Category: Airspy

SDR# 1717 Officially Released: Dark Mode and Other Skins now Available

Release 1717 of the popular SDR# software that is commonly used with RTL-SDR dongles has just officially been released (actually already up to r1722 at the time of this post). This release brings with it UI theme customization including a very nice looking dark mode. Over on the Airspy/SDR# groups.io board programmer Youssef wrote:

We are pleased to announce the release of SDR# r1717 with the Telerik User Interface.

This is quite a big jump from the old UI components that will allow us to add many fancy features in the upcoming revisions.
For now, the functionality of the software was ported "one to one" with full support of the existing plugins.
A new Plugin API for the tool bar was added which allows plugin developers to add/remove special buttons for quick access.

Despite a slightly longer loading time at the startup of the application, many performance improvements should be noticed in run time, especially the CPU usage.
The package is now distributed with a set of skins/themes you can select in the control panel under "Display". Later on, we will add custom skins loading capability so you can customize the look and feel of the whole program.

Please note that some themes have slower rendering than others. You will have to experiment until you settle with something that is acceptable for the eye candy and the CPU usage / UI reactivity.

Some older plugins may not support the "Dark" themes and will have some rendering problems. The last unskinned version of SDR# will be still available for download in case you really need it. In any case, plugin developers are invited to support the new skins by either using Telerik UI components or at least setting the display properties of the old components so they render properly.

SDRSharp Dark Theme
SDRSharp Dark Theme

Leif Continues his Comparisons of the Airspy HF+ Discovery, RSP1, Perseus and more SDRs (Parts 3,4,5)

Leif (sm5bsz)'s series comparing the Airspy HF+ Discovery against various other SDRs such as the Perseus, SDRplay RSP1, Airpsy HF+ Dual, Airspy + SpyVerter and AFEDRI SDR-Net continues again, with parts 3, 4, and 5 now having been uploaded to YouTube. In previous posts we covered parts 1 and 2.

The comparisons are very technically inclined, so may be difficult to follow for those unfamiliar with radio theory. We have highlighted the time stamps where he discusses the results.

In conclusion, for all tests the Perseus always comes out on top, with the HF+ Discovery coming a close second. Generally third best is the HF+ Dual, then the AFEDRI, followed by the Airspy+SpyVerter and RSP1.

Part 3: Here performance with real antenna signals is compared. Attenuators are used to make the noise figure 26 dB of all radios at the output of the 7 port resistive splitter. This video is for dynamic range on 7.2 MHz.

Results @ 30:20

Part 4: Here performance with real antenna signals is compared. Attenuators are used to make the noise figure 27 dB of all radios at the output of the 7 port resistive splitter. This video is for dynamic range on 14 MHz.

Results @ 16:04

Part 5: Here here second order intermodulation is studied.

Results @ 13:07

Building An Open Source SDR Based Hydrogen Line Radio Telescope

Over on Reddit we've seen a post by u/ArtichokeHeartAttack who has been working on a hydrogen line radio telescope, based on an RTL-SDR dongle and horn antenna designs by the DSPIRA program, and the Open Source Radio Telescopes website (site appears to be down, linked to the archive.org copy). [u/ArtichokeHeartAttack] has documented their radio telescope building journey, providing a comprehensive top-level document that is able to point interested people in the right direction towards understanding and building their own Hydrogen line radio telescope.

Briefly, their build consists of a horn antenna and reflector designed for the 1,420.4 MHz Hydrogen line frequency. The horn is built out of a few pieces of lumbar, metallic house wall insulation sheets and aluminum tape. The feed is made from a tin can and piece of wire. In terms of radio hardware, they used an Airspy SDR, GPIO labs Hydrogen Line Filter + LNA, and 2x Uputronics Wide band preamps, and a Minicircuits VBF-1445+ filter. For software processing, they used a GNU Radio flowgraph to integrate and record the spectrum.

The results show that they were able to achieve a good hydrogen line peak detection, and they were able to measure the galactic rotation curve doppler shift, and tangent points which prove that we do in fact live in a spiral galaxy.

The Finished Hydrogen Line SDR Based Horn Radio Telescope Antenna
The Finished Hydrogen Line SDR Based Horn Radio Telescope Antenna

Leif Continues his Comparisons of the Airspy HF+ Discovery, RSP1, Perseus and More SDRs

Leif (SM5BSZ) is fairly well known in the SDR community for doing very indepth technical tests of various SDR receivers over on his YouTube channel. Recently he's released part two of a series where he compares the new Airspy HF+ Discovery against various other SDRs such as the Perseus, SDRplay RSP1, Airpsy HF+ Dual, Airspy + SpyVerter and AFEDRI SDR-Net. In the first video he studied the blocking and second order intermodulation effects of each SDR using signal generators. We summarized those results in this previous post.

