Tagged: airspy

SignalsEverywhere: What SDR To Buy? Choose the Right one For You

Over on his YouTube channel SignalsEverywhere, Corrosive has just released a new video titled "Software Defined Radio Introduction | What SDR To Buy? | Choose the Right one For You". The video is an introduction to low cost software defined radios and could be useful if you're wondering which SDR you should purchase.

The video includes a brief overview of the Airspy, KerberosSDR, PlutoSDR, LimeSDR Mini, HackRF, SDRplay RSPduo and various RTL-SDR dongles. In addition to the hardware itself Corrosive also discusses the compatible software available for each SDR.

Software Defined Radio Introduction | What SDR To Buy? | Choose the Right one For You

Tracking Tagged Orangutans in the Bornean Jungle with Drones, GNU Radio and an Airspy Mini

Due to various human activities causing the environmental destruction of it's habitat, the Orangutan is now classed as a critically endangered species. In addition to being endangered, Orangutans face another problem in that they are often captured and sold as pets due to their intelligence and cuteness.

To combat these problems, NGOs, charities and rescue centers have been using RF tags on rehabilitated Orangutans that have released back into the wild. The RF tag regularly transmits a data-less pulse at VHF frequencies which is then typically tracked using direction finding equipment such as a directional Yagi antenna. The range is only approximately 200-400m. 

In order to try and alleviate the range issue Dirk Gorissen has been working on creating a drone based system that could detect the VHF transmission and create a heatmap of Orangutan positions. The first iteration of his system uses an RTL-SDR, Odroid and lightweight loop antenna. A simple Python script then monitors the spectrum and logs the drones current location, altitude, speed and heading when a pulse is detected. Tests confirmed that the signal was able to be detected from the sky, but unfortunately the drone was eventually crashed and lost before it could be properly used.

In his second try a few years later, Dirk used a larger drone and switched SDRs to an Airspy Mini with preamp. The pulse detection code was also improved by using GNU Radio to create a DSP algorithm combining peak detection, cross correlation with a known template of the signal, and a phase locked loop. Visualization and data transfer is achieved through react.js and a Flask web server running on the drones WiFi hotspot. This time with the new drone and system Dirk was able to successfully detect and locate several Orangutan's on various flights, despite noting that some RF tags appeared to be glitchy.

Orangutan Detected with Drone, Airspy Mini and GNU Radio.
Orangutan Detected with Drone, Airspy Mini and GNU Radio.
Drone used in the experiment
Drone used in the experiment

Airspy HF+ Discovery Now Available for Preorder + Brief Initial Review

The Airspy team have recently announced the release of their new "Airspy HF+ Discovery". The Discovery is a smaller, lighter and improved version of the Airspy HF+. The frequency range, bandwidth and bit depth and specs all remain the same, but there are some improvements to the dynamic range due to the addition of preselectors. The original Airspy HF+ was released back in mid-2017 and it still is in our opinion one of the best low cost HF DX SDRs because of its very high dynamic range design, so strong interfering signals are not much of a problem. We have a previous review of the Airspy HF+ available here were we compare it against a number of other HF SDRs.

Although the dynamic range was very high, some users reported that extremely strong signals could still desensitize the HF+. So in response the new HF+ Discovery improves on the dynamic range even further by including multiple low insertion loss preselectors built in to the front end. For HF there is are 0, 5, 10 or 17 MHz High Pass Filter corners, and 5 or 31 MHz Low Pass filter corners in series which can provide filtering for a number of bands. For VHF, there are 60-118 MHz and 118-260 MHz filters. The designer boasts that the inclusion of these filters bring the HF+ Discovery up to the performance level of expensive new SDR based ham rigs like the Icom 7300.

Airspy HF+ Discovery Block Diagram
Airspy HF+ Discovery Block Diagram

As for the physical design, the enclosure is now much smaller (60 x 45 x 10 mm) and made from plastic. These changes make the SDR very light at only 28 grams (1 oz). Although the case is plastic, local interference doesn't seem to be an issue as the PCB itself is fully shielded. The plastic case is rugged and will withstand a beating. Also, the original HF+ had two input ports, one for HF and one for VHF whereas the HF+ Discovery only has one input port which covers all bands.

