Tagged: rtl2832u

A Tribute to Amateur Radio Astronomer Job Geheniau (Job’s Radio Telescope)

Job Geheniau was someone whose amateur radio astronomy projects were often featured on RTL-SDR Blog (often referred to as Job's Radio Telescope). It with great sadness that we have recently learned that Job Geheniau passed away from cancer in late December 2023. We would like to take the time share this post to highlight some of his achievements in the amateur radio astronomy field.

Back in 2020 Job first surprised us with one of his first radio astronomy results (Part 1, Part 2) where he was able to image the Milky Way in neutral hydrogen by using a 150cm dish, RTL-SDR, LNA and motorized mount. Over eight nights he recorded hydrogen line readings throughout the Milky Way and ended up creating a 2D Excel sheet that showed an image of the Milky Way at the 1420 MHz hydrogen line frequency. 

Job would go on, rapidly evolving and each time showing us that low cost hardware set up in a backyard could be used to unlock many of the secrets of the universe. Using a satellite dishes less than two meters in diameter, RTL-SDRs, LNAs and filters he was able to:

Job's Radio Astronomy website remains up at https://jgeheniau.wixsite.com/radio-astronomy, and many results and writeups of his other experiments can be found there. We will sorely miss posting about Job's achievements, but we hope that his life has inspired you to take a closer look at the amateur radio astronomy hobby.

A tribute to Job will also be published in the next membership journal from the Society of Amateur Radio Astronomers.

Modified RTL-SDR Source for SDR++ with Manual Controls for R820T/2/R828D Tuners and Harmonic Reception

Over on GitHub user Sultan-papagani has just released a modified RTL-SDR source for SDR++ that enables full manual control of the gain stages, filters and other features on R820T/2/R828D tuner based RTL-SDRs. This includes the Blog V3 and Blog V4. In the standard drivers many of these these features are automatically controlled.

Tweaking the individual LNA, Mixer and VGA gain stages manually can help you to maximize SNR, while adjusting the filters can help block out of band interference.

The modified source also enables the 'Hamonic reception' enhancement from the librtlsdr fork of rtl-sdr, which allows you to tune up to 6 GHz via harmonic mixing. Note that tuning above the standard maximum of 1.766 GHz will most likely require strong band pass filtering and an external LNA as the harmonic mode results in a lot of imaging and weak signals. 

A new RTL-SDR Source for SDR++ with Manual Gain/Filter and Harmonic Mixing Controls
A new RTL-SDR Source for SDR++ with Manual Gain/Filter and Harmonic Mixing Controls

The Biggest RTL-SDR and Related Stories from 2023

This year there were several interesting stories and product releases that we posted about on the blog and this post will be a brief end of year review of some of our most popular posts. We also wanted to wish everyone a Merry Christmas and Happy Holidays to every celebrating at this time of the year!

In January we saw that the popular ADS-B Exchange (ADSBx) ADS-B aggregation platform was sold to a private equity firm called JETNET. This caused quite a bit of outrage as many involved with the development of the platform were blindsided by the owner's sudden decision to sell. ADS-B Exchange is a popular ADS-B aggregator that uses RTL-SDRs and is known for it's hard no censorship policy, allowing it to be used in projects like "Dictator Alert" and to uncover immoral use of aircraft in policing and military "kill chains". Many of the original team have since started a new service at https://airplanes.live.

ADSBExchange.com interface
ADSBExchange.com interface

Next in February at the height of the "Chinese Spy Balloon" scare we ran a story about how the US air force had shot down an amateur radio 'pico balloon' called K9YO-15  , on the assumption that it could have been another Chinese spy balloon. Pico balloons are party sized helium balloons with a solar powered amateur radio transmitter attached. The fun of the hobby is seeing how far and long around the world they can travel for. A typical pico balloon could circumnavigate the globe several times over several months, all whilst transmitting it's position.

Rough trajectory overlay
Rough trajectory overlay

In April we saw the Flipper Zero go mainstream when it was reviewed on the Linus Tech Tips YouTube channel. The Flipper Zero is a small RF hacking device that gained high popularity on social media sites like TikTok. 

Linus Tech Tips Reviews the Flipper Zero
Linus Tech Tips Reviews the Flipper Zero

In June we saw a video from a YouTuber that appeared to show a Flipper Zero being used to wirelessly 'let the smoke out' and self-destruct an electricity meter which raised major infrastructure security concerns. However, this video appears to have since been removed, and there was speculation that the video was faked, or at least staged in some way.

In July we showed a video demonstration of how our KrakenSDR could be used to track down a low power FM transmitter station. In August we showed the KrakenSDR tracking down multiple GSM base station transmit towers simultaneously.

Later in August we also released the RTL-SDR Blog V4 dongle, a limited edition RTL-SDR that makes use of existing stockpiles of R828D tuner chips. It has improved HF performance thanks to an upconverter, and improved filtering on the VHF and UHF bands.

