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Until now, building your own automated weather station to receive NOAA POES or METEOR-M VHF weather satellites was a complex task involving anywhere from 5 to over 12 separate programs, some of which were obsolete, abandoned by their authors and often they'd crash if you looked at them wrong. I won't even mention the difficulty of building an automated HRPT station.

Thanks to SatDump all this pain and suffering can be put to an end, and you can easily build an automated satellite station that can run on a Raspberry Pi or similar device.

This tutorial is designed to replace Linux-based automated stations that used AltiWx or Bash scripts for scheduling, rtl_fm for recording and WxtoImg or Meteor-Detector for demodulation.

If you are looking for a solution to run on a Windows PC (replacing software like SDR#, WXtoIMG and LRPT Demodulator), follow this guide instead.

The basics

If you already had an automated station, you can skip this section and go straight to the Configuration!

I strongly recommend starting manually using the guides I have written, to get the hang of it and also test your equipment and find out if you have noise problems or line of sight limitations.

This is very useful to know your expectations: you will definitely get at least very slightly worse results than if you do everything manually, it's a given for every automated station!

• NOAA POES satellites reception guide
• METEOR-M satellites reception guide

Configuration

Download the latest version of SatDump appropriate for your operating system and install it.

For Raspberry Pi (32-bit Raspbian) I've compiled a ready-made version of SatDump, that can be downloaded here. To download it on the Raspberry Pi itself, type:
wget https://www.a-centauri.com/archivio/Radio/satdump_1.1.4-9cac497_armhf.deb.

Automation behavior

The autotracker can work in both single as well as multiple mode.

Single mode

In single mode, if two satellites pass at once, SatDump will select and receive the one with the highest elevation first, then when the first satellite sets, it will switch to the one with a lower elevation and get the rest of its pass.

This mode cannot receive multiple downlinks from a single satellite (e.g. DSB/APT).

This mode is usually used for HRPT reception with a dish rotator.

Multiple mode

In multiple mode, if two satellites pass at once, SatDump will receive both at the same time (including multiple links, such as DSB and APT). Each satellite recording is completely independent.

This mode cannot receive satellites outside of the SDR's bandwidth. The frequency range is decided by the initial_frequency and samplerate parameters. For example, if initial_frequency is 137.5 MHz (137.5e6) and samplerate is 1e6 (1 Ms/s), the usable frequency range will go from 137.0 MHz to 138.0 MHz.

This mode is usually used for APT/LRPT reception with an omnidirectional antenna.

SatDump configuration

SatDump's command line automated tracker is configured thanks to a JSON file you can put in any directory you like.

Before going on, download the template configuration file to your target system.

Tip: to download it on a Raspberry Pi, type:
wget https://www.a-centauri.com/archivio/Radio/autotrack.json.

I recommend to edit the file with a text editor with automated correction and indentation features. Examples include Geany, Sublime Text, Visual Studio Code, Notepad++ and others.

This is how the configuration file appears before editing.

Configuring your SDR

These parameters control the configuration of your SDR.

• source is the name of the SDR:
  • rtlsdr for RTL-SDR (RTL-SDR V3, Nooelec SMArt/SMArtee, etc.)
  • airspy for Airspy devices
  • hackrf for HackRF originals and clones
  • sdrplay for genuine SDRplay devices (RSP1A, RSPduo etc.)
  • mirisdr for Mirics MSI2500 based SDRs such as RSP1 clones
  • plutosdr for Analog Devices ADALM-Pluto based SDRs (including AntSDR or PlutoPlus)
  • bladerf for BladeRF
  • limesdr for LimeSDR
• samplerate is the sample rate of your SDR. For RTL-SDR, select 1.024e6 which corresponds to 1.024 MHz and is usually adequate.
• gain is the gain of your SDR. YOU MUST SET THIS MANUALLY AFTER TESTING YOUR STATION. DO NOT USE AGC, IT WILL RESULT IN TERRIBLE IMAGES. DO NOT ASK HOW TO ENABLE AGC.
• bias is the bias tee control and can be true or false.

For a list of SDR parameters, see the documentation for more details.

Tip: in the file you downloaded the defaults are already set for a RTL-SDR stick. You only need to adjust the gain and bias tee settings.

Configuring the output folder

The automated tracker will output data from the satellites in the folder set in output_folder. You can set either an absolute path, like /home/example/output, or a relative path to the directory where SatDump was started like in the default config file.

Configuring the location

In order for the automated tracker to work, the location needs to be configured under the qth section.

