Category: RTL-SDR

The Open-Weather Project’s Year Of Weather: June 15 NOAA EOL Nowcast Scheduled

Dr. Sasha Engelmann and Sophie Dyer, the team behind the Open-Weather project have recently announced a NOAA end-of-life nowcast to be recorded on June 15 2025. An open weather nowcast is a collaborative effort with users all around the world sending in weather satellite images that they have received locally with their home SDR setups.

NOAA satellite weather image APT transmissions have long been a staple of RTL-SDR hobbyists as they are among the easiest and cheapest satellite transmissions to receive. A simple V-dipole, RTL-SDR, and a computer are all that is required.

Sadly, it was recently announced that the NOAA satellites will be classified as end-of-life (EOL) on June 16 2025. However, the good news is that APT and HRPT data transmissions are expected to continue as usual. The end-of-life status indicates that NOAA will cease its own collection of data from these satellites and, hence, will no longer be distributing the datasets online. It also means that the satellites should no longer be used for mission-critical or scientific purposes and that no attempt will be made to fix a failing satellite.

These satellites have been operating well past their operational life, and given their advanced age, failure could come at any time. So the Open-Weather nowcast on June 15 2025 remains a nice way to honor their service to humanity.

You can see the last Year of Weather map created by the Open-Weather team and contributors here https://open-weather.community/yow/map/

The recent newsletter from the Open-Weather team explains how to participate in the June 15 nowcast.

OpenWeather Current Screenshot
OpenWeather Current Screenshot

New Khanfar Software: RTL-SDR CFAR Mask Analyzer

Recently, software developer M. Khanfar has been releasing a lot of new SDR and RTL-SDR compatible software, which you can see by searching for Khanfar on our blog.

Recently M. Khanfar has released a new program called "Khanfar RTL-SDR CFAR - Mask Analyzer" which is software designed for RF signal detection and analysis. Khanfar writes:

This powerful tool combines advanced Constant False Alarm Rate (CFAR) algorithms with innovative  Frequency Mask Trigger (FMT) techniques to provide reliable signal detection even in challenging RF environments.

CFAR (Constant False Alarm Rate) is an advanced adaptive threshold technique developed originally for radar systems but extremely valuable for any signal detection application.

The Frequency Mask Trigger (FMT) functionality allows you to define signal-free areas in the spectrum where you expect no signals or want to ignore existing signals. The software automatically adapts to these masks, preventing false detections in known signal areas while maintaining high sensitivity in areas of interest.

What You'll Learn:
How CFAR adapts to changing noise environments
Impact of different algorithm parameters
Mask creation and application techniques
Optimal settings for different signal types

Perfect For:
Students learning signal processing
Radar enthusiasts and researchers
SDR hobbyists exploring advanced features
Engineers developing detection systems

The Khanfar RTL-SDR CFAR - Mask Analyzer brings many features traditionally found only in expensive commercial spectrum analyzers and radar systems to the affordable RTL-SDR platform and provides an incredible value for education, hobbyists, and even many professional applications.
The software was also soon after updated to support Airspy devices, and add Telegram integration. The Telegram integration allows users to set up remote monitoring, and have alerts and data delivered directly to your mobile device via the Telegram messenger chat software.

As mentioned in previous posts, antivirus software can flag M. Khanfar's software as suspicious. We suspect these are false positive results due to the PyInstaller system used to create the exe, but please take your own precautions just in case.

Khanfar RTL-SDR CFAR - Mask Analyzer

 

RTL-SDR Provides Vital Information during Portugal & Spain Blackout

Over on LinkedIn Khalil A. has uploaded a short post highlighting how critical monitoring radio communications was during the mass power outage in Spain. This week Spain and Portugal experienced country wide blackouts, leaving more than 55 million people without power for more than half a day.

During the blackout, news was difficult to obtain as mobile services and internet connections failed. Khalil used a charged laptop and an RTL-SDR to monitor FM, AM, amateur, and emergency services, providing up-to-date information to his neighbourhood.

RTL-SDR provides news during Spain and Portugal blackouts
RTL-SDR provides news during Spain and Portugal blackouts.

NOAA 15, 18, 19 End of Life Announcement – But Transmissions will Continue for Hobbyists

Over on the USradioguy.com blog, we've seen news from Carl Reinmann noting that NOAA 15, 18, and 19 will be classed as end-of-life on June 16, 2025. These NOAA satellites are ones commonly used by RTL-SDR hobbyists to download weather satellite images, either via APT on 137 MHz with a V-dipole antenna, or via HRPT on 1.7 GHz with a tracking dish antenna.

Initially, it was thought that this meant that transmissions would cease. However, Carl Reinmann has now clarified with NOAA that transmissions of the APT and HRPT signals will continue as usual. Importantly, NOAA urges that these transmissions will only be "data of opportunity" and should no longer be used for operational purposes (not for anything safety-critical, for example). The transmissions will be fine for everyday hobbyist use.

However, this does mean that should the sensors on these satellites start failing, no attempt will be made to repair them from the ground, and in case of critical failures, the satellites will be decommissioned. In the past, we've seen NOAA 15's scan motor fail multiple times before coming back to life. It's not clear if the satellite received commands from the ground that helped recover it or if the motor just recovered by itself.

