Investigating the Transit 5B-5/E-5 Satellite: The oldest satellite still transmitting

Transit 5B-5 is a US Navy navigation satellite that was an early version of the GPS/GNSS system we enjoy today. It was launched in 1964 and has been transmitting continuously for roughly 60 years. Unlike many dead satellites that only emit a carrier tone, this one still broadcasts modulated telemetry on about 136.65 MHz, making it a fascinating target for amateur radio and SDR hobbyists.

Over on YouTube dereksgc has uploaded a video that is a deep dive into the Transit satellites, and tries to unravel the convoluted naming scheme. In the video, dereksgc digs into historical documents and compares orbital decay rates, modulation schemes, and expected signal formats.  The results strongly suggest that this “Transit 5B-5” signal may actually be coming from a different spacecraft altogether, likely “Transit 5E-5.” 

Detailed SDR recordings and analysis of its subcarriers and data rates reveal that the format, frequency, and stability align better with the Transit 5E series rather than the navigation-oriented Transit Oscar series as previously believed.

If you are interested in receiving Transit 5B-5/5E-5, you can do so with a simple RTL-SDR and 137 MHz antenna, which is commonly used for NOAA and Meteor weather satellite reception. We have posted about receiving Transit 5B-5/5E-5 before on this previous post too.

The oldest satellite still transmitting (and its complicated identity)

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Running RTL-SDR in your Browser via an HTML5 App

Thank you to Jacobo Tarrio for writing in and sharing his latest project, an HTML5-based RTL-SDR application that runs directly in your browser. Jacobo writes that he'd previously created a Chrome app called FM Radio Receiver for Chrome (which we also posted about previously), but unfortunately, Google stopped supporting Chrome apps.

Jacobo goes on to write:

Last year I started working on it again. I took the original source code, modernized it to use modern TypeScript and HTML5 APIs, and then transformed it deeply to turn Radio Receiver into a general-purpose RTL-SDR application (with a waterfall and everything), which is available at https://radio.ea1iti.es/.
 
You don't need to install anything -- it runs straight on your browser. (Well, you still need to do the usual RTL-SDR driver setup, but other than that...)
 
It supports any computers or Android phones with the Chrome, Edge, or Opera browsers. Unfortunately, it cannot run on iPhone or iPad, or on the Firefox or Safari browsers.
 
For hardware, it works well with the RTL-SDR Blog V3 and V4 sticks (with support for direct sampling on the V3 and for the built-in upconverter on the V4), as well as other R820-based sticks.
 
The source code is available on GitHub under the Apache 2.0 license.
RTL-SDR running in an HTML5 web browser app
RTL-SDR running in an HTML5 web browser app
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Updates to Knowle Consultants RTL-SDR Android Apps

Thank you to James Mainwaring, who wanted to write in and share that he has made some updates to his suite of Android apps, which include ADS-B Radar (RTL-SDR), FM Radio (RTL-SDR), Airband Radio (RTL-SDR) and HAM FM Radio (RTL-SDR).

James notes that all his apps now support the ability to connect to an rtl_tcp instance running remotely. He also writes that the ADS-B app now automatically downloads and displays photos of the aircraft being tracked via the API connection to planespotters.net.

ADS-B Radar (RTL-SDR) Android App now shows aircraft images.
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Building a ‘WiFi Camera’ with a HackRF and Helical Antenna on a Motorized Pan-Tilt Mount

Recently, "The Thought Emporium" YouTube channel uploaded a video showing how they have created a 'WiFi Camera' using a HackRF and helical antenna mounted on a motorized Pan-Tilt mount.

The Thought Emporium has actually already done this experiment back in 2018, as seen in a previous post; however, in the latest video, they iterate on the design, releasing a new open-source 3D printable version.

The idea behind the 'WiFI camera' is to point the directional helical antenna in different directions using the motorized mount and measure the WiFi signal power using the HackRF at each spot it points towards. Each measurement results in a heatmap pixel, and once enough pixels have been collected, an image is formed.

This Camera Can SEE WiFi

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DragonBridge: Streaming IQ Data Over 802.11ah HaLow via Two Relay Drones

Aaron, creator of DragonOS, has uploaded a video on his YouTube channel showing him testing out long-range communications via 802.11ah Wireless Networking and a T-HaLow bridge on two drones. 802.11ah (aka HaLow) is a WiFi protocol designed for long range IoT communications of up to 1 km (without obstructions).