In the new video Leif compares the dynamic range of each SDR using real HF antenna signals at 7.2 MHz. In order to create a fair test of dynamic range, appropriate attenuation is added to each receiver in order to make their noise figures equivalent, so that the incoming signal strength is the same for each SDR.

The first set of dynamic range results is summarized at time 08:14, and these results show the dynamic range comparisons for strong night time signals. Again like in the other videos the Perseus is used as the reference SDR since it is always the best. The tests show that the HF+ Discovery trails behind the Perseus by only -3dB, followed by the HF+ Dual at -10dB, AFEDRI at -15dB, Airspy+SpyVerter at -18dB and finally the RSP1 at -23dB.

The second set of results is summarized at 17:47 and this includes a day time dynamic range test. The rankings are very similar to the night time test.

Hacking Iridium Satellites With Iridium Toolkit

Over on YouTube TechMinds has uploaded a video showing how to use the Iridium Toolkit software to receive data and audio from Iridium satellites with an Airspy. Iridium is a global satellite service that provides various services such as global paging, satellite phones, tracking and fleet management services, as well as services for emergency, aircraft, maritime and covert operations too. It consists of multiple low earth orbit satellites where there is at least one visible in the sky at any point in time, at most locations on the Earth.

The frequencies used by the older generation Iridium satellites are in the L-band, and the data is completely unencrypted. That allows anyone with an RTL-SDR or other SDR radio to decode the data with the open source Iridium Toolkit. If you're interested in how Iridium Toolkit was developed, see this previous post about Stefan "Sec" Zehl and Schneider's 2016 talk.

In the video Tech Minds shows decoding of various data, including an audio call and the satellite tracks and heat map of Iridium satellites.

Hacking Iridium Satellites With Iridium Toolkit

Testing for Spurious Signals on the Airspy HF+ Discovery

Thank you to Nils Schiffhauer (DK8OK) for submitting an article documenting his tests on the Airspy HF+ Discovery (pdf mirror). Spurred on by discussions on the SDR-Console mailing list, Nils went looking for issues with spurious signals generated by the HF+ itself. In the end he finds some minor spurious signals, but notes that they have absolutely no adverse effects once an antenna is connected.

Youssef Touil (developer of the Airspy HF+ line of products) has also noted that the minimum discernible signal (MDS) of the HF+ is so low that it's become normal for very weak spurs to now be visible without an antenna connected. However, once an antenna is connected the natural atmospheric noise floor which is much higher than the MDS hides these spurs, and so the spurs have no consequence on reception.

In Nils' first test he uses a very high end Winradio W65DDC SDR to detect the spurs coming from an Airspy HF+, Airspy HF+ with preselector retrofit, and the Airspy HF+ Discovery. The results are quoted below:

[With the Airspy HF+] you indeed see a very few spurious signals, all well below -140 dBm/Hz.

With the Airspy HF+ Preselector connected, the number of spurious signal is very much reduced, as is their maximum level.

This picture still further improves with the Airspy HF+ Discovery connected: all visible seven spurious signals are measured to well below -150 dBm/Hz.

The first result is clear:

  • Airspy has improved also the spurious signals from model to model, landing at a stunning
    reduction with their matchbox-like Discovery.
  • The spurious signals were significantly reduced in both numbers and level.
  • Together with sensitivity and dynamic range, the performance of these SDRs is exceptionally
    good. If you see their price tag, they are a real bargain.
  • Overall: they deliver professional performance in every important aspect at an incredible low
    price.

In the second test Nils tunes to the center of a spur, then tested with a dummy load and then antenna connected. His results showed that all spurs disappeared once an antenna was connected. He summarizes below:

Yes, there are a very few and low-level spurious signals at all Airspy’s receivers – as they are found [much] worse at some competing SDRs.

  • By development, even this has been significantly improved from model to model with the new Discovery leading the gang.
  • All spurious signals disappear with an antenna connected.
  • There has been found no case where, in practice, any spurious signal even remotely touched or even limited reception of the most miniscule signals.To complain about “spurious signals” simply is “Much Ado about Nothing” in an Ivory Tower, far away from any practical application.
Nils also tested 7300 kHz reception and the co-existance of weak amateur radio signals with strong broadcast signals.
Nils also tested 7300 kHz reception and the co-existance of weak amateur radio signals with strong broadcast signals.

Decoding PAL Video from a Nintendo with An Airspy SDR Part 2

Oona combines composite output for color images.
Oona combines composite output for color images.

