GNSS Logger & Analysis Toolkit

A comprehensive Python suite for automated GNSS testing, logging, and performance analysis. Designed for Telit-based modules with standard NMEA output, this toolkit provides:

• gnss_logger.py
  Resets & powers-on the GNSS engine, enables NMEA output, and captures raw NMEA sentences to file.
  Key functions inside:

  • send_reset(mode) — sends cold/warm/hot reset via AT command
  • enable_nmea() — configures which NMEA sentences to output
  • capture_nmea(duration, output_file) — logs incoming NMEA lines for the specified time

• gnss_nmea_analysis.py
  Parses a saved NMEA log, computes TTFF, CEP₅₀/₉₅, RMS error, and generates standard plots.
  Key functions inside:

  • parse_nmea(nmea_file) — extracts time, fix quality, lat/lon, HDOP, satellite count
  • haversine(lat1, lon1, lat2, lon2) — computes great-circle distance
  • main() (CLI entry point) — handles arguments, computes metrics, writes CSV + PNGs

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📋 Table of Contents

• GNSS Logger & Analysis Toolkit
  • 📋 Table of Contents
  • 📋 Prerequisites
  • 🔧 Installation
  • 🛠 Usage
    • 1. GNSS Logger (gnss_logger.py)
      • Console Output
      • Output
    • 2. NMEA Analysis (gnss_nmea_analysis.py)
      • Generated Files (same folder as --nmea-file)
  • 📊 Example Outputs
    • 3. Analysis GUI (gnss_analysis_gui)
    • Outputs (saved alongside your NMEA log file)
  • 📈 Metrics & Plots
  • ⚙️ Customization
  • ⚖️ License

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📋 Prerequisites

• Python 3.7+
• pip (Python package manager)
• Tkinter (for GUI):
  • Linux:

    sudo apt-get install python3-tk

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🔧 Installation

1. Clone the repository

   git clone https://github.com/RFingAdam/gnss-toolkit
   cd gnss-toolkit

``

2. Install dependencies

   pip install pyserial pandas numpy matplotlib

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🛠 Usage

1. GNSS Logger (gnss_logger.py)

Capture raw NMEA sentences from a Telit GNSS module:

python gnss_logger.py <COM_PORT> [--mode MODE] [--duration SECONDS] [--output FILE]

Option	Description
<COM_PORT>	Serial port, e.g. COM4 (Windows) or /dev/ttyUSB0 (Linux/macOS)
--mode	GNSS start mode: cold (default), warm, or hot
--duration	Logging duration in seconds (default: 900)
--output	Output filename for the NMEA log (default: nmea_capture.txt)

Console Output

• AT command responses & OK messages
• # START HHMMSS header marking session timestamp
• 🎯 First-fix notification
• Live NMEA sentences streamed to console

Output

• Raw NMEA log file containing only NMEA sentences (plus the header)

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2. NMEA Analysis (gnss_nmea_analysis.py)

Parse an NMEA log, compute performance metrics, and generate plots:

python gnss_nmea_analysis.py \
  --nmea-file path/to/nmea_capture.txt \
  --start-time HHMMSS \
  --ref-lat <latitude> \
  --ref-lon <longitude>

Parameter	Description
--nmea-file	Path to the NMEA log (produced by gnss_logger.py)
--start-time	GNSS start time in UTC (format HHMMSS)
--ref-lat, --ref-lon	Reference coordinates (decimal degrees)

Generated Files (same folder as --nmea-file)

Filename	Description
<basename>_summary.csv	CSV summary of TTFF, CEP₅₀/₉₅, RMS, and fix count
error_histogram.png	Error distribution histogram with CEP₅₀/₉₅ markers
scatter_with_cep.png	ENU scatter plot of fixes with CEP₅₀/₉₅ circles
error_vs_hdop.png	Scatter of HDOP vs. horizontal error
sats_vs_time.png	Plot of satellite count vs. UTC time
summary_notes.txt	Plaintext report containing all metrics and samples

📊 Example Outputs

Below are sample results generated by gnss_nmea_analysis.py / the GUI:

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3. Analysis GUI (gnss_analysis_gui)

Tkinter GUI wrapping the same analysis logic with summary export:

1. Browse… to select your NMEA log file
2. Enter Start Time (HHMMSS) (e.g. 192841)
3. Enter Reference Latitude & Longitude (decimal degrees)
4. Click Run Analysis

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Outputs (saved alongside your NMEA log file)

Filename	Description
summary_notes.txt	Plaintext report of TTFF, CEP₅₀/₉₅, RMS, sample fixes
error_histogram.png	Histogram of horizontal errors with CEP markers
scatter_with_cep.png	ENU scatter plot with CEP₅₀/₉₅ circles
error_vs_hdop.png	Scatter of HDOP vs. horizontal error
sats_vs_time.png	Plot of satellite count vs. UTC time

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📈 Metrics & Plots

Metric	Description
TTFF (s)	Time‐to‐first‐fix after GNSS power‐on
CEP₅₀ / CEP₉₅ (m)	Radii containing 50 % / 95 % of horizontal fixes
RMS Error (m)	Root‐mean‐square of horizontal errors
Error Histogram	Distribution of horizontal errors with CEP₅₀/₉₅ lines
ENU Scatter	East/North offsets (m) with CEP₅₀/₉₅ rings
HDOP vs Error	Relationship between HDOP values and observed error
Satellites vs Time	Number of tracked satellites throughout the session

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⚙️ Customization

• Tweak histogram bins or styling
• Add support for additional NMEA sentences (e.g. GSA, RMC)
• Modify CLI flags (logging duration, mode, output paths)
• Extend analysis with new metrics (e.g. HDOP time-series)

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⚖️ License

Licensed under the GNU GPL v3.0. See LICENSE for details.