Category: Applications

TechMinds: Building an Automated NavTex Receiver using a Raspberry Pi and SDRplay

Over on the TechMinds YouTube channel, Matt has uploaded a video tutorial showing how to create an automated NavTex receiver using a Raspberry Pi and an SDRplay software- defined radio.

NavTex is a safety and navigational information radio text broadcast system for mariners, typically broadcast at 518 kHz and 490 kHz. On ships, it is typically received by dedicated hardware that prints out information on a piece of paper as it comes in. However, with an appropriate antenna and an SDR, it is possible to receive and decode NavTex signals at home. 

In his video, Matt shows how a Raspberry Pi loaded with a piece of software created by "boat-comm" can be combined with an SDRplay RSPdx to create a homemade automated NavTex receiver. Matt shows how to install the software and goes on to demonstrate it in action.

Currently, only SDRplay receivers are supported by boat-comms software, but it's possible that in the future, other SDRs may be supported, too.

Automated NavTex Receiver Using A Raspberry Pi & SDRPlay SDR

If you're interested, boat-comm also has a video about his software available on his YouTube channel and we've embedded his video below.

NAVTEX on raspberrypi for sailors

Saveitforparts Checks out the Discovery Dish

Over on his YouTube channel 'saveitforparts,' Gabe has uploaded a video checking out and reviewing our Discovery Dish product that we successfully crowd-funded on CrowdSupply back in December 2023.

Discovery Dish is designed as a low-cost way to dive straight into backyard satellite experiments, including receiving L-band and S-Band weather satellites as well as Inmarsat satellites. It also offers an easy entry into making galactic Hydrogen line observations.

The dish is a 70cm prime focus dish, that can easily be broken down into three parts for easy storage and transport. The feeds are fully integrated, meaning that the feed antenna, LNA, and filtering are all in one unit and built into a waterproof enclosure. This means there is no need to purchase individual components and figure out waterproofing.

In his video, Gabe unboxes the Discovery Dish, builds it, and uses the L-band feed to receive a few images from GOES 16, Meteor M3, Meteor M4, and METOP weather satellites. He goes on to successfully test reception with the S-band feeds on NOAA weather satellites, before testing out the Inmarsat feed and successfully receiving signals. Finally, Gave notes that he hopes to test out the Hydrogen Line feed in a future video.

Checking Out The Discovery Dish - A Simple & Easy-To-Use Satellite Antenna For Everyone!

Locating an Intermittent Interferer with a KrakenSDR

Over on YouTube Thomas Brinkoetter has uploaded a video demonstrating his experience with the KrakenSDR, and how he used it to find an intermittent interferer that he set up for a test. The video was prepared to support the RF Interference and Mitigation class at the IWCE trade show Las Vegas March 17 and 18th 2025.

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 either directly from our krakenrf.com website, or from Crowd Supply or Mouser.

The test involved his wife keying up a repeater for one second out of every 15 seconds. In the video Thomas was able to successfully locate the transmitter with an antenna array and KrakenSDR mounted in his vehicle.

Locating an intermittent interferrer with the Kraken SDR

A Detailed Guide to Setting up RTL1090 for ADS-B Decoding

RTL1090 is a popular ADS-B decoder program that works with RTL-SDR dongles. With it, you can receive ADS-B signals from aircraft, decode them, and then pass that data to a mapping program to plot aircraft positions on a map.

Recently, RTL-SDR.COM reader Frank wrote in and wanted to share with us a detailed guide he's written on the process of setting up RTL1090. The guide starts by showing how to set up the RTL-SDR dongle by installing the WinUSB drivers via Zadig. It goes on to show how to download, unzip, and run RTL1090. Guides for RTL1090 V1, V2, and RTL1090 Scope are shown separately.

RTL1090 Scope
RTL1090 Scope

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

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

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

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.