During September 26 - 30 GNU Radio Conference 2022 was held in Washington DC. GNU Radio Conference (aka GRCon) is an annual conference centered around the GNU Radio Project and community, and is one of the premier software defined radio industry events. GNU Radio is an open source digital signals processing (DSP) tool which is used often with SDRs.
A few days ago videos of all the presentations were released on their YouTube channels, and all the talks can be found on this playlist. The videos contain a mix of in person and remote talks. A schedule of all talks can be found on the GNU Radio website.
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 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.
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.
Job's latest work has seen him detect Pulsar B0329+54 with his 1.9m dish and an RTL-SDR. He writes:
A pulsar is the rapidly spinning and pulsating remnant of an exploded star.
PSR B0329+54 is a pulsar approximately 3,460 light-years away in the constellation of Camelopardalis. It completes one rotation every 0.71452 seconds and is approximately 5 million years old
Everything indicates that I may have been able to detect the pulsar B0329+54 with JRT [Job's Radio Telescope]. This dish has a diameter of 1.9 meters, which would make it the first time (!) this pulsar has been detected with a dish of this size as far as I can tell. This result was obtained thanks to the good help and software of Michiel Klaassen.
Over on Facebook Job Geheniau has recently described his success in detecting interstellar high-velocity clouds with his telescope consisting of a 1.8 meter dish, amplifiers, band pass filters, and an RTL-SDR.
High-velocity clouds or HVC's are areas of interstellar gas that are moving at very high velocities relative to that of the galactic rotation.
His latest post about detecting high velocity clouds reads:
CIII High Velocity Cloud detected with 1.8 meter JRT.
The receiver was a RTLSDR connected to some amplifiers, band pass filter and a 1.8 meter dish.
HIGH VELOCITY CLOUD CIII with JRT (Job’s Radio Telescope)
Wikipedia: “High-velocity clouds (HVCs) are large collections of gas found throughout the galactic halo of the Milky Way. These clouds of gas can be massive in size, some on the order of millions of times the mass of the Sun and cover large portions of the sky. They have been observed in the Milky Way's halo and within other nearby galaxies.
HVCs are important to the understanding of galactic evolution because they account for a large amount of baryonic matter in the galactic halo. In addition, as these clouds fall into the disk of the galaxy, they add material that can form stars in addition to the dilute star forming material already present in the disk. This new material aids in maintaining the star formation rate (SFR) of the galaxy.
The origins of the HVCs are still in question. No one theory explains all of the HVCs in the galaxy. However, it is known that some HVCs are probably spawned by interactions between the Milky Way and satellite galaxies, such as the Large and Small Magellanic Clouds (LMC and SMC, respectively) which produce a well-known complex of HVCs called the Magellanic Stream. Because of the various possible mechanisms that could potentially produce HVCs, there are still many questions surrounding HVCs for researchers to study.”
For JRT the High Velocity Clouds are pretty hard to detect.
The Anti Center Complex is the easiest which I detected earlier last year.
This week I tried C III. It’s at Galactic Coordinates 120 50 and has a Vlsr of -140 km/s. You can find it on the chart:
In the simulation it looks like this:
Pay attention the low Brightness Temperature (0.3 Kelvin) compared for instance with Deneb (80 Kelvin)! Pretty hard to detect with my dish.
With JRT I did a 4 hour exposure (also 4 hours of Darks in the neighborhood) at 1420.405 MHz.
The new Feed I built is very good and has a perfect ‘pitch’ at gain 25 dB.
The final result for High Velocity Cloud CIII with my 1.8 meter dish:
Job Genheniau's projects have been featured several times on this blog in the past for imaging the Milkyway and other astronomical objects like supernova's and protostar regions with a 1.8m radiotelescope dish and RTL-SDR or similar SDR.
In his latest achievement Job has noted that he has had some limited success in observing NML Cygni with his dish and an Airspy Mini SDR. NML Cygni is a 'red hypergiant' star situated within the Cygnus constellation, and it is one of the largest stars by radius known. Prior observations have found that it exhibits a spectral line at 1612.231 MHz.
Job's setup consists of his 1.5m dish (extended to 1.8m with mesh) on a rotor, a custom feed tuned for 1612 MHz, a 0.47dB NF low noise amplifier, an RF filter and an Airspy Mini SDR. Observations were made in SDR# and plotted with Excel.
The NML Cygni hypergiant is difficult for amateur's to observe, and Job notes that he is not aware of anyone previously observing it with a 1.8m dish. He notes that he had 20 failed attempts, but 5 recordings that stood out as possible successes.
However, ultimately Job has been unable to claim that the star was successfully observed, but his results to appear to show some possible success. He notes that some of the uncertainty stems from the fact that on some recordings he observed the peak at the expected -25 km's blueshift expected from the star, however other recordings had the peak at the wrong blueshift.
SDRAngel is a general purpose software defined radio program that is compatible with most SDRs including the RTL-SDR. We've posted about it several times before on the blog, however we did not realize how much progress has occurred with developing various built in plugins and decoders for it.
Thanks to Jon for writing in and sharing with us a demonstration video that the SDRAngel team have released on their YouTube channel. From the video we can see that SDRAngel now comes stock with a whole host of built in decoders and apps for various radio applications making it close to an all-in-one SDR platform. The built in applications include:
ADS-B Decoder: Decodes aircraft ADS-B data and plots aircraft positions on a map
NOAA APT Decoder: Decodes NOAA weather satellite images (in black and white only)
DVB-S: Decodes and plays Digital TV DVB-S and DVB-S2 video
AIS: Decodes marine AIS data and plots vessel positions on a map
VOR: Decodes VOR aircraft navigational beacons, and plots bearing lines on a map, allowing you to determine your receivers position.
DAB+: Decodes and plays DAB digital audio signals
Radio Astronomy Hydrogen Line: With an appropriate radio telescope connected to the SDR, integrates and displays the Hydrogen Line FFT with various settings, and a map of the galaxy showing where your dish is pointing. Can also control a dish rotator.
Radio Astronomy Solar Observations: Similar to the Hydrogen line app, allows you to make solar measurements.
Broadcast FM: Decoding and playback. Includes RDS decoding.
Noise Figure Measurements: Together with a noise source you can measure the noise figure of a SDR.
Just a few days ago we posted about Job Geheniau's success at radio imaging the Cygnus-X star forming region at 1424 MHz with a 1.9m radio telescope, an RTL-SDR and some additional filtering and LNAs.
Now in his latest post on Facebook Geneniau has also shown that he has successfully imaged Cassiopeia A with the same equipment. Cassiopeia A is a supernova remnant known for being the "brightest extrasolar radio source in the sky at frequencies above 1 GHz" [Wikipedia]. Geheniau writes:
A new observation from JRT. These are driftscans of Cassiopeia A to make a radio plot. Several driftscans are made last week and combined. Always nice to see whats possible with a 1.5-1.9 meter dish. 2 LNA's and a bandpass filter, connected to a RTL-SDR at 1424 MHz. Happy that I got Cygnus complex and now Cassiopeia A which is the second radio source which is possible to receive with this dish.