In the video, Aaron attempts to stream IQ data with SDR++ over 802.11ah HaLow from a Pi + KrakenSDR operating over 1.6km away. The communication is established via two drones in the air that act as a relay bridge between the two ground stations. Although there are issues with keeping the connection stable, these experiments serve as a great first test of this capability.

Join me on an exciting month long+ journey as I push the boundaries of wireless communication using the Lilygo T-HaLow 802.11ah devices in bridge mode! In this video, I demonstrate how I successfully established an SSH connection from my laptop, across six T-HaLow units—some mounted on two drones and others on the ground—to a Raspberry Pi ground station equipped with DragonOS pi64 and a KrakenSDR.

What You'll See:

Innovative Network Setup: I configured three pairs of T-HaLow units, each pair consisting of an access point and a client. The first pair connected my laptop to the first drone. On each drone, I bridged two T-HaLow units via Ethernet, effectively creating a relay system. The second pair connected the two drones, and the third pair linked the second drone to the ground station Raspberry Pi.

Successful Long-Distance Communication: By the third attempt, I achieved a stable ping across the entire bridge and streamed IQ data from the SDR++ server on the Raspberry Pi to the SDR++ client on my laptop—over a distance of 1.6 km between drones!

Challenges and Triumphs: Experience the hurdles I faced, from connectivity issues to environmental obstacles, and how perseverance led to a successful connection.

Stunning Aerial Footage: Enjoy breathtaking drone shots that not only showcase the technology but also add a visual treat to the technical journey.

Why This Matters:

This project highlights the potential of increasing the standoff distance between equipment using 802.11ah technology, also known as Wi-Fi HaLow. Operating in the sub-1 GHz unlicensed bands, 802.11ah offers extended range and improved propagation through obstacles compared to traditional Wi-Fi frequencies. It's designed for low-power, long-range connectivity with lower power consumption—ideal for IoT applications, remote deployments, and innovative projects like this DragonBridge.

Equipment Used:

Building the DragonBridge: Long-Range 802.11ah Wireless Networking with Drones and T-HaLow Devices

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A Tutorial on Setting up a XHSI Cockpit Display with Live Data from an RTL-SDR Receiving ADS-B

Back in 2017, we first posted about using a program called RTL1090-XHSI which is used to display a simulated aircraft cockpit using live data acquired directly from an RTL-SDR receiving ADS-B flight data from nearby aircraft. The ADS-B signal provides not only position and heading data but also information about altitude and speed, which is then used to simulate the cockpit display.

Recently Al wrote in and wanted to share with us a step-by-step tutorial that he has created that shows how to set this up. The guide shows how to download, install and use all the software programs required.

XHSI Cockpit Display with Live ADS-B Data Received by an RTL-SDR
XHSI Cockpit Display with Live ADS-B Data Received by an RTL-SDR
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HOPE XV Conference 2024: Ham Radio for Hackers Talk Video

Back in July 2024 we posted about Dan's (KB6NU) talk at the HOPE (Hackers of Planet Earth) conference about how Ham radio can be for hackers, and how hackers are the future of ham radio. Back then only the slides were available.

The video of the talk has recently been uploaded to YouTube, and is embedded below. The talk emphasizes how ham radio is not only about the traditional thought of making contacts, which is probably in most people's heads, but also about hacking radios, antennas, microcontrollers, satellites, pico balloons, digital communications, GNU Radio, and more. Dan mentions his goal is to promote ham radio to the much younger hacker crowd, where he believes it is underrepresented.

HOPE XV (2024): Ham Radio for Hackers

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Creating an SDR from a TEF6686 Car Radio FM/AM Chip

A recent IEEE Spectrum article details how hobbyist PE5PVB has repurposed an NXP TEF6686 automotive FM/AM tuner chip into a software-defined radio with a tuning range of 65 MHz - 108 MHz and 144 kHz - 27 MHz.

PE5PVB developed custom open-source firmware for TEF6686 dev boards, allowing them to tune beyond their original design frequency range. He then went on to develop a version that included a screen. Eventually, the Chinese manufacturers caught on to the potential of the design and are now producing a full handheld version that is available on Aliexpress at a current sale price of US$61.26.

Reviews of the product are all positive, and it appears to be one of the best choices for a portable handheld DXing radio.

A TEF6686 based SDR available on Aliexpress.
A TEF6686 based SDR available on Aliexpress.
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