Tagged: rtl2832u

WiFi Grid RTL-SDR Radio Telescopes featured in SARA2022 Conference Talks

Over on YouTube the Society of Amateur Radio Astronomers have recently uploaded talks from their SARA 2022 online conference. Two of the talks we've seen focus on describing results produced by small and cheap WiFi Grid RTL-SDR radio telescopes.

Back in early 2020 we first published an article about how it is possible to use get into amateur radio astronomy cheaply using off the shelf WiFi grid dishes, combined with a 1420 MHz LNA + filter, an RTL-SDR and the SDR# software with IF average plugin to measure the galactic hydrogen line.

In the SARA conference we've seen two talks expanding on the use of WiFi grids for radio astronomy. In the first talk Alex Pettit discusses how he's used a WiFi grid attached to an equatorial telescope mount, and a custom modified feed in his setup. In his talk he explains how to use the IF average plugin, and how he uses a MATLAB script to process and plot the saved data.

Alex Pettit: Galactic Hydrogen 1.42 GHz RF Emission Radio Astronomy for $300

In the second talk Charles Osborne describes his "Scope-In-A-Box" which consists of the WiFi Grid, LNA, Filter and RTL-SDR combination and compare the setup versus the same hardware used on a larger 3.7m dish.

Charles Osborne: Comparing Scope-in-A-Box to a 3.7m Dish

If you were interested in those talks, you might also want to check out the other talks from the conference, many of which also involve the use of software defined radios in the receive chain for various amateur radio astronomy experiments.

Decoding Inmarsat STD-C with Command Line Decoder STDCDEC and SigDigger

Over on his YouTube channel Aaron has uploaded a video showing how to use SigDigger and a C based command line Inmarsat STD-C decoder called 'stdcdec' together on his DragonOS SDR based Linux OS image.

STD-C is a marine satellite service that broadcasts messages that typically contain text information such as search and rescue (SAR) and coast guard messages as well as news, weather and incident reports. With the right software, an RTL-SDR and an appropriate L-Band satellite antenna like our 'Active L-Band 1525 - 1660 Inmarsat to Iridium Patch Antenna Set' these signals can be received and decoded.

The stdcdec software provides a way for command line only systems to receive and view STD-C data. In his video Aaron shows an example setup that uses SigDigger to determine the audio frequency offset, and receive the audio which is then passed to the stdcdec software. We note that SigDigger is a GUI based program but could probably be replaced with another CLI based program, in order to run on a headless system (as long as the tuning and audio center freq is determined before hand). Aaron is hoping to explore solutions for this in the future.

DragonOS Focal Rx and Decode Inmarsat-C Messages w/ SigDigger + STDCDEC (RTLSDR)

APT_COLOR: Add False Color to Black and White NOAA APT Images

Thank you to Sasha for submitting news about the release of their latest application called "apt_color". The most popular application for decoding APT weather satellite images from NOAA polar orbiting satellites is WXtoIMG. However, WXtoIMG is closed source and is abandonware. There are APT decoder alternatives, however unlike WXtoIMG most other open source APT decoders only provide black and white images, and do not have a false color feature.

The apt_color application can be used to turn black and white APT images received from NOAA satellites into false color images. Sasha writes:

I am working on an APT false color application here. The application is still in the very, very, early stages but still seems to produce good results. It does not need to rely on any overlays, it simply works off the data you give it - the original decoded image data. I will attach some results. NOAA-18 seems to be the best suited spacecraft for this program.

apt_color: Turn black and white NOAA images into false color
apt_color: Examples

SelfieStick: Combining noisy signals from multiple NOAA APT satellites for clean imagery

Researchers from Carnegie Mellon University have recently presented a paper detailing how they combined noisy signals from multiple passes of low earth orbit (LEO) satellites NOAA 15, NOAA 18 and NOAA 19 in order to create a higher quality image. For a receiver they used a low cost RTL-SDR Blog V3 mounted indoors with a whip antenna.

In a normal setup, weather satellite images from NOAA LEO weather satellites can be received with an RTL-SDR, computing device and an appropriate outdoor mounted antenna that has a good view of the sky. If the antenna is not suited for satellite reception, and/or is mounted indoors, at best only poor quality very noisy images can be received.  

The researchers demonstrate that it is possible to combine noisy images received over time, and from different satellites in order to generate a higher quality image. The challenge is that the different satellites and different receiving times will all produce different images, because the satellites will be at a different location in the sky each pass. They note that simply transforming the images in the image domain would not work very well for highly noisy images, so instead they have devised a method to transform the images in the RF domain. The RF signals are then coherently combined before being demodulated into an image.

The results show that 10 noisy satellite images from the indoor system are comparable to one from a comparison outdoor system. However, they note some limitations in that the system assumes unchanging cloud cover during passes. In the future they hope to extend the system to cover other modulation schemes used by other low earth orbit satellites in order to increase the number of usable satellites.

Selfiestick: Combining noisy images from multiple NOAA satellites received by an indoor RTL-SDR system.