In September we saw crowd funding start for the RFNM, a device that promises to be a next generation software defined radio.

Finally in November we saw the release of the crowd funding campaign for our Discovery Dish project, a low cost and easy way to get into reception of L-band satellites, as well as Hydrogen Line radio astronomy.

Later in November we also saw a great technical overview of the Watch Duty wildfire monitoring project which uses multiple RTL-SDRs in their system.

The Discovery Dish
The Discovery Dish

A WSPR Monitor Running on an old Android TV Box with OpenWebRX and RTL-SDR

Thank you to Joseph IT9YBG for writing in and sharing with us his experience in getting Armbian and OpenWebRX running with an RTl-SDR V3 smoothly on an old A95X Android TV Box. These TV Boxes have an AMlogic S805 chip and Joseph writes that he is quite impressed by the performance of the chip.

To install the Armbian Linux operating system Joseph used the instructions from i12bretro and installed OpenWebRX after. Then together with his RTL-SDR Blog V3 dongle he turned the device into a cheap dedicated WSPR (Weak Signal Propagation Reporter) monitor allowing him to free up his Raspberry Pi 3 which was used for the task previously.

IT9YBG's Android TV Box converted into a WSPR monitor with an RTL-SDR Blog V3 and OpenWebRX
IT9YBG's Android TV Box converted into a WSPR monitor with an RTL-SDR Blog V3 and OpenWebRX

A 3D Printed Enclosure for RTL-SDR Blog V3/V4 Units

Thank you to Dave D. for submitting his 3D printed enclosure for RTL-SDR Blog V3 and V4 units. The enclosure is designed to protect and support the dongle. It includes an optional hole for a heatsink to keep the unit cool. Dave writes:

I've designed a 3D printed case for the RTL-SDR Blog V3 & V4. The reason for the case is to use a USB extension to move the weight of the device from the PC USB port to make portable laptop use less likely to fall out or break.
 
Additionally, there is an opening in the case top to accommodate an optional heat-sink, which may be beneficial with the V3 at higher frequencies.
 
Here's the link to the 3D print files free on Prusa's Printables website. Anyone can download and print this. Creative Commons applies
 
Dave's 3D printed enclosure for RTL-SDR Blog V3/V4 units with optional heatsink.
Dave's 3D printed enclosure for RTL-SDR Blog V3/V4 units with optional heatsink.

A Great Introductory Video to RTL-SDR

Over on YouTube user sn0ren has posted a well produced introductory video to RTL-SDR. If you're already familiar with software defined radios and RTL-SDR, this video won't be of any use to you, but if you are just starting out, or have friends that might be interested, this is a great video to show.

Sn0ren's video goes over basic concepts like the history behind RTL-SDR, what an SDR is, what radio is, and then goes on to explain and demonstrate reception of the various different types of  signals that can be received with an RTL-SDR and compatible software.

The Cheapest Radio Receiver For Beginners / RTLSDR v4

Tech Minds: Making your own SDR Software With GNU Radio Companion

In his latest video out on YouTube, Matt from the Tech Minds channel gives us an overview of GNU Radio, and shows a few examples of how it can be used to receive, transmit and decode digital data.

GNU Radio is a popular open source DSP framework for software defined radios. With it you can graphically implement any sort of digital signal processing chain that you like, which can be used for decoding/encoding and demodulating/modulating signals.

GNU Radio can be extremely complex and powerful, but in the video Matt shows some simple starter example flowgraphs like an LSB demodulator, and a simple wav file source transmitter for the HackRF. 

How To Make Your Own SDR Software With GNU Radio Companion

Downloading Stored Images and Data from the NOAA Weather Satellite GAC Broadcast

With polar orbiting weather satellite reception we as amateur ground station operators with SDR receivers typically download images via "Direct Broadcast", which provides imagery of what the satellite is currently seeing live. However, the main way satellites such as the NOAA POES (NOAA 15, 18 & 19) satellites downlink is via "Global Area Coverage" (GAC) broadcast which provides the full stored imagery data of the entire global pass. However, GAC is only broadcast in locations where the satellite operator operates ground stations.

Over on YouTube dereksgc has uploaded a video showing how to receive GAC data from the NOAA POES satellites. He notes that GAC is now broadcast at 2247.5 MHz in the S-band, and the ground station it now downlinks to is likely in Svalbard, rather than in the USA. This means that amateur satellite stations close to the North Pole can receive the GAC signal, including dereksgc's station which (we believe) is in the Czech Republic.

Dereksgc uses a large 250cm offset dish with S-band feed connecting to a HackRF. In the video he demonstrates him receiving the signal, and then decoding it using SatDump. Finally he shows all the images from various locations around the earth that he was able to receive from one satellite pass.