Saveitforparts: Testing a 3D Printable Satellite Antenna for NOAA, Meteor and other Polar Orbiting L-Band Satellites

Over on the saveitforparts channel, Gabe has uploaded a video showing a 3D-printable helicone antenna for receiving weather images from polar-orbiting L-band satellites like NOAA and Meteor. This antenna has become popular in the community as it is relatively easy to build, lightweight, and small enough to be handheld. The 3D model files are available on Thingiverse.

In the video, Gabe shows that initially, he had multiple failed print attempts on the helical scaffold due to the legs warping. He was able to solve this and get a working print by slightly modifying the 3D model to have additional center supports. He then goes on to show the rest of the build, which involves coiling the helix antenna, cutting the reflector out of sheet metal, screwing together the reflector supports, and mounting the reflector mesh.

Finally, he shows that he was able to get successful image reception from NOAA HRPT satellites using hand tracking, with a phone running an RTL-SDR and SatDump for tracking and decoding.

This 3D-Printed Satellite Antenna Is Fantastic!

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Demonstrating the Effect of Square Wave Harmonics with a HackRF and RTL-SDR

Over on YouTube Paul from 'Tall Paul Tech' has uploaded a video that explains and demonstrates the effect of square wave harmonics using a HackRF and RTL-SDR.

Paul starts by using GNU Radio to explain how square waves are created from a set of sine waves, and how a signal can essentially turn into a square wave if it is too strong and clipping the analog to digital converter (ADC). The result for your SDR is that harmonics of strong signals can show up at incorrect frequencies.

Later in the video, Paul shows this effect using a HackRF and RTL-SDR.

Effect of harmonics and interference from clipping and square waves

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Sn0ren Tests out the KrakenSDR

Over on his YouTube channel, sn0ren has uploaded a video showing his experience with the KrakenSDR. If you weren't already aware, KrakenSDR is our 5-channel coherent radio based on RTL-SDRs, and it can be used for applications like radio direction finding. It can currently be purchased from Crowd Supply or Mouser.

In the video, sn0ren explains radio direction finding in general and then goes on to show how to set up and use KrakenSDR. Sn0ren writes:

Wireless communication is inherently anonymous. There is no way of knowing who transmitted a signal if they do not identify. And there is no way of knowing where that signal is transmitted from. Unless you actively track it down. KrakenSDR is a radio direction finding device that uses an array of antennas and synchronised receivers to track down the position of a given radio transmission and lead you directly to its physical location.

Track Down Radio Transmitters / KrakenSDR

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Saveitforparts: Receiving the Bitcoin Blockchain from the Blockstream Satellite Network

Over on his YouTube channel 'saveitforparts' has uploaded a new video showing how he was able to download the Bitcoin blockchain via the Blockstream Satellite network. The Blockstream satellite network allows people in remote communities without an internet connection to receive the entire Bitcoin blockchain via satellite. With the blockchain Bitcoin users can confirm if a payment to them has been made.

After several failed attempts, he was finally able to receive and decode the signal using a fold-out satellite dish with an LNB and an RTL-SDR Blog V4. He also attempts to use the encrypted messaging feature on the blockstream satellites. However, while the message appears to have been received, he was unable to actually view the message due to an error. He writes:

A while back I heard about the Blockstream Satellite network, which claims to offer real-time streaming of the Bitcoin blockchain to anyone with a satellite dish. While I still don't understand cryptocurrency, I thought the satellite part of this sounded interesting!

It took a while to locate the correct satellite (Galaxy 18 in North America), and to get the software working, but eventually I was able to start downloading the blockchain file. What to do with it next, I have no idea!

I also tried sending messages through the satellite, but unfortunately I wasn't able to decode them on the receiving end. I gave up on this since I didn't want to spam everyone on the global network!

You can find out more about the Blockstream Satellite system on their website: https://blockstream.com/satellite/

And you can find instructions on using the system here:https://blockstream.github.io/satellite/doc/sdr.html

I used https://www.dishpointer.com/ to help align my antenna.

I also used https://www.lyngsat.com/ and https://www.satbeams.com/ to identify which satellites I was detecting.

I Found Bitcoin On A Satellite In Space

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SignalSDR Pro: An Upcoming SDR with 70 MHz to 6 GHz, 12 Bit ADC, 61.44 MHz Bandwidth and 2TX/2RX Channels

Over on CrowdSupply, a new software-defined radio called the 'SignalSDR Pro' made by Hong Kong company Signalens has recently been announced. The SignalSDR Pro is roughly the size of a credit card or Raspberry Pi and has a 70 MHz to 6 GHz tuning range, 12-bit ADC, 61.44 MHz of bandwidth, and 2RX/2TX channels.

The SDR is based on the AD9361 chipset, used by several other SDRs, including the PlutoSDR and Ettus USRP B210. It also comes with an AMD Zynq 7020 FPGA. Of note is a feature that allows the device to emulate a PlutoSDR and USRP B210, instantly making it compatible with software written specifically for those devices.

In the video below, creator KaiJern Lau introduces the SignalSDR Pro and explains the motivation behind creating it.

The project is currently in the pre-crowdfunding stage, and you can sign up for updates on its Crowd Supply page. 

The SignalSDR Pro
The SignalSDR Pro
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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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