dxlAPRS Encrypted Sonde Telegram Notifier

Sometimes encrypted radiosondes (RS41-SGM) are launched, mainly by the military. Unfortunately, these probes do not reveal their position to the public, but at least the name, frame number and relative received field strength, as well as the frequency can be determined. Since version 1.37b sondemod creates an "alarm" file when one of these sondes gets decoded. This file gets created once on first reception, it contains the serial number and the frequency of the probe. With this Python script, you can send this file and/or it's content autonomously via Telegram from your receiver to your phone. After sending the file and the information to the user, the script deletes the file and waits for the next sonde. The following steps explain how to get the script running. Example of a received Telgram notification:

1. Create a Telegram Bot

1. Open Telegram and search for the "BotFather" bot
2. Start a conversation with the BotFather by typing "/start" and follow the instructions to create a new bot by typing "/newbot"
3. Enter a name for your bot and a username, which should end with "bot" (for example "Encrypted Sonde Notifier" and "encrypted_sonde_notifier_1234_bot")
4. Once you have created your bot, the BotFather will provide you with an API token. Save this token, as you will need it later
5. Define a profile picture, description etc. This is optional
6. If you need help take a look at this tutorial

2. Install needed Libary

To use the script, you need the pyTelegramBotAPI library. The get this library execute the following command in the console.

pip install pyTelegramBotAPI

3. Retrieve the Chat ID of the Bot

After creating the bot, you need to determine the chat ID of the bot. To get the ID, you need to run the script get_chat_id.py. Before you run this script, replace YOUR_API_TOKEN with the actual bot token. Execute the following command in the directory where the script is stored to start the script.

python get_chat_id.py

After starting the script, send a message to the bot (the content doesn't matter) from the mobile or desktop client. After sending the message, the script should print the chat ID.

4. Enable logging of encrypted Sondes

To enable the logging of encrypted sondes, the command which starts sondemod needs to be extended with the -X parameter. An example sondemod start command could look like this.

sondemod -o 18000 -I BAUMI2-15 -r 127.0.0.1:9001 -b 10:5:3 -A 3000:2000:1000 -X /home/dxlAPRS/aprs/logs/encrypt.txt -x /tmp/e.txt -T 360 -R 240 -d -p 2 -M -L 6=DFM06,7=PS15,A=DFM09,B=DFM17,C=DFM09P,D=DFM17,FF=DFMx -t /home/pi/dxlAPRS/aprs/sondecom.txt -v -P JN67FN34RA -N 650 -S /home/pi

5. Insert your API Token in the main Script

Replace the placeholders with your API token and with your chat ID in the main script.

bot = telebot.TeleBot("YOUR_API_KEY")
chat_id = "YOUR_CHAT_ID"

6. Define the Filepath in the main Script

Replace the directory path and filename placeholders in the main script to your parameters.

directory_path  = "DIRECTORY_PATH"
file_name = "FILE_NAME"

For example to something like this.

directory_path  = "/home/pi/dxlAPRS/aprs/logs"
file_name = "encrypt.txt"

7. Define User Variables

This is optional. If you want you can change the value of the following variables to your needs.

callsign = None
position = None
always_send_file = False

For example to something like this.

callsign = "BAUMI2-15"
position = "47.123, 12.123"
always_send_file = True

If you set the value of always_send_file to true the file generated by sondemod will always be sent to you. If this variable is false you only receive the file when the script fails to parse the serial number from the file.

8. Start the Script

To start the script, execute the following command in the directory where the script is stored.

python encrypted_telegram_notifier.py

9. Test Everything

To test if the script is working, place a file where sondemod normally would store a file for an encrypted sonde. After that, start the script. If everything works, you should get a Telegram message with the file attached.

10. Additional Info

To start the script, automatically place the command to start the script in the main script, which starts all other components in the dxlAPRS toolchain to decode radiosondes. The script creates a named process, so you can kill the script easily with all other components to decode radiosondes.

killall -9 getalmd rtl_tcp sdrtst sondeudp sondemod udpbox udpgate4 encrypted-tg-notifier