Last week we posted about Oona Räisänen's ([Windytan] and @windyoona) project to capture live video from her 1985 Nintendo Entertainment System (NES) using an Airspy SDR. In order to avoid expensive Video Capture cards which didn't work on her Mac, she used an Airspy SDR to decode the PAL composite video output of the NES. Last week she had black and white video working.

This week she has full color working, and has on her blog posted a write up about her project with the Airspy and her experiences with trying to find a suitable capture solution. She also goes into some detail about the CPU performance considerations of this solution, noting that there are some performance bottlenecks. She's also uploaded a video showing the results in action.

MacBook decodes PAL video via SDR

Airspy HF+ Discovery: Collection of Tests and Reviews

The Airspy HF+ Discovery is a new US$169 software defined radio that recently began shipping. On HF it can tune from 0.5 kHz to 31 MHz, and on VHF from 60 to 260 MHz.

It is advertised as having extremely high dynamic range and sensitivity, comparable to high end (and much more expensive) SDRs. High dynamic range means that extremely strong powerhouse stations will not block weaker stations from being received. On lower end SDRs strong stations can cause an SDR to overload, resulting in poor reception.

The HF+ Discovery is an improvement over the original HF+ (now known as the HF+ Dual Port). Back in 2017 we reviewed the original HF+ and found it's performance to be excellent. However, a number of people found that by using low loss preselectors the performance could improve the performance even further.

Originally Youssef (the developer of Airspy products) began designing a low cost preselector add on for the HF+ Dual Port, in order to increase the already great dynamic range. However, it was deemed too difficult for users to retrofit their devices. The result was the creation of the HF+ Discovery, which combines these preselectors with the already excellent HF+ SDR circuitry. Compared to the HF+ Dual, the Discovery is much smaller, and comes in a plastic case rather than a metal one. Instead of the split HF/VHF dual ports seen on the HF+ Dual, the Discovery only has one port that covers both bands. Overall performance with the preselectors is increased, and the price is even lower than the HF+ Dual Port.

Over the past few weeks a number of reviews and comparison videos have come out. Below we list a few that we found interesting.

In this video, the Techminds YouTube channel gives an overview on what the HF+ discovery is, and then gives a quick demo. If you haven't heard of the HF+ Discovery before then this is a good introduction.

Airspy HF+ Discovery - Overview & Brief Testing

The following video by Leif (sm5bsz) is the most technical, as he performs sensitivity and  dynamic range lab tests on multiple SDRs including the Microtelecom Perseus, Airspy HF+ Dual Port, Airspy HF+ Discovery, Airspy Spyverter plus Airspy, SDRplay RSP1 and AFEDRI SDR-Net.

If you want to skip the testing procedures, a summary of the results are presented at 16:20,  31:06, 38:19, and 53:55 video time. In most tests the HF+ Discovery is the second best, after the Perseus.

The first in a series of videos that compare the dynamic range of six receivers: Microtelecom Perseus, Airspy HF+ Dual Port,, Airspy HF+ Discovery, Airspy Spyverter plus Airspy, SDRplay RSP1 and AFEDRI SDR-Net. Here blocking and second order intermodulation is studied with signal generators. Attenuators are used to make the noise figure 26 dB of all radios at the output of the 6 port Wilkingson splitter. This video is for dynamic range on 7.2 MHz. The Discovery is a pre-production unit and the noise figure is a little higher than that of regular production units for unknown reasons.

In this article over on the SWLing Blog guest poster Guy Atkins submits a comparison video between the Airspy HF+ Discovery and an Elad FDM-DUOr ($899). Results appear to show that the HF+ has close to identical performance.

Over on YouTube icholakov has posted two comparison videos. In the first he compares the HF+ Discovery to the HF+ Original. In the second video he compares the HF+ Discovery against an SDRplay RSP1A.

Airspy HF+ Discovery SDR vs. HF+ Original SDR - Blind Test

Airspy HF+ Discovery vs. SDRPlay RSP-1A on Medum Wave and Short Wave

We've posted about this review before, but it's still one of the best. Here Fenu-Radio compares the HF+ Discovery against a very expensive Winradio G33DDC and posts multiple comparison audio files. He concludes that the HF+ Discovery compares favorably to the WinRadio.

In this post, Arctic DX measures the sensitivty of the HF+ Discovery, providing a very useful sensitivity comparison table against multiple other SDRs. The HF+ Discovery comes in with excellent numbers.

Over on Twitter there has been a lot of activity too. In the following Tweet, Simon Brown, author of the popular SDR-Console V3 application notes that the HF+ Discovery is virtually immune to strong signals.

We've also seen how the HF+ Discovery's LF performance is so good that it's possible to simply connect a photodiode and see the light spectrum produced by CFLs.