Over on YouTube, Tom the Dilettante has uploaded a video demonstrating how to receive HF signals with an RTL-SDR Blog V3 running in direct sampling mode. This is something already known to most RTL-SDR fans, but on the RTL-SDR V3 we have built in a direct sampling circuit that enables reception below 24 MHz with a simple settings change in software.
In the past and with other dongle brands, enabling direct sampling required hardware mods involving directly soldering a wire antenna to very small pins or pads. Direct sampling is not a high performance mode for HF, but in many situations it can be good enough for casual listening.
In his video Tom demonstrates HF reception with the RTL-SDR Blog V3 and an MLA-30 active loop antenna. This is a cheap loop antenna available on Aliexpress that works very well for the price.
Listen Around the World - No Internet Required (HF & Shortwave on RTL SDR)
NASA's Radio Jove is a project that enables students and amateur scientists from around the world to observe and analyze the HF radio emissions from Jupiter, our Sun and our galaxy using easy to construct HF radio telescopes that receive spectrographs from 16-24 MHz. The project has existed for more than two decades, and these days the telescope builds mostly make use of low cost software defined radios.
In a presentation for the Society of Amateur Radio Astronomers (SARA) Richard Flagg & Jim Sky talk about what sort of hardware is used these days for the Radio Jove project. They note that SDRs like the Softrock, Funcube Dongle Pro+, SDR-IQ, SDR-14, RTL-SDR, and RASDR have been used. They go on to discuss some of the spectrograph logging software that is used with the project as well.
The presentation slides in PDF form can be found here.
Richard Flagg & Jim Sky: Radio Jove Spectrograph Hardware and Software (RJ10/11)
Over on his YouTube channel "saveitforparts" has in the past created a portable homemade 'tricorder' which was a boxed up Raspberry Pi with multiple sensors including an RTL-SDR. One new application he's found for the tricorder is the ability to detect the beacons from Starlink satellites using the RTL-SDR and an LNB.
Starlink beacons typically transmit at around 11.325 GHz, so to receive them with an RTL-SDR a downconverter and antenna such as an LNB is required.
In the video he demonstrates the hardware in use, and shows some of the beacons being received on the spectrum, via the tricorders built in LCD screen.
SatDump is a popular piece of software that can be used with RTL-SDRs and other software defined radios for decoding images from a wide array of weather imaging satellites including GOES, GK-2A, NOAA HRPT, FengYun, Electro-L and Meteor M2 LRPT + HRPT, and many others (note: there is no APT support at the moment, but it is planned for the future). It is compatible with Windows, Linux and even has an Android APK available.
Over on the Frugal Radio YouTube channel Rob has uploaded part two of his two part series on the KrakenSDR. The KrakenSDR is our 5-channel coherent radio based on RTL-SDRs, and it can be used for applications like radio direction finding and passive radar. We successfully crowd funded the device on Crowd Supply.
In the first video Rob unboxed the KrakenSDR and set up the software. In this second video he takes the KrakenSDR out on a drive and is able to successfully locate the transmission sources of two unknown transmitters.
In the first part of the video Rob shows how he sets up his vehicle roof antennas and how he routes his cabling into the vehicle and KrakenSDR. He then shows his drivers view as he locates the site of a DMR trunked network user which ends up to be a factory plant. In his second test Rob locates a P25 transmitter site. In both tests Rob notes how he was impressed at how quickly a location was able to be determined, taking only a few minutes each time.
KrakenSDR - WOW! Amazing Direction Finding Tests : Part 2
ATAK (Android Tactical Assault Kit) is an Android app used by some branches of the US military for visualizing geospatial information such as enemy and friendly positions, as well as any other information of interest. The civilian version of ATAK (CivTAK) was recently open sourced in 2020 and can be downloaded from the Google Play Store.
The software has a huge number of features for coordinating teams, planning operations and visualizing information. It can even network via handheld, or ham radios or a Meshtastic LoRa network if a central server and internet connection is unavailable. Of note is that their plugin page references the possibility of using a plugin that uses RTL-SDR hardware for ADS-B aircraft tracking. However, it appears that the plugin needs to be purchased from tak.gov. We suspect that in the future there will be more RTL-SDR compatible plugins available.
FlightAware is a company that specializes in distributed ADS-B aggregation, in order to produce real time maps and information about what aircraft are in the air. In 2021 FlightAware was acquired by Collins Aerospace, which is a subsidiary of Raytheon Technologies, a large US aerospace and defense contractor.
Most of the data that FlightAware obtains comes from volunteers all around the world running an RTL-SDR dongles on their Raspberry Pi based image. The dongles receive the ADS-B 1090 MHz broadcasts from aircraft which contain information about the aircraft including GPS location.
Back in 2016 they released the FlightAware ProStick, which is an ADS-B optimized RTL-SDR with onboard 1090 MHz LNA. Later in 2017 they released the Prostick Plus which improved performance in high interference areas due to the addition of a 1090 MHz SAW filter.
Their post goes into more detail about their products, and note that they are currently designing a new Prostick Plus with filter placed before the LNA instead of after. They also discuss how they are looking into higher end 12-bit ADCs for their receiver hardware, and at creating a dual channel receiver for the 978 MHz UAT band as well. They then go on to discuss the software architecture behind the ADS-B decoder they use.
Over on YouTube F4IPO has posted a video of him using a KrakenSDR and the KrakenSDR Android mapping app to quickly locate the source of a TETRA transmission at 427 MHz in France.
The KrakenSDR is our 5-channel coherent radio based on RTL-SDRs, and it can be used for applications like radio direction finding and passive radar. We successfully crowd funded the device on Crowd Supply.
In the video F4IPO shows a dash cam recording of his vehicle alongside a screen recording of his Android phone screen. He makes use of the auto-navigation feature which navigates him right to the radio transmit tower. He notes that the entire process to locate the transmitter only took about 5 minutes. At the end of the video he shows the antenna setup on his roof.