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v1.15.1 - GNSS Timing Optimization (2025-12-12)

What Changed?

This patch release optimizes GNSS data capture timing by moving it immediately after RTC timestamp capture. The change improves timing accuracy for multi-detector synchronization and prioritizes satellite acquisition timing without affecting detection logic or backward compatibility.

What's New

Sensor Read Order Optimization

What it does: Optimizes the order in which sensor data is captured during detection processing to prioritize timing-critical measurements. The new order captures absolute timestamps and position data immediately after detection, before slower sensor measurements.

New sensor read order:

1. RTC timestamp (detected_at)       ← Detection moment
2. GNSS position data                ← Satellite acquisition priority
3. Timestamp fields (uptime_ms)      ← Elapsed time tracking
4. ADC millivolts (adc_raw, adc_mv)  ← Voltage measurement
5. BME280 environmental              ← Slower I2C sensor

Why this matters:

  • GNSS receivers need time to acquire satellite signals
  • Early capture ensures position reflects detection moment
  • Improves timing accuracy for multi-detector cosmic ray event correlation
  • Maintains all existing data without format changes

Installation

Quick Start

# Get the release
git checkout vX.Y.Z

# Build
task build

# Upload
task upload

# Check it works
task monitor

What's Different from the Last Version?

✅ Added

  • Optimization of sensor read order for improved timing accuracy
  • Documentation of new sensor read order in CLAUDE.md

🔧 Changed

  • Sensor data capture order optimized to prioritize timing-critical measurements
  • RTC timestamp now captured immediately after detection (before GNSS, not after all sensors)
  • GNSS position data captured before slower sensor reads (improves satellite acquisition timing)
  • Both Legacy and Unified protocol paths use identical sensor read order

🐛 Fixed

  • Improved timing accuracy for multi-detector cosmic ray event correlation

Is It Safe to Upgrade?

Backward Compatible: Yes

  • Data format unchanged (all existing fields remain, no new fields)
  • Output format identical (SSV/TSV/CSV/JSONL formats unchanged)
  • JSON field names unchanged (v1.15.0 breaking change already applied)
  • Timing improvement is transparent to data consumers
  • No API changes or breaking changes

Tests Passed

  • ✅ Default build (no optional sensors): SUCCESS
  • ✅ RTC enabled build: PLATFORMIO_BUILD_FLAGS="-DENABLE_RTC=1" pio run -e esp32dev-release SUCCESS
  • ✅ GNSS enabled build: PLATFORMIO_BUILD_FLAGS="-DENABLE_GNSS=1" pio run -e esp32dev-release SUCCESS
  • ✅ Combined RTC + GNSS build: PLATFORMIO_BUILD_FLAGS="-DENABLE_RTC=1 -DENABLE_GNSS=1" pio run -e esp32dev-release SUCCESS
  • ✅ Unified protocol with GNSS: PLATFORMIO_BUILD_FLAGS="-DENABLE_DEVICE_RESPONSE=1 -DENABLE_GNSS=1" pio run -e esp32dev-next SUCCESS
  • ✅ Pre-commit hooks pass (commitizen, trailing whitespace, file endings)

Release Details

  • Date: 2025-12-12
  • Version: v1.15.1
  • Files Changed: 3 (src/detection_processor.cpp, src/main.cpp, include/detection_processor.h)
  • Commit: 85cf559 (refactor(rtc): move gnss data capture earlier for satellite acquisition timing)

Next Steps

Roadmap considerations:

  • Monitor timing accuracy improvements in multi-detector deployments
  • Plan Phase 2 optimization: Consider configurable sensor read order via runtime flags
  • Evaluate performance impact of earlier GNSS reads (satellite acquisition times)
  • Plan Phase 3: Add timing instrumentation to measure actual sensor read latencies