GNSS Logger & Analysis Toolkit

Automated GNSS testing, logging, and performance analysis suite

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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.

Brand assets

The project name and the logo files in this repository are not part of the licensed work. The licence above grants no permission to use them, except as needed to describe the origin of the work.