• lat is the latitude expressed in degrees and decimals of degrees (DD.DDDDDD).
• lon is the latitude expressed in degrees and decimals of degrees (DD.DDDDDD).
• alt is the station's altitude and is expressed in meters.

Configuring the rotator

If you are using an antenna rotator (for example, for HRPT) you can configure it here. For details, see the documentation.

If you are not using a rotator, such as for APT/LRPT, just leave these fields as the default.

Configuring extra parameters

• multi_mode: selects single or multiple mode, where ŧrue is multiple mode and false is single mode.
• stop_sdr_when_idle: stops the SDR and DSP when no satellites are in range (lowers resource and power usage)
• autotrack_min_elevation: if the maximum elevation of a pass is less than this value, the pass will not be recorded.

Selecting and configuring satellites

Tip: if you're only interested in NOAA APT and METEOR LRPT satellites, you can safely skip this. They have already been configured for you.

To select and configure satellites, you need to add an object under the tracked_objects array. Here's a template on what we will work with.

• norad is the NORAD (USSPACECOM or Catalog) ID of the satellite. You can get it from Gunter's Space Page.
• frequency is the frequency of the satellite in Hz.
• pipeline_name is the name of the pipeline. For a list, see the documentation.
• pipeline_params are additional parameters for that specific pipeline. For a list, see the documentation.

Make sure to mind the commas and if unsure use a JSON validator to check your work.

Note that the syntax is different if single or multiple mode is used. The syntax above is intended for single mode.

For further information, please refer to the documentation.

Wrapping up

Save the config file to a directory of your choice with any name you want.

For the purposes of this tutorial, I'll assume it has been saved in your home directory as autotrack.json.

Finishing touches

Test run

It is important to do a test run where you attend the station, verify everything is working as it should, adjust the gain to its optimal level, and check what sort of performance you get.

To run SatDump, type satdump autotrack ~/autotrack.json.

When the AOS is reached on the first satellite, SatDump will automatically switch to it and start the recording as configured (and let you know in the CLI with a red AOS!!!!!!!!!!!!!!!!!!!!!!! message - you can't miss it)

When the recording is done (a red LOS!!!!!!!!!!!!!!!!! message will appear), SatDump will automatically process the data. Wait for the products generation to complete.

Then, stop SatDump (CTRL+C). Everything is ready now to make your station permanent.

Checking the status from a web browser

Did you know you can monitor SatDump with a web browser, because it has an integrated HTTP server?

You can do so by browsing on http://IP_OF_THE_PC_WHERE_SATDUMP_IS:8081, for example if the IP of the Raspberry Pi is 192.168.1.226, then navigate to http://192.168.1.226:8081.

You'll see a web page with all the info about the automated tracker.

Making it permanent

To make it permanent, as well as make SatDump start automatically if the computer or Raspberry Pi is rebooted (ie. due to a power outage), we need to edit a systemd service.

First, edit the service file: sudo nano /etc/systemd/system/satdump-autotrack.service.

Copy these contents into that file and adjust as needed:

Save the file.

Run sudo systemctl daemon-reload to make systemd take the new service into account, then sudo systemctl start satdump-autotrack.

Check the status with sudo systemctl status satdump-autotrack. If you see no errors, go ahead. If not, fix them first (usually they are caused by errors in the config file or wrong paths/users).

Once you are positive it is working, make it permanent by doing sudo systemctl enable satdump-autotrack.

You're done!

Appendix

Editing the autogenerated composites to your preferences

SatDump will autogenerate composites (image type and enhancements) following the master configuration file called satdump_cfg.json as detailed in the documentation page for the composite system.

To override these preferences, such as for example to remove a composite you don't like/need, or to add a personalised one, follow these instructions.

1. Locate the master satdump_cfg.json file. This is usually in /usr/share/satdump/satdump_cfg.json, unless you changed it during the setup phase. Open it in a text editor, such as Textpad or Notepad++.

2. Open the user config file in ~/.config/satdump/settings.json.

3. To disable generating a composite you do not like, go in the appropriate section (avhrr_apt) and copy the name of the composite. Then, set autogen to false.

4. To enable a composite, do the same but set autogen to true.

For further details see the documentation page.

Hardware requirements

While NOAA APT and Meteor-M LRPT will work on basically any Raspberry Pi from Model 3 onwards (except the Pi Zero), HRPT will require a more careful consideration.

A Raspberry Pi 4 is the bare minimum for live HRPT decoding and it will struggle a bit with Metop AHRPT. Switching to a Raspberry Pi 5 is recommended, as it will have no problem handling both HRPT and AHRPT.

Version: v1.0.0