Despite the improvements and additional circuitry, the Airspy HF+ Discovery is actually priced cheaper than the original. The original HF+ costs US$199, but the Discovery is only US$169. So unless you require the two input ports, the HF+ Discovery should be the way to go. Currently the HF+ Discovery is in preorder status, and can be ordered internationally from the manufacturer iTead, or within the US from airspy.us. As far as we can see no expected shipping date has been given yet, but we expect that it would ship soon.

airspy_discovery_1
airspy_discovery_3
airspy_discovery_2
airspy_discovery_4
RTL-SDR For Scale

RTL-SDR For Scale

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Initial Testing

We were sent a prototype sample of the Airspy Discovery HF+ a few weeks ago. We note that the version we received was an early prototype and does not yet implement the 10 MHz and 17 MHz HF filters.

From our test on real world signals we find that it performs at least as good as the original Airspy HF+, if not better due to the additional filtering. The signals in our area were not strong enough to really overload the original Airspy HF+, so any benefit from the additional filtering may not be too apparent.  Insertion loss from the filters seems to be not noticeable, as we saw no differences to SNR levels between the two units.

In our VHF tests we saw no differences between the two units, but as with HF we note that it would take some fairly strong signals to make a difference.

In a future post we'll follow up with some tests by injecting strong signals into the SDR, and seeing how well it can performs with the additional filtering compared to the original.

TOP: Airspy HF+ Discovery, BOTTOM: Original Airspy HF+
TOP: Airspy HF+ Discovery, BOTTOM: Original Airspy HF+

Conclusion

If you have an HF+ and were still troubled by really strong out of band interferers, the HF+ Discovery might be a good upgrade. Newcomers to SDR looking for high a performance DX SDR for HF and VHF should also strongly consider the HF+ Discovery. The original HF+ is still one of the best low cost DX SDRs we've tested, and the Discovery only makes it better.

As far as we can see regarding the choice between the original HF+ and HF+ Discovery, the only reason to really consider the original HF+ would be if you prefer to have separate HF and VHF antenna ports. The plastic case brings no real disadvantage, and the preselectors improve dynamic range and have no noticeable insertion loss.

SignalsEverywhere: What SDR To Buy? Choose the Right one For You

Over on his YouTube channel SignalsEverywhere, Corrosive has just released a new video titled "Software Defined Radio Introduction | What SDR To Buy? | Choose the Right one For You". The video is an introduction to low cost software defined radios and could be useful if you're wondering which SDR you should purchase.

The video includes a brief overview of the Airspy, KerberosSDR, PlutoSDR, LimeSDR Mini, HackRF, SDRplay RSPduo and various RTL-SDR dongles. In addition to the hardware itself Corrosive also discusses the compatible software available for each SDR.

Software Defined Radio Introduction | What SDR To Buy? | Choose the Right one For You

Tracking Tagged Orangutans in the Bornean Jungle with Drones, GNU Radio and an Airspy Mini

Due to various human activities causing the environmental destruction of it's habitat, the Orangutan is now classed as a critically endangered species. In addition to being endangered, Orangutans face another problem in that they are often captured and sold as pets due to their intelligence and cuteness.

To combat these problems, NGOs, charities and rescue centers have been using RF tags on rehabilitated Orangutans that have released back into the wild. The RF tag regularly transmits a data-less pulse at VHF frequencies which is then typically tracked using direction finding equipment such as a directional Yagi antenna. The range is only approximately 200-400m. 

In order to try and alleviate the range issue Dirk Gorissen has been working on creating a drone based system that could detect the VHF transmission and create a heatmap of Orangutan positions. The first iteration of his system uses an RTL-SDR, Odroid and lightweight loop antenna. A simple Python script then monitors the spectrum and logs the drones current location, altitude, speed and heading when a pulse is detected. Tests confirmed that the signal was able to be detected from the sky, but unfortunately the drone was eventually crashed and lost before it could be properly used.

In his second try a few years later, Dirk used a larger drone and switched SDRs to an Airspy Mini with preamp. The pulse detection code was also improved by using GNU Radio to create a DSP algorithm combining peak detection, cross correlation with a known template of the signal, and a phase locked loop. Visualization and data transfer is achieved through react.js and a Flask web server running on the drones WiFi hotspot. This time with the new drone and system Dirk was able to successfully detect and locate several Orangutan's on various flights, despite noting that some RF tags appeared to be glitchy.

