub-GHz communication
• Protocols are defined in lib/subghz/protocols/
• Signal analysis tools available in external apps

Protocol Structure

Sub-GHz protocols in Momentum follow this pattern:

typedef struct {
    SubGhzProtocolDecoderBase base;
    SubGhzBlockDecoder decoder;
    SubGhzBlockGeneric generic;
    // Protocol-specific fields
} SubGhzProtocolDecoderProtocolName;

Key Components

1. Protocol Registry:

   • Located in lib/subghz/subghz_protocol_registry.h
   • Registers all available protocols
   • Handles protocol selection and initialization

2. Signal Processing:

   • Raw signal capture and analysis
   • Manchester/PWM decoding
   • Bit extraction and validation

3. File Formats:

   • .sub files store captured signals
   • Flipper Format for structured data
   • Raw signal data for analysis

Analysis Process

1. Capture Signal:

   • Use Sub-GHz app to record unknown signals
   • Save as raw format for analysis
   • Note frequency, modulation, and timing

2. Analyze Pattern:

   • Look for repeating patterns
   • Identify sync/preamble sequences
   • Determine bit encoding (Manchester, PWM, etc.)

3. Extract Data:

   • Parse bit stream for meaningful data
   • Identify fixed vs. variable portions
   • Look for checksums or validation

4. Create Protocol:

   • Implement decoder following existing patterns
   • Add encoder if transmission needed
   • Register in protocol registry

Development Tools

• applications/external/sub_analyzer/ - Signal analysis app
• applications/external/protoview/ - Protocol viewer
• CLI tools for raw signal processing
• Spectrum analyzer for frequency analysis

Testing

• Test with known good signals first
• Verify decoding accuracy
• Test edge cases and noise handling
• Validate against original equipment