Tagged: APT

Updates To NOAA-18 Decommissioning: NOAA-18 Has Now Shut Down

A few days ago, we posted news that NOAA-18 was to begin decommissioning steps effective immediately due to a recent transmitter failure. Multiple reports have now confirmed that NOAA-18 has indeed shut down as of 1740 UTC 06/06/2025.

The usaradioguy.com blog has further updates for those who are interested. The official notice from NOAA can also be found here. Interestingly, it appears that NOAA-18 will not be de-orbiting as it lacks the required propulsion system to do so. So it will remain in orbit as space debris.

A user using a hobbyist station in Sweden also captured the shutdown remotely during APT image reception, as shown in the image below.

Farewell and thanks for your long service NOAA-18!

The final NOAA-18 APT pass captured by SA2KNG in Sweden, and processed remotely by Thomas:douwes.co.uk
The final NOAA-18 APT pass captured by SA2KNG in Sweden, and processed remotely by Thomas:douwes.co.uk

 

NOAA18 to Begin Decommissioning Steps Immediately

In April, we posted news that the NOAA satellites would be classed as 'end-of-life' on June 16, 2025. According to the statements, the satellites were expected to remain in orbit and continue transmitting data that radio hobbyists could use, but no attempts would be made to rectify failures.

However, recent news from Carl Reinmann's usaradioguy.com blog has indicated that NOAA 18 will begin decommissioning steps immediately on June 3, 2025. The steps involve disabling batteries and transmitters, depleting remaining propellants, transitioning data and operations, and finally deorbiting, or moving the satellite to a safer orbit.

NOAA-18 may have been chosen to be decommissioned earlier than NOAA-15 and NOAA-19 as the S-band downlink transmitter failed last month, resulting in severe image degradation. The satellite has also been running on backup gyros since 2017, and has suffered various transmitter and sensor failures over the years. 

NOAA-18

Open-Weather APT: Updates to the Web Based NOAA APT Image Decoder

Dr. Sasha Engelmann and Sophie Dyer, the team behind the Open-Weather project have recently announced the launch of their new version of open-weather apt, a web-based NOAA APT image decoder. The web-based program accepts a WAV file containing a NOAA satellite APT recording, demodulates and decodes it, and displays the resulting weather satellite image.

Sasha writes:

In our recent newsletter, we summarised the updates as follows:

Open-weather apt is the only public, maintained, browser-based decoder for Automatic Picture Transmissions (APT) from satellites NOAA-19, NOAA-18 and NOAA-15. It was developed to improve access to satellite signal decoding for all practitioners.

We are excited to share a new and improved version available here! The new version includes the following updates and additional features:

  • Improved accuracy in decoding and finding sync positions (locates more sync positions than other comparable decoders)
  • Upload a WAV file of any sample rate (no more re-sampling with Audacity!)
  • Option to see the ‘raw’ image without syncing, and to ‘Find the Syncs’
  • Option to Rotate 180 degrees, often useful for viewing images from nighttime passes
  • Go deeper in your analysis: explore Signal Value and Image Value Histograms
  • Upload directly from open-weather apt to the Public Archive

Open-weather apt is co-developed by open-weather with Rectangle (Lizzie Malcolm and Dan Powers), Bill Liles (NQ6Z) and Grayson Earle. We have had a lot of fun testing and experimenting. Please let us know if you have feedback!

Open-Weather APT Web Decoder
Open-Weather APT Web Decoder

IndiaRocketGirl Receives NOAA-19 Weather Satellite Images with a Tape Measure Yagi Antenna

Over on her YouTube channel IndiaRocketGirl (@VU3BIZ) has posted a video showing how she was able to receive weather satellite images from the polar orbiting NOAA-19 weather satellite at 137 MHz.

She uses a home made four element Yagi antenna with elements made from a tape measure. This allows the elements to be easily folded down for transportation. A phone running the Heaven's above app is used to help track the satellite in the sky as it passes over, and then SatDump and an RTL-SDR Blog V3 running on a laptop is used to decode the signal into an image.