Orangutan Detected with Drone, Airspy Mini and GNU Radio.
Orangutan Detected with Drone, Airspy Mini and GNU Radio.
Drone used in the experiment
Drone used in the experiment

Airspy HF+ Discovery Now Available for Preorder + Brief Initial Review

The Airspy team have recently announced the release of their new "Airspy HF+ Discovery". The Discovery is a smaller, lighter and improved version of the Airspy HF+. The frequency range, bandwidth and bit depth and specs all remain the same, but there are some improvements to the dynamic range due to the addition of preselectors. The original Airspy HF+ was released back in mid-2017 and it still is in our opinion one of the best low cost HF DX SDRs because of its very high dynamic range design, so strong interfering signals are not much of a problem. We have a previous review of the Airspy HF+ available here were we compare it against a number of other HF SDRs.

Although the dynamic range was very high, some users reported that extremely strong signals could still desensitize the HF+. So in response the new HF+ Discovery improves on the dynamic range even further by including multiple low insertion loss preselectors built in to the front end. For HF there is are 0, 5, 10 or 17 MHz High Pass Filter corners, and 5 or 31 MHz Low Pass filter corners in series which can provide filtering for a number of bands. For VHF, there are 60-118 MHz and 118-260 MHz filters. The designer boasts that the inclusion of these filters bring the HF+ Discovery up to the performance level of expensive new SDR based ham rigs like the Icom 7300.

Airspy HF+ Discovery Block Diagram
Airspy HF+ Discovery Block Diagram

As for the physical design, the enclosure is now much smaller (60 x 45 x 10 mm) and made from plastic. These changes make the SDR very light at only 28 grams (1 oz). Although the case is plastic, local interference doesn't seem to be an issue as the PCB itself is fully shielded. The plastic case is rugged and will withstand a beating. Also, the original HF+ had two input ports, one for HF and one for VHF whereas the HF+ Discovery only has one input port which covers all bands.

Despite the improvements and additional circuitry, the Airspy HF+ Discovery is actually priced cheaper than the original. The original HF+ costs US$199, but the Discovery is only US$169. So unless you require the two input ports, the HF+ Discovery should be the way to go. Currently the HF+ Discovery is in preorder status, and can be ordered internationally from the manufacturer iTead, or within the US from airspy.us. As far as we can see no expected shipping date has been given yet, but we expect that it would ship soon.

airspy_discovery_1
airspy_discovery_3
airspy_discovery_2
airspy_discovery_4
RTL-SDR For Scale

RTL-SDR For Scale

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Initial Testing

We were sent a prototype sample of the Airspy Discovery HF+ a few weeks ago. We note that the version we received was an early prototype and does not yet implement the 10 MHz and 17 MHz HF filters.

From our test on real world signals we find that it performs at least as good as the original Airspy HF+, if not better due to the additional filtering. The signals in our area were not strong enough to really overload the original Airspy HF+, so any benefit from the additional filtering may not be too apparent.  Insertion loss from the filters seems to be not noticeable, as we saw no differences to SNR levels between the two units.

In our VHF tests we saw no differences between the two units, but as with HF we note that it would take some fairly strong signals to make a difference.

In a future post we'll follow up with some tests by injecting strong signals into the SDR, and seeing how well it can performs with the additional filtering compared to the original.

TOP: Airspy HF+ Discovery, BOTTOM: Original Airspy HF+
TOP: Airspy HF+ Discovery, BOTTOM: Original Airspy HF+

Conclusion

If you have an HF+ and were still troubled by really strong out of band interferers, the HF+ Discovery might be a good upgrade. Newcomers to SDR looking for high a performance DX SDR for HF and VHF should also strongly consider the HF+ Discovery. The original HF+ is still one of the best low cost DX SDRs we've tested, and the Discovery only makes it better.

As far as we can see regarding the choice between the original HF+ and HF+ Discovery, the only reason to really consider the original HF+ would be if you prefer to have separate HF and VHF antenna ports. The plastic case brings no real disadvantage, and the preