Over on Reddit Ian Grody (u/DutchOfBurdock) has posted about his success in using a modded Android smartphone to run an RTL-SDR Blog V3 and NOAA decoder software all within the phone itself.
In the past we posted about Ian's work in getting rtl_power scans to work in conjunction with the Tasker app, in order to generate automated frequency scans on his phone on the go. His more recent work from the past year includes showing us how it's possible to install Debian chroot on an Android phone, and run Linux software like GQRX, GNU Radio, DSD, rtl_433, multimon-ng and dump1090 directly on the phone with an RTL-SDR.
His latest Reddit post shows that the NOAA-APT decoder also runs well on the Debian chroot, leading to a truly portable NOAA decoding setup. He notes that he is now working on the possibility of Meteor M2 decoding on the phone.
Below is his video from last year demonstrating SDR GQRX and GNU Radio running on the Debain chrooted phone.
Over on his YouTube channel saveitforparts has uploaded a video showing how he has built an automated weather satellite image collector for the NOAA APT and Meteor M2 LRPT satellites. The video shows a time lapse of him building a QFH antenna, and how he's mounted a Raspberry Pi and RTL-SDR inside a waterproof enclosure attached to the antenna mast. He goes on to show how he's automating the system with the Raspberry-NOAA V2 software.
Automated Home Weather Station (Satellite Image Collector)
Raspberry-NOAA is open source code and a set of scripts that allows you to set up a Raspberry Pi as an automated NOAA and Meteor weather satellite station with an SDR like an RTL-SDR. The software makes use of the Raspberry Pi version of WXtoIMG and meteor_decoder for decoding the satellites, a program called predict for predicting satellite passes, and various automatically generated cron scripts to schedule recording and processing.
Recently V2 has been released by Justin Karimi who builds on the work of the original creators. It seems that the webpanel has been upgraded and made mobile friendly, as well as many more enhancements that can be seen on the Release page notes.
Of course the image is only grayscale (or in Dmitrii's case he decided to use greenscale), but adding false color and various other image enhancements found in advanced software like WXtoIMG are just standard image processing techniques.
Dmitrii concludes with the following:
Interesting to mention, that there are not so many operational radio communication systems in the world, the signal of which can be decoded using 20 lines of code. The NOAA satellites are about 20 years old, and when they finally will retire, the new ones will most likely be digital and format will be much more complex (the new Russian Meteor-M2 satellite is already transmitting digital data at 137 MHz). So those who want to try something simple to decode can be advised to hurry up.
Over on GitHub stdevPavelmc has released his software called FAASGS (Fully Automatic Amateur Satellite Ground Station). FAASGS is an open source program that allows RTL-SDR users to set up a satellite ground station that tunes, record and generate images for NOAA APT weather satellites, as well as records FM amateur radio satellites. The software runs on a single board computer such as a Raspberry Pi, however in the authors own setup he uses an Orange Pi Prime board. The features include:
Web interface to see the next passes, the recorded ones, and details for it.
Receive any satellite in FM mode (SSB is possible but no there is 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 data and receiving station 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
Back in 2017 we posted about Adam 9A4QV's simple V-Dipole antenna design which works very well for receiving NOAA and Meteor weather satellites at 137 MHz. This type of antenna is a lot easier to build compared to a QFH or turnstile, and it results in good performance if built and set up correctly. Over the years he notes that he's received a number of questions asking to clarify the design and so he's uploaded a YouTube video which explains the built and dimensions of the antenna clearly.
In the past we've posted a couple of times about the NOAA-APT decoder software as it is a worthy alternative to the now abandonware software WXtoIMG. However, it lacks certain features which makes WXtoIMG still the go to program for NOAA weather satellite decoding.
As NOAA-APT is open source it has recently seen a few new updates from another contributor, as well as the original author. These changes make it quite a bit more useful, although admittedly not perfect. Hopefully we'll see continued refinement over time. Regardless, this is still a great piece of software which is open source and multi-platform. Martin Bernardi, the original contributor writes:
Although I wasn't planning to continue working in my program, the quarantine happened so I worked on the program a little. Later, a person (Arcadie Z) added more features too, so I created a new version in case you want to add a blog post about it.
Added features since the last blog post:
- Redesigned GUI. - Satellite prediction and map overlay (but has offsets I can't fix yet). - False color images - Histogram equalization (improves the contrast and brightness of images) - Automatic image rotation depending on pass direction
In the end, the map overlay and false color does not work very well, but it is better than nothing I guess.
Back in June we posted about the release of Zbigniew Sztanga's NOAA-HIRS-Decoder which can decode HIRS instrument data which measures the vertical temperature profile of the Earth's surface. This HIRS signal is broadcast by NOAA satellites at the same time as their APT images and the HIRS frequency is close by at 137.350 MHz.
Recently Zbigniew has released a new decoder for the Microwave Humidity Sounder (MHS) instrument which is available on NOAA-19 only. This MHS instrument observes the Earth in the 89-190 GHz microwave band, which can be useful for measuring humidity levels. However, unlike the APT and HIRS signals which downlink data at around 137 MHz, the MHS data is broadcast in the L-band within the HRPT signal, so a motorized or tracked satellite dish will be required to receive it. Zbigniew writes:
The MHS (Microwave humidity sounder) is an instrument on NOAA-18 and NOAA-19. It replaced the older AMSU-B. It has a resolution of 90px per line and 5 channels.
Data from the instrument is present in HRPT and can be decoded with my new software. Unfortunately, only MHS on N-19 is working, because N-18's NHS is dead.
The instrument can be used to monitor low clouds, percipation and water vaopr in the atmosphere. I attached a sample image to the email.