Thank you to RTL-SDR.COM reader Micha for submitting a story about how he has been able to use SDR# and the Airspy Server Network to explore cable TV stations across the globe via cable TV signal interference.

If you were unaware, the SDR# software from Airspy.com has access to the Airspy Server Network, which is a collection of public Airspy SDRs available all over the world that can be accessed freely over the internet. To access these SDRs simply select "Airspy Server Network" as the source in SDR#, and click on the "..." button next to the server address entry. A map will pop up where you can select from SDRs all over the world.

Using Airspy SDRs in Russia, and in other countries (Guatemala, Brazil, Chile, Uruguay, Mexico, Dominican Republic, Argentina, Indonesia, Vietnam, Micha found that there were several analog TV signals found at frequencies that should not have terrestrial TV signals there. Upon further investigation, he realized that these are actually cable TV signals that are leaking and causing interference across the RF bands. Micha notes that he's also observed how the leaking signals often change in frequency and intensity too, making it difficult to keep track of them.

Combined with the TVSharp SDR# plugin, Micha was able to recover some (very rough) images from these interfering signals. Micha has provided several images shown below that demonstrate Russian cable leakage, as well as for Mexico and Argentina.

Last month we posted about Aaron's video on Meshtastic, and how it's possible to decode the Meshtastic protocol using an RTL-SDR and GNU Radio project called Meshtastic_SDR. 

If you weren't aware, Meshtastic is software that enables off-grid mesh network based communications and can run on cheap LoRa hardware. The mesh based nature of the system means that communications can be received over long distances, without any infrastructure, as long as there are sufficient Meshtastic nodes in an area that can route the message to the destination node. One example application of Meshtastic is to use it as a mesh-based text messaging system. This might be useful for teams of hikers, pilots, or skiers who operate in remote areas without cell phone coverage.

In his latest video, Aaron shows how Meshtatsic_SDR can also be used to transmit the Meshtastic Protocol using a transmit capable SDR like the HackRF. Aaron writes in the video description:

In this video, we take a deeper dive into the setup and usage of the meshtastic_SDR repository, which now enables the transmission and reception of Meshtastic using Software Defined Radios (SDRs). Recent updates have made this possible by partially leveraging GNU Radio flow graphs for both RX (receive) and TX (transmit), and integrating Python scripts that connect to ZMQ sources for message input and ZMQ outputs for message decoding.

I demonstrate the setup using a HackRF for the transmit side and an Airspy R2 for receiving. We also verify the results of TX and RX using a standard Meshtastic receiver to ensure accurate performance.

In his latest video, Matt from the TechMinds YouTube channel tests out an LHCP L-band helix feed designed for receiving Inmarsat satellites. Matt pairs the feed with an 85cm satellite dish, an L-band LNA, and an Airspy Mini.

The L-band helix feed comes from a small German engineering company called nolle.engineering. The feed is priced at 94.70 Euros (incl. VAT) (~$102 USD), plus shipping costs. It is a passive antenna so it needs to be combined with an LNA to be usable with a typical SDR.

In the video Matt shows that the reception with the LHCP helix + dish setup is better than expected. He also compares it to a previous test he did with a longer RHCP helix antenna also produced by nolle.engineering. The RHCP antenna is used to be used without a dish, however, as expected the SNR is less than the dish + small LHCP feed setup. Matt then shows some Inmarsat signals being decoded including STD-C and Aero voice.

Paolo Romani (IZ1MLL) has recently released the 2024 version of his SDR# Big Book. The book is available for download on the Airspy downloads page, just scroll down to the title "SDR# Big Book" and choose your language. (At the time of this post only English and Italian are available in the 2024 edition, but multiple languages are available for the older guides).

Paolo writes that the book has been updated for the latest SDR# v1920 version, and now the editions will be labelled by date, instead of version number. He also writes that page 25 of the big book now includes information about the differences between RTL-SDR Blog V3 and V4 dongles. 

Airspy is currently holding their annual summer sale which gives 15% off their line of products until June 30 2024. The sale brings the price of the popular Airspy receiver products down to the following in US dollars (note that actual pricing may vary across local resellers):

• Airspy R2: $169.00 $143.65
• Airspy Mini: $99.00 $84.15 
• Airspy HF+ Discovery: $169.00 $143.65
• Airspy SpyVerter R2: $49.00 $41.65
• YouLoop Antenna: $39.95 $33.95

The sale is active at all participating resellers, which includes our own store where we have the YouLoop on sale for US$33.95 including free shipping to most countries in the world. 

Some good reviews of the YouLoop include the YouTube videos done by Frugal Radio where he reviews HF reception and VLF & LF reception with an Airspy HF+, and later tests it with an RTL-SDR Blog V3 using direct sampling. Techminds also has an excellent review on his YouTube channel. 

If you are on Twitter/X, make sure to also retweet the sale post for a chance at winning something.

Over on Twitter/X @lamdbaprog, creator of Airspy products and the SDRSharp software has teased his next upcoming software-defined radio hardware called the "Airspy HF+ Ranger". The Airspy HF+ Ranger prototype was also seen at the Dayton Hamvention through their local Airspy.us reseller.

The specifications appear to be very impressive, with a wide frequency range of 0.5 kHz to 1750 MHz and excellent sensitivity, linearity, and dynamic range figures. The Ranger is based on the same main RF chips used in the HF+ Discovery, so it will retain the relatively small maximum bandwidth capability of 710 kHz. However, for many use-cases this small bandwidth is more than sufficient.

Currently, there is no word on a release date or pricing but given the prototype status, it must be close. We expect this to be priced higher than the Airspy HF+ Discovery which sells for US$169.

Update: A page for the Airspy Ranger is now on the Airspy website. It shows a block diagram and further details. RTL-SDR.COM reader Ladislav has also sent us a PDF with the specs and a Dynamic Performance graph.

Over on Twitter/X, patrons of the Dayton Hamvention event have posted a few pictures of the display.

@lamdbaprog also demonstrates the incredible dynamic range of the Ranger when up against strong pager signals in Paris.

Over on his YouTube channel, Rob VK8FOES has started a new video series about Iridium Satellite Decoding. Iridium is a constellation of low-earth orbiting satellites that provide voice and data services. Iridium was first decoded with low cost hardware by security researchers back in 2016 as mentioned in this previous post. Being unencrypted it is possible to intercept private text and voice communications.

Rob's video is part of a series, and so far only part one has been uploaded. The first video outlines the hardware and software requirements for Iridium decoding and demonstrates the gr-iridium software. An Airspy and RTL-SDR Blog Patch Antenna are used for the hardware, and the software runs on DragonOS.

Rob writes that in part two he will demonstrate the use of iridium-toolkit, which can be used to extract data and recordings from the Iridium data provided from gr-iridium.

Be sure to subscribe to his YouTube channel so that you are notified when part two is released.

The Airspy YouLoop is a no tune, broadband, small footprint, affordable LF to HF receive antenna that works indoors. Its modular construction facilitates experiments to understand where the Möbius inspired electrical design provides benefit.

The post Airspy YouLoop LF/MF/HF Möbius Receive Antenna appeared first on Ham Radio . Magnum Experimentum.