Satellite Tracking

Compute where to point a ground-station antenna at a satellite — as a web console, from the command line, or as a Python library. It also carries a DIFI / VITA 49.2 digitised IF stream, for the signal side of the same ground station.

Quick start

python -m venv .venv && source .venv/bin/activate
pip install -r config/requirements.txt

python src/fetch_tle.py     # grab a current ISS element set -> data/gp_25544.json
python src/app.py           # open http://127.0.0.1:8000/

Windows

python -m venv .venv
.venv\Scripts\activate
pip install -r config/requirements.txt

python src\fetch_tle.py
python src\app.py

All commands are run from the satellite_tracking/ project root.

Documentation

Guide	What is in it
docs/console.md	The web console: parameters, sky plot and timeline, pass selection, live map, sample flags, the HTTP API, and automatic element-set renewal
docs/cli.md	acu.py, acu_rt.py and fetch_tle.py on the command line, scheduling TLE refreshes with cron or Task Scheduler, and using acu.py as a library
docs/difi.md	difi_tx.py / difi_rx.py — DIFI 1.x (VITA 49.2) transmitter and validating receiver

The console has no authentication and lets any visitor read files from data/ and trigger CelesTrak fetches, so only use --host 0.0.0.0 on a trusted network.

What is here

File	What it is
src/index.html	ACU console web UI — set the antenna parameters in a form, get az/el back as a sky plot, timeline, table, pass list, and a live map + readout
src/world.js	Simplified world coastlines drawn by the live map (Natural Earth 1:110m, public domain)
src/app.py	Flask server behind the console: serves the page and exposes the az/el engine over HTTP
src/acu.py	Az/el engine, and a command-line calculator for a single instant or a 24-hour sweep, with optional JSON export
src/acu_rt.py	Real-time az/el tracker; prints the live position until stopped
src/fetch_tle.py	Downloads the latest GP (OMM) element set from CelesTrak into data/
src/tle_renew.py	Keeps those element sets fresh on a schedule, twice a day by default, while the console runs
src/difi_tx.py	DIFI / VITA 49.2 transmitter — streams a synthetic digitised IF flow over UDP
src/difi_rx.py	DIFI / VITA 49.2 receiver — decodes that flow and checks it against the standard

Project layout

satellite_tracking/
├── src/                    # index.html, world.js, app.py, acu.py, acu_rt.py, fetch_tle.py
│                           # tle_renew.py, difi_tx.py, difi_rx.py
├── docs/                   # console.md, cli.md, difi.md
├── data/                   # element sets from fetch_tle.py, JSON exports from acu.py --output
└── config/
    ├── requirements.txt    # Python dependencies
    └── tle_renew.json      # automatic renewal schedule (created on first run)

Requirements

• Python 3.9+

• Dependencies in config/requirements.txt:

  Package	Used by	Purpose
  skyfield==1.54	src/acu.py, src/acu_rt.py	Orbital mechanics / az-el computation
  sgp4==2.27	src/acu.py	TLE and GP (OMM) propagation, parses JSON/XML/CSV element sets
  flask==3.1.3	src/app.py	Web console server (serves the UI and the API)
  flask-cors==6.0.5	src/app.py	CORS support, for calling the API from a page served elsewhere

Network access is only needed to pull element sets: fetch_tle.py, the console's Fetch and Renew now buttons, the norad satellite mode, and automatic renewal. Everything else — propagation, the plots, the live map — runs offline. tle_renew.py and the two DIFI applications need nothing beyond the standard library.