IndiaRocketGirl notes that in her next video she will show how to make the Yagi antenna that she was using. In a previous post IndiaRocketGirl also showed how she was able to receive geostationary FengYun-2H S-VISSR signals.

How to Receive Real Time Images from Low Earth Orbit Satellites | India Rocket Girl | NOAA-19

WXCorrector: Updating Keplers for Linux users of WXtoIMG

Thank you to Hamdy Abou El Anein for submitting news about the release of his software called "WXCorrector".  

WXCorrector is a dedicated solution designed specifically for Linux users who face challenges with the handling of Kepler elements in Wxtoimg. This tool addresses a critical issue where incorrect or outdated Keplerian elements can cause disruptions in tracking software, leading to inaccurate predictions and potential data loss.

It work on Linux, it needs sudo rights and Python3 installed.

https://github.com/hamdyaea/wxcorrector-for-linux

WXtoIMG is a commonly used piece of software for decoding images from NOAA APT weather satellites. However,  WXtoIMG is now considered abandonware as the original website has gone, and the main author has not updated the program in many years. The latest versions from 2017 can be downloaded from Archive.org. An alternative download site is https://www.wraase.de/wxtoimg, where they also provide a way to update Keplers for Windows machines.

Due to it's abandonment, certain features like Kepler updates from the internet appear to have broken over time with changes to the way Kepler files are served. Up to date Kepler files are required for the software to know exactly where satellites are in the sky for tracking and scheduling.

A modern alternative to WXtoIMG is SatDump, which now supports NOAA APT satellites.

WXtoIMG

A Satellite Listening Journey

On his Medium.com blog, Mohsen Tahmasebi has posted an article about his journey into listening to satellites which started with his acquisition of an RTL-SDR Blog V3 dongle. The article begins by explaining his motivations for receiving satellites and how difficult hobbies like this are to get into in his home country of Iran. Despite the challenges he tasted success when he was able to receive NOAA APT signals on his second attempt using the included portable dipole antenna in a V-dipole configuration. Shortly after Mohsen was also able to receive Meteor-M2 LRPT.

Mohsen then built a more permanent V-dipole out of copper rods and optimized his antenna using NEC simulation software, finding that adding a reflector significantly improved reception. He then moved on to building a slightly more complex Turnstile antenna, which yielded even better results and allowed him to explore CubeSats at 435 MHz and contribute to SatNOGS. Finally, Mohsen ordered a Bullseye LNB and using a homemade bias tee, he received the QO-100 amateur radio transponder.

Overall, Mohsen's journey demonstrates that there is a lot of fun and learning available from internationally available satellites even in a country where equipment is hard to come by.

Mohsen's First Permanent V-Dipole for NOAA APT Reception

YouTube Satellite Decoding Series

Over on YouTube @dereksgc has been putting together a comprehensive video series on weather, amateur and other satellite reception. His series starts with receiving images from NOAA APT satellites, then Meteor M2, as then goes on to talk about low cost V-Dipole satellite antennas, how satellite dishes work, and recently how to use Ku-band LNBs with a satellite dish.

If you're getting started with RTL-SDR and satellite reception, this video series may be a good introduction for you.

Tracking and Decoding Guide for NOAA Weather Satellites

Thank you to Samual Yanz (N7FNV) for submitting a guide that he's created about tracking and decoding NOAA weather satellites. The guide can be downloaded from this link as a PDF. 

Currently there are three operational polar orbiting NOAA weather satellites that transmit image data in the APT format at 137 MHz. When one of these satellites pass overhead, it is possible to use an RTL-SDR with appropriate satellite antenna and software to receive the satellite weather images they transmit.

Samual's guide focuses on the software and shows how to setup Virtual Audio Cable for piping audio between programs, SDR# for receiving the signal, Orbitron for tracking the satellite and WXtoIMG for decoding the image.

SDR#, Orbitron and WXtoIMG