Watch out for new RTL-SDR Blog V3 Counterfeits

Over the past few years our company has been targeted by counterfeiters who copy our RTL-SDR Blog V3 logos and put it on inferior or old RTL-SDR designs. Up until now determining a fake from an original unit has been possible due to obvious differences in the enclosure.

However, we've now recently seen new counterfeit products appearing on marketplaces with enclosures that look almost exactly like our originals. The counterfeit units copy our logos on the front and back, and text exactly. They also now use rounded enclosures, green PCBs and two screws on the side panels. The only real defining features of the more sophisticated clones are that the side panel screws are not diagonally offset, and that there is no NSY QC sticker on the back noting the batch date.

Again, we want to reiterate that anyone can manufacture and sell RTL-SDRs in general as there is no owner of the RTL-SDR idea itself. However we do have our own specific circuit design and trademarked branding that has become popular over the years due to the features and improvements that we designed and implemented whilst still maintaining a reasonable cost. Other manufacturers/sellers should not trick people into thinking they are ordering an RTL-SDR Blog V3 and they should obviously create their own PCB design and branding.

If you want to ensure that you purchase an original RTL-SDR Blog V3 unit, please use the links on our store page to our official global marketplace listings, or the links to our official local resellers (also on the store page), or order direct from our store if your region is supported. Please note that we cannot provide email support or the two year warranty for counterfeit units.

We are doing our best to enforce our trademark and logos on marketplace sites, but it is a never ending task as once one listing is removed, 10 more appear. If you find that you were tricked by a marketplace listing and received a counterfeit, please be sure to report that store and try to get a refund.

Thanks to all our customers and blog readers for your support over the years! We still have a lot of ideas for new products, tutorials and posts and your support helps us keep this all going!

MagicSDR: Streaming Audio over UDP to Decoders like Multimon-NG

Back in May 2021 we first posted about the release of MagicSDR, which is an Android and iOS SDR app that receives data from an rtl_tcp server elsewhere on your network. Apart from the RTL-SDR, MagicSDR also supports the SDRplay, LimeSDR, HiQSDR, Flex 6-seris and sound card based radios.

Recently MagicSDR programmer Vlad wanted to share a new feature in MagicSDR that allows users to stream audio over UDP. He notes that this allows external data decoders such as direwolf or multimon-ng to be used. The example in the video below shows MagicSDR sending demodulated audio over UDP to multimon-ng running on the same Android device.

Decoding Morse CW on android phone

MagicSDR sending demodulated audio over UDP to multimod-ng decoder

An Improved ExtIO for RTL_TCP

Back in 2020 we posted about a modified ExtIO interface which exposed advanced RTL-SDR driver settings such as decimation, manual gain and tuner bandwidth and filtering controls. These features allow users to tune filters to avoid ADC overload and to overall fine tune reception better, especially for narrowband signals. ExtIO is the driver interface used by some popular SDR programs like HDSDR.

Thanks to contributor Ladislav (OK1UNL) for notifying us about an improved version of that ExtIO interface by DG2YCB.

DG2YCB improved version adds the following features:

  • Auto-Q: The RTLSDR stick automatically switches to direct sampling (Q channel) for frequencies below 24.5 MHz and direct sampling is automatically disabled when tuned to any frequencies above 24.5 MHz.
  • My ExtIO_RTLTCP_improved.dll drivers set the chip AGC to ON, which brings you a better RX sensitivity than the original version.
  • My ExtIO_RTLTCP_improved.dll drivers are available in the following versions:
    • ExtIO_RTTCP_improved1.dll uses autoGain for the tuner gain.
    • ExtIO_RTTCP_improved2.dll uses optimized manual gain settings for the tuner gain, which shall prevent that the RTLSDR stick is overdriven on VHF / UHF frequencies.
    • ExtIO_RTTCP_improved3.dll has Auto-Q as well as the optimized gain settings profile but has a more sophisticated GUI, so that you can adjust more parameters manually. (Currently available as beta version.)
       

This ExtIO also allows users to connect to an RTL-SDR when software like HDSDR is run on Linux via an emulator such as WINE.

Ladislav also pointed out that DG2YCB has improved versions of WSJT-X and JTDX that might be of interest to some.

ExtIO Improved dll 3

RTL-SDR Blog V3 Dongle and SDR# Spotted on The Secret of Skinwalker Ranch TV Show

An RTL-SDR Blog V3 dongle and multipurpose dipole antenna set has been spotted in action on the popular TV Show "The Secret of Skinwalker Ranch" in Season 3 Episode 7. Skinwalker Ranch is a History channel conspiracy theory reality TV series where a team of scientists and researchers are sent to look for various explanations for "otherworldly" activities supposedly occurring on the ranch. In the past we have also seen an SDRplay RSP software defined radio with SDRuno software featured in a previous episode.

In this episode the team are drilling into a mysterious mesa rock formation on the ranch, and are monitoring the RF spectrum with an RTL-SDR during the drill. They take note of a mysterious signal at 1.6 GHz that appears during the drilling.

Screenshots from "The Secret of Skinwalker Ranch" Season 3 Ep 7