TLE-tracker 0.3.0

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TLE (position) tracker

TLE service for WUST-Sat OBC.

Tests and linter

This project enforces code quality using listed tools:

black - code formatter that ensures consistent style across the project
isort - organizes import statements into sections and alphabetically
ruff - linter for code quality checks and automatic fixes

You can test quality of code using poe command:

poe format will automatically correct formatting, import order, and check if ruff returns errors.
poe format_check will run checkers and linters, but without editing the code.

TLE Tracker on Raspberry Pi

To deploy and run the TLE_tracker service on a Raspberry Pi, use the dedicated Ansible playbook:

Playbook: tle-tracker.yml

Repository: Wust-Sat/obc-system

Dependecies

Please install mosquitto or provide different MQTT server.

Features

This repository enable starting service using mqtt library to calculate position of satellite:

• time of the request
• latitide
• longitude
• altitude (in km)

To calculate posittion of a satellite client needs TLE (2 lines) and broker (mosquitto). You can always send TLE via terminal like this:

mosquitto_pub -h localhost -t cubesat/tle -m "1 25544U 98067A   20029.54791435  .00001264  00000-0  29621-4 0  9993\n2 25544  51.6434  21.3435 0007417 318.0083  42.0574 15.49176870211460"

but remember to have running both mosquitto_interface and mosquitto broker.

If you wish to use this in your code you need to import:

import paho.mqtt.client as mc

Operating the Library via Shell Commands

TLE_tracker primarily uses files located in the /var/lib/tle folder. It monitors the most recent file in this directory and extracts TLE lines from it when available.

If the folder does not exist, a warning message will be displayed during tle_tracker runtime. In that case, updating TLE lines is only possible through MQTT topics.

mosquitto_pub -h localhost -t cubesat/tle -m "1 25544U 98067A   20029.54791435  .00001264  00000-0  29621-4 0  9993\n2 25544  51.6434  21.3435 0007417 318.0083  42.0574 15.49176870211460"
mosquitto_sub -h localhost -t cubesat/req_position -m ""
mosquitto_sub -h localhost -t cubesat/req_last_update -m ""

Listening inside your program

In order to get position or time of last update you need:

def __init__(self, broker="localhost", port=1883):
    self.client = mc.Client()
    self.client.on_connect = self.on_connect
    self.client.on_message = self.on_message

where:

def on_connect(self, client,userdata,flags,rc):
        client.subscribe("cubesat/position")
        client.subscribe("cubesat/last_update")

and:

def on_message(self, client, userdata, msg):
        print(f"{msg.topic}: {msg.payload.decode()}")
        if msg.topic == "cubesat/position":
            func_for_what_to_do()
        elif msg.topic == "cubesat/last_update":
            func_for_what_to_do2()

Requesting info inside program

In order to make request for position info:

    def get_pos_info():
        self.client.publish("cubesat/req_position","")

In order to make request for last_update time:

    def get_update_time_info():
        self.client.publish("cubesat/req_last_update","")