# Signal Synchronization

> Perform carrier frequency offset (CFO) recovery, phase lock, and symbol clock timing synchronization using native GNU Radio blocks (digital.costas_loop_cc, digital.symbol_sync_cc).

- Skill: `nitrojacob/signal-synchronization` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add nitrojacob/signal-synchronization`
- Raw SKILL.md: https://api.skillmd.com/api/skills/nitrojacob/signal-synchronization/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: nitrojacob (https://skillmd.com/u/nitrojacob)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/nitrojacob/signal-synchronization

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# Signal Synchronization Skill ⏱️

Use this skill to align carrier frequency, lock carrier phase, and sync symbol timing on digital modulated signals (BPSK, QPSK, 8PSK, QAM).

## Instructions

1. **Execute Synchronization Tool**:
   ```bash
   PYTHONPATH=/usr/lib/python3/dist-packages:./ .agents/skills/signal-synchronization/scripts/synchronize_signal.py --input <cleaned_sigmf_file> --mod <QPSK|BPSK|16QAM> --output <synced_sigmf_file>
   ```

2. **Native GNU Radio Blocks Employed**:
   - Power-of-N FFT Peak Estimator: Coarse CFO recovery.
   - `digital.costas_loop_cc`: Fine CFO tracking & carrier phase locking.
   - `digital.symbol_sync_cc`: Gardner Timing Error Detector (TED) & interpolator for clock drift recovery.

3. **Verify EVM**:
   Check Error Vector Magnitude (EVM %) metric in report. Low EVM (< 15%) indicates tight constellation alignment ready for demodulation.