Category: RTL-SDR

TechMinds: One Antenna Four Receivers with an Active Distributor

Over on his TechMinds YouTube channel, Matt has uploaded a video where he reviews a US$20 active antenna distributor that he purchased on Banggood / Aliexpress. An active distributor allows you to use one antenna with multiple radios, without incurring any distribution losses, which for passive splitters are typically at least 3dB per split. It does this by using an amplifier before the splitter. This is especially useful if you have a wideband antenna like a Discone.

The product comes with a built in battery, or it can also be powered via USB-C. Unfortunately it has a rather restrictive frequency range, only covering 100 kHz to 300 MHz.

Later in the video Matt shows the internal PCB of the product, showing its battery and circuitry.

ONE ANTENNA - FOUR RECEIVERS RF ACTIVE DISTRIBUTION

DragonOS: Tracking ADS-B, UAT, ACARS, VDL2 with TAR1090 and a KrakenSDR

Aaron who created and maintains the DragonOS SDR Linux distribution has recently uploaded a new video where he uses a KrakenSDR to simultaneously receive and decode multiple aircraft tracking, telemetry/messaging signals including ADS-B, UAT, ACARS and VDL2.

In the video Aaron uses his WarDragon which is a Mini PC that comes preinstalled with DragonOS. It is currently available on his website for $220, or $550 including a carry case, and Airspy R2.

The video shows how to setup all the software including FlightView GUI which is a graphical user interface that allows users to manage and configure various Docker based aircraft-related services including tar1090, readsb and acarshub.

WarDragon ADS-B, UAT, ACARS, and VDL2 w/ TAR1090 + ACARS Hub (KrakenSDR, Defli optional)

DragonOS: Running GNSS-SDR and Obtaining a GPS Position with an RTL-SDR and Patch Antenna

Over on his YouTube channel Aaron who created and maintains the DragonOS SDR Linux distribution, has uploaded a video demonstrating how to use the GNSS-SDR software together with an RTL-SDR and patch antenna to obtain a live GPS position.

Previously we had only seen a Windows method involving GNSS-SDRLIB and RTKNAVI working as GNSS-SDR on Linux seemed impossible to get running. However, Aaron managed to find a working RTL-SDR configuration for GNSS-SDR which made it come alive. This is great as now GNSS-SDR should be able to run on a portable single board computer like a Raspberry Pi.

The video is a tutorial that shows how to install all the required dependencies, how to compile GNSS-SDR, how to configure it for an RTL-SDR, and how to use it with our RTL-SDR Blog L-band patch antenna.

DragonOS FocalX Setup GNSS-SDR and Obtain GPS Position w/ RTLSDR (Patch Antenna, WarDragon)

SDRx.IO – A Public Server Network for RTL_TCP and/or Spyserver Stations

Thank you to Matt from SDRx.io for submitting a story on our forums about his project called SDRx.IO which is a service that hopes to be a platform that allows remote users to find and connect to public RTL_TCP and/or SpyServer servers. Matt writes:

A few days ago I started a project called SDRx.io. I could not find any platform with public RTL-TCP servers, so I thought I would try to make one for fun.

SpyServer mode (through internet proxy) is also supported. The official map/directory currently does not seem to support this. SpyServer is the default mode, because SDR stations can "somewhat" be shared between multiple clients.

Users can switch radio station modes using the web interface.

SDRx.io routes traffic in a way that protects the actual endpoint from internet exposure, and the server network acts as a CDN (the project currently has 5 servers). Servers can be seen as proxies for radio stations that host the SDR hardware.

The early preview currently on the site only has my own first 2 stations in Switzerland for VHF/UHF, and I am now looking for other users who would be interested in hosting/sharing new radio stations to connect to this project, or participate otherwise.

Required network throughput for RTL-TCP is about 35 mbps at 2.048 MS/s

I know there are already several other projects with public SDR servers, but few carry the full IQ signal, and none are currently providing direct TCP connections compatible with the rtl_tcp protocol.

Your feedback is of course welcome here :D

The service is currently not yet active due a lack of initial interest, but if you are interested you can get in contact with Matt at [email protected].

SDRx.IO Homepage

Automating NOAA APT and Meteor M2 LRPT Reception with SatDump 1.1.2

SatDump is a popular program used to receive and decode various forms of weather satellites, and in recent updates they added support for NOAA APT and Meteor M2 LRPT weather satellite decoding. In the latest 1.1.2 release they have also now added support for automation, amongst many other improvements.

Before this update, to automate the reception and decoding of APT and LRPT satellites a Windows PC, and a huge stack of various decoding and tracking programs and SDR# plugins are required, some of which are now even abandonware.

For APT a typical chain was SDR# -> DDETracker -> Orbitron -> WXtoIMG and for LRPT a typical chain is SDR# -> DDETracker -> Orbitron -> LRPT Demodulator -> LRPT Decoder -> SmoothMeteor -> MeteorGIS. Setting this chain of programs up can obviously be a lot of hard work.

The latest version of SatDump adds automation features which means these two entire chains can be replaced with just one program - SatDump. SatDump is available for Windows, Linux and Mac, so it can even run on something like a Raspberry Pi 5 or Orange Pi 5. 

To help users set up automation, @original_lego11 has written up an excellent tutorial that shows how to set the automation up. Automation involves entering your ground station details and selecting and configuring what satellites you want to receive and decode with your RTL-SDR or other SDR hardware.