The NOAA satellites have lived well past their operational life.
The NOAA satellites have lived well past their operational life.

Hearing Lightning with an RTL-SDR

On YouTube, user MatdoFM has uploaded a video demonstrating what lightning sounds like over the radio and how to receive lightning pulse noise using an RTL-SDR.

When lightning strikes it releases a pulse of electromagnetic radiation, which shows up as a short wideband noise pulse over the radio spectrum. Lightning detection and mapping services like Blitzortung use a network of volunteer run VLF receivers spread out across the globe to determine the location of lightning pulses using time of arrival radio direction finding techniques.

In the video, MatdoFM uses a frequency of 124 MHz. Because the lightning pulse noise is so wideband, it extends from VLF to VHF and sometimes even UHF frequencies. At the end of his video, MatdoFM shows a lightning strike captured with his security camera and the corresponding radio sound produced by that strike.

Hear LIGHTNING With Your RTL-SDR!

Receiving Elektro-L3 LRIT Weather Satellite Images with an 11-Turn Helix Antenna and No Dish

Typically, a satellite dish is used to receive Elektro L3. As an example, our 70cm diameter Discovery Dish with linear feed can do this easily, and achieve an SNR of about 5-6 dB. However, as Meti shows, it is possible to receive this satellite even without a dish, and as he shows, an SNR of 1.5 dB is sufficient for decoding a perfect image.

Meti's antenna is an 11-turn RHCP helix made of copper wire, with a 17 x 17cm ground plane. In his post, he also notes a few interesting findings, noting that the height of the antenna off the ground is critical, rotating the helix can help, interference from cell towers can cause issues, and bending the corners of the ground plane can help.

In the rest of the post, Meti also shows how well the helix antenna works at receiving weather satellite signals from polar orbiting L-Band satellites like Meteor M2-3.

Meti's 11-Turn RHCP Helix Antenna
Meti's 11-Turn RHCP Helix Antenna

New Khanfar Software: Spot Scanner, Phased Based DF, IQ Playback

Recently, software developer M. Khanfar has been releasing a lot of new SDR and RTL-SDR compatible software including a Spectrum Analyzer and FM demodulator, directional antenna based radio direction finder, and a gr-phosphor based spectrum visualizer.

His pace of development continues, and recently he's developed three new programs.

The first is Khanfar Spot Scanner, a tool for detecting active signals. 

Khanfar Spot Scanner is a powerful and feature-rich spectrum analyzer designed for radio frequency enthusiasts, wireless security researchers, and professional RF engineers. Supporting multiple SDR hardware devices including RTL-SDR, Airspy, and HackRF, this software provides comprehensive spectrum visualization, automated signal detection, and in-depth analysis reporting.

Khanfar Spot Scanner

The second software is called "Khanfar Phase-Based Direction Finding" a tool for phase based radio direction finding.

Khanfar Phase-Based DF is advanced direction finding software that uses phase difference analysis to determine the bearing of radio signal sources. Unlike traditional direction finding systems that rely on directional antennas and signal strength comparison, this software utilizes an array of omnidirectional antennas and sophisticated signal processing algorithms to analyze the phase relationships between received signals.

We want to add to this a note that we're not entirely sure how this software can possibly work as phase based direction finding with RTL-SDRs requires synchronized clocks, and sample and phase alignment to be performed via a correlation with a noise source first which this software does not enable. Without those steps taken results will be totally random. We gave this software a brief test with a KrakenSDR, but as expected, did not see the results we expected. We're keen to hear feedback from other users.

Khanfar Phase-Based Direction Finding Software

The third program is called "Khanfar IQ Live-Rec-Playback" a tool for recording and playing back IQ files, with IQEngine integration.

Khanfar RTL-SDR IQ Live+Rec+Playback is a powerful, feature-rich spectrum analyzer application designed for RTL-SDR devices. This professional-grade software provides real-time RF spectrum visualization with GPU-accelerated rendering, comprehensive IQ data recording capabilities in multiple industry-standard formats, and advanced playback features for signal analysis. With IQEngine and IQ Analyzer integration, you can seamlessly export your recorded signals for comprehensive online analysis, visualization, and collaboration.

Khanfar IQ Live-Rec-Playback

GOES-19 Completes Transition to GOES-EAST Replacing GOES-16

NOAA GOES satellites are a popular way to receive beautiful full-disk weather images of the Earth using an RTL-SDR, antenna hardware such as the Discovery Dish, and software such as SatDump. The GOES-EAST satellite covers North and South America and was provided by GOES-16 until April 7th.

Over the past few months, NOAA has been moving the GOES-16 satellite into a storage orbit and the newer GOES-19 satellite, which was launched in June 2024, into the GOES-EAST position. Recently, on 7 April 2025, this transition was completed, and the GOES-16 was turned off, and the GOES-19 signal was activated.

For SatDump users, no configuration changes should be necessary to receive signals from GOES-19. However, Sanchez users will need to update their configuration file.

If you're interested, Carl Reinmann, owner of the usradioguy.com website, provides more detailed information about the transition and activation of GOES-19.

GOES-19 Received by Carl Reinmann
GOES-19 Received by Carl Reinmann