What is the project weather satellite ?

This is a tool that automates image retrieval that weather satellites send by radio.

The goal of this project is to help radio amateurs who are just starting out to collect satellite images.

Example of images retrieved :

Running in a raspberry pi 4

A linux image with the software of this project is already ready. You just need to install it with the following commands on the raspberry pi sd card:

SD card detection:

norian@norian-HP-Pavilion:~/Documents/github/Weather-Satellite$ lsblk

NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
...
sda           8:0    1  14,8G  0 disk 
├─sda1        8:1    1  61,2M  0 part /media/norian/boot
└─sda2        8:2    1   2,7G  0 part /media/norian/root

Unmounting the sd card

norian@norian-HP-Pavilion:~/Documents/github/Weather-Satellite$ umount /dev/sda?

Copy image to card

You can find the Linux image for the raspberry pi 4 in the image folder.

norian@norian-HP-Pavilion:~/Documents/github/Weather-Satellite$ sudo sh
norian@norian-HP-Pavilion:~/Documents/github/Weather-Satellite$ bzcat radio-image-raspberrypi4-64-20220507193544.rootfs.wic.bz2 > /dev/sda

Connection to the raspberry pi 4 by UART

norian@norian-HP-Pavilion:~$ lsusb
...
Bus 001 Device 009: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port

norian@norian-HP-Pavilion:~$ modprobe usbserial vendor=0x067b product=0x2303

norian@norian-HP-Pavilion:~$ dmesg | grep 'ttyUSB0'
[  566.914757] usb 1-1: pl2303 converter now attached to ttyUSB0

norian@norian-HP-Pavilion:~$ sudo chmod 777 /dev/ttyUSB0

norian@norian-HP-Pavilion:~$ screen /dev/ttyUSB0 115200

The login is root.

Running on PC

You can compile the software for your Ubuntu machine using the makefile present in the src folder.

How to use the project

Hardware

This program has been tested with a DVB-T COFDM rtl2832U demodulator and a dipole antenna. I also made a system image for a Raspberry pi 4 with yocto.

	Here is a link to the antenna image blog

How to use this software

First way

Create a file for each recording you want to make on your raspberry. The file must contain the following elements:

• name
• frequency in Hz
• Recording start date in format month, day, hour, minute, seconde (mm-dd-hh-mm-ss)
• Recording end date in format month, day, hour, minute, seconde (mm-dd-hh-mm-ss)

ex:

norian@norian-HP-Pavilion:~/Documents/github/Weather-Satellite$ nano noaa

noaa19
137910000
02-13-08-31-00
02-13-08-37-00

norian@norian-HP-Pavilion:~/Documents/github/Weather-Satellite$ radio-exec noaa19

You can also add a watchdog in minute to make sure raspberry pi power off:

norian@norian-HP-Pavilion:~/Documents/github/Weather-Satellite$ radio-exec noaa19 -w 36000

Second way

Just launch the software on your raspberry and follow the instructions:

norian@norian-HP-Pavilion:~/Documents/github/Weather-Satellite$ radio-exec
Please enter the number of satellites: 
2
Would you like to set a watchdog ? (press y or n) 
y
Please enter the watchdog value (in minutes)
600
Please enter the name of the satellite 
noaa19
Please enter the frequency (in Hz)
137910000
Enter the start date of the revolution (format = mm-dd-hh-minmin-ss) 
02-13-08-31-00
Enter the end date of the revolution (format = mm-dd-hh-minmin-ss) 
02-13-08-37-00

Please enter the name of the satellite 
noaa18
Please enter the frequency (in Hz)
137912500
Enter the start date of the revolution (format = mm-dd-hh-minmin-ss) 
02-13-10-16-00
Enter the end date of the revolution (format = mm-dd-hh-minmin-ss) 
02-13-10-29-00

At the end of the recording a wav file is generated. You can then convert the file to an image with the wxtoimg software.

How to retrieve information from a satellite? (frequency, date of passage ect...)

You can retrieve the information needed to configure the software using gpredict.

Go to Files -> New Module.

Add the satellites you want to listen to and validate. / ! \ For the moment only communications by FM modulation are supported by my project. My project has only been tested with satellites communicating with the APT standard.

Right-click on the satellite you want to listen to and select Future Passages.

You then see the start date of the pass, the end date and the maximum elevation for the pass of the satellite.

To obtain the listening frequency, double click on the satellite and go to the Transponders menu.

Running of the software

The parent process creates a child process for each record and uses a message queue to send them their parameters.

When the recording time is reached and if the rtl2832U board is available, the child process starts recording. When recording is complete, the child process terminates.

The parent process detects the end of a child process by capturing the SIGCHLD signal.

When all child processes are finished then the parent process powers off the system.

A log file is generated during the use of the software allowing you to know what happened during the recording.