Fully Automatic Amateur Satellite Ground Station

A setup to build a satellite ground stations that can tune, record and generate images for FM and APT weather satellites.

This is the software recipe, in the hardware part I used an Orange Pi Prime Board but you can use any Single Board Computer, including Raspberry Pis (Note: see section "Installation note in Raspberry Pi OS"), O-droids and even a normal PC or Server.

The only advice is to use one with a multiple cores and at least 1GB of RAM as some task are resource intensive.

I used Armbian as OS, but you can manage it to make it work with RaspiOS or any other linux distro with a little of work.

A sample of the main view:

A sample view of a pass of PO-101 DIWATA-2B (FM sat):

A sample view of a pass of a NOAA weather APT satellite:

Inspiration

This project is inspired and heavily based on the work of Luick Klippel and his work on his NOAA Satellite Station repository.

Features

• Web interface to see the next passes, the recorded ones, and details for it.
• Receive any satellite in FM mode (SSB is possible but there is no doppler control yet, so no SSB by now)
• Record the satellite pass and keep the audio for later.
  • APT WX audio is preserved in wav format and 22050 hz of sampling (the format wximage needs to work with)
  • FM audio satellites is preserved in .mp3 mode but with high quality settings, and other tricks.
  • The spectrogram of the audio is embedded as album art (see below).
  • The pass details and receiving station data are stored in the mp3 tags.
• Automatic decode APT images from WX sats (NOAA 15, 18 and 19)
• For the voice FM sats we craft a spectrogram and embedd the metadata of the pass on the image.
• NEW selection for audio processing schema: streamed or step by step (first is good on fast or dedicated systems, the former on slow or multitasking ones) see users.conf while installing for more details.

Future features?

• Migrate to python3 for the main processing (doppler adjust, aka SSB tracking/recording?)
• Control a rotor via Hamlib.
• Craft a solution to allow for doppler corrections while receiving (will allow to receive SSB signals, at least for CW beacons)
• Improve the mobile experience (responsive web) WiP...

Installation steps

Warning: all the installation steps mentioned here needs root privileges, typically just making a sudo -s in the console to gain root is enough, or you can type sudo before any command.

pre-installation requisites

As this tool relies on many tools I will not explain how to setup each one, but I will give you clues of where to get info about it.

• Web server + PHP support

You need a web server with php installed (at least version 7.x, no MySQL or MariaDB support needed), google has a lot of guides indexed, just google for "install nginx and php in [your-operating-system]"

RaspiOS users: If the web server works but does not process php files (try to download the index.php file instead of process & show) you must take a peek on this tutorial about how to enable php support for nginx.

• Predict

You need to install predict the software to make predictions of satellite passes.

For RaspiOS / Raspbian:

sudo apt install predict

For Armbian you need to compile it from source, you can get it from the Predict home page.

After installing predict you need to do this aditional step to make it run properly (install some files):

sudo -i
mkdir /root/.predict
cd /root/.predict
wget https://raw.githubusercontent.com/kd2bd/predict/master/default/predict.db
wget https://raw.githubusercontent.com/kd2bd/predict/master/default/predict.tle
wget https://raw.githubusercontent.com/kd2bd/predict/master/default/predict.qth
# Next step only if using a Rasberry Pi board
ln -s /root/.predict /home/pi/.predict

• WXtoImage

This wonderful piece of software was deprecated by the original authors but a group of enthusiast keep it alive in the Restored WXtoImage site.

Just download it here: WXtoImage deb package for ARM or browse the site for other architectures.

To install it copy it to your SBC computer and run (Debian based distros):

sudo dpkg -i wxtoimg-armhf-2.11.2-beta.deb
# [ignore errors if any]
sudo aptitude install -f
# [this will fix any dependency error listed above]

As I mention this software is abandonware and if you search on the site you will find a generic register credentials.

To register the software in the SBC you need to install it on a linux box with an GUI (can be another SBC or a real linux box); run xwximage and fill your coordinates and settings, register with the credentials and just then locate a hidden file under your home directory called .wxtoimgrc and copy it to /root/.wxtoimgrc in the SBC. You are done.

• Utilities

You need at least git and make, in most linux (including SBCs) you are set by running this:

sudo apt install git make

• Installation note in Raspberry Pi OS

For some unknown reason the rtl_fm tool lacks the -E wav option as @takagiwa found, the solution is to compile the rtl-fm from upstream, see this comment for details.

Real install

• Login in your into SBC and clone this repository git clone https://github.com/stdevPavelmc/FAASGS.
• Change to the created folder cd FAASGS.
• Gain root access via sudo -s
• Run configuration steps make cconf.
• Configure your local data (see Configuring below)
• Run install script make install.
• Execute it by hand to check if all works sats.sh.
  • Go to your IP address and check if there is any 'next pass' scheduled.
• If all gone ok, run the schedule script to make it run for good make permanent

Configuring

After the configure step you need to modify your local data, you callsign (use N0NAME if you are not a ham radio operator), name, locator (use this tool if you are in doubt), coordinates (use locator tool to check the coordinates too), QTH and the satellites you want to capture.

Just go to /etc/sat_data and edit a file named user.conf with the command sudo nano user.conf to fill your data.

You will find a proxy setting there to, if you don't use a proxy just leave it as is, if you use a proxy then follow the comments.

Next step is to select the satellites you want to monitor, the file is named sats.json and it has a very common web format, you can add or remove sats as your need.

Use sudo nano sats.json to edit the file, it came by default with all the working NOAA satellites and the working VHF ones, but if you have a dualband antenna you can introduce some UHF sats also.

Please note that the satellites has a name and a nickname, the name refers to the one that appears in the TLE file and the nickname is a friendly name for us (and must not contain spaces, parenthesis, slashes, etc)

Upgrading

This software is designed to be upgradeable with little eforts, just follow this steps:

• Login into your SBC and change to the folder you cloned the repository in the past.
• Gain root access via sudo -i
• Update the software with this command git pull if there is an update you will be notified about the files that has changed.
  • If you get a warning about it can merge the data, just do this git reset --hard tha twill reset the tree then repeat the git pull.
• Clean the workspace with this command make clean
• Install the new version of the software make install.
• Make it permanent with make permanent.

Removing

If you need to remove the software there is a command for that make remove, but all the collected data will be preserved in the /var/www/html/sat folder, you will be warned about it.

A word about the RF part: Antennas!

I have not spoken about antennas and RF in this document because that relies on your expertice, I will mentioned my experience with some and I trust your internet skills to find them

• A 2m J-pole: normal for voice FM sats, bad for APT images (the image of PO-101 above was taken with just a J-pole + 12m of RG-8X)
• A horizontal 120 degrees V for APT satellites (137 Mhz): better for APT, regular-to-bad for voice FM satellites
• A 1/4 wave 2m ground plane (120 degrees elements) regular for 2m voice, regular for APT and regular-good for 70cm sats (yes, it works on 70cm too)
• The mentioned V + a custom VHF wide LNA (about +8 dB on 137 and 145 Mhz): very good for APT, normal-to-good for voice FM sats (actual antenna I'm using now)

As usual, the higher and un-obstructed view for the antenna the better, also for coax: top quality ones and as short as possible.

This is FREE SOFTWARE!

Free as in freedom, no payment are needed, see the LICENCE file for details.

If this is software is of any utility to you; please consider to make a donation to keep me improving it, see Contributing file for details.

Contributing

You can improve the software, appoint bugs or fails, donate equipment or money, top up my cell phone, or just share your impressions on social media; details for all of that in the Contributing file.

Any contribution is welcomed.