SatDump 1.1.2 with the new automation features

Discovery Dish Now Available for Crowd Funding! A Lightweight Dish and Feed for L-Band Weather Satellites, Hydrogen Line and Inmarsat

Today our Crowd Funding campaign for the Discovery Dish has gone live! Thank you to anyone who supports this project and our goal of bringing affordable products that make getting into various radio projects easier.

Our launch announcement reads:

We decided to develop Discovery Dish because we were disappointed by the lack of ready-to-use, low-cost, lightweight dish antennas on the market that are suitable for software-defined radio projects like receiving L-Band geostationary and polar-orbiting weather satellites, as well as for 1.5 GHz Inmarsat reception and 1.42 GHz hydrogen line radio astronomy. With excellent open source weather satellite decoding software, like SatDump, now available, it’s time for a complementary, easy-to-use hardware solution.

Through testing over several years, we chose 65 cm as the diameter, as we found that 60 cm is close to the minimum diameter required for perfect GOES weather satellite reception at 24° elevation, so this size should be suitable for most of the world that has GOES reception available. For LRPT satellites like GK-2A, and HRPT polar-orbiting satellites, it is more than large enough. We combined the dish with a carefully tuned feed that has a built-in low-noise amplifier (LNA) and dual filtering, which means there is no loss from feed to LNA. This also means we can use thinner and less stiff coax cable, which is a lot easier to handle and route. Finally we ensured that the entire dish and feed system is waterproof.

The only other ready-to-use dish offering we found is based on a modified 2.4 GHz grid Wi-Fi dish, which is still in our opinion too big and heavy. Size and weight is especially the important if you want to be able to use a low-cost, light-duty antenna rotator, which typically can only handle less than 1 kg in weight. We found that the grid Wi-Fi dish offering also has no solution for waterproofing the LNA, so the LNA needs to be placed indoors and very thick and unwieldy coax is used to avoid feed to LNA losses.

Other ways to receive these weather satellites and carry out hydrogen line experiments typically involve modifying a 2.4 GHz Wi-Fi grid antenna, or an old satellite TV dish. But these modifications can be time-consuming and difficult to get right, and even 60 cm satellite TV dishes are too heavy for light-duty antenna rotators.

Finally, we developed Discovery Dish with an eye toward it being used with a low-cost antenna rotator, and we are in the process of prototyping our own rotator design. Our antenna rotator is not ready for crowdfunding yet, as there are still some things to work out and long-term stress testing to be done, but please keep an eye out for it in 2024! An antenna rotator is a great addition if you want to use a dish antenna to decode images from the polar-orbiting HRPT weather satellites.

Note that you don’t need an antenna rotator to receive geostationary satellites like GOES, or to do drift hydrogen line observations. For polar-orbiting HRPT satellites, the lightweight nature of Discovery Dish also makes tracking the satellites by hand a much easier prospect.

Learn more about Discovery Dish on our main campaign page. Thank you to everyone who supports the Discovery Dish project in any way!

Discovery Dish: Simplified system for weather satellite reception and hydrogen line radio astronomy

 

Tech Minds: Testing a High Impedance Amplifier for Software Defined Radio

Antenna impedance matching is important for antennas and software defined radios as impedance mismatches can result in poor reception. For transmitting SDR's the situation is more dire because impedance mismatches can actually damage the transmitting hardware or at least cause high power efficiency losses.

Over on his YouTube channel Tech Minds has uploaded a video where he tests out a battery powered HF high impedance amplifier for software defined radios. The amplifier is designed to be used with long wire antennas on the HF bands as these antennas typically have high impedances which don't match the 50 Ohm impedance that most SDRs expect to see. This device is an amplified alternative to using a passive unun.

The results in his video show that the signal to noise ratio is indeed boosted when the impedance matching amplifier is used. Later the device is opened to show the battery, charging management chip and amplifier chip.

High Impedance Amplifier for Software Defined Radio

Radio Field Mixed Reality Visualization with the Quest 3

The Meta Quest 3 is a recently released mixed reality headset from Meta. Recently Manahiyo has ported his RadioFieldAR software to the Quest 3. The RadioFieldAR software allows you to use a radio field probe together with an RTL-SDR or TinySA Ultra, and have the readings visualized in augmented/mixed reality. This could have several real world use cases, for example, probing an electronic PCB and mapping out the RF noisiest parts. Or for visualizing sources of RF signals.

Previously we posted about Manahiyo's work where he used a smartphone to visualize the augmented reality space, and also an older VR headset. Manahiyo writes:

MetaQUEST3, which was recently released, has a color pass-through function and features MR (Mixed Reality). Thanks to this, this software was made possible.

With a smartphone, We took measurements while looking at the antenna through the display, but with QUEST3, we can take measurements in MR (Mixed Reality) using color pass-through features.

In addition, the hand tracking function allows various settings and FFT to be displayed.

It is now possible to take measurements in a more natural and comfortable way.

There are still many bugs, so I'm considering distributing the executable file as before after fixing them.

Manahiyo has not released the software yet, but it appears he is willing to personally distribute the software for testing first. If we receive any further details about software  distribution we will update this post.

UPDATE 29 November 2023: Manahiyo has released the software on Github. He notes:

This software now supports both RTL-SDR and tinySA-ULTRA. Of course, Quest3 is also required. I have provided instructions in the README.md on the GitHub page, which should help you understand how to use it. Currently, only the APK file is available for download. I do not have a plan to open the source code at this time.

RadioFieldMR with the QUEST3 -Measuring noise on FPGA board-

RadioFieldMR with the QUEST3 -Measuring the FM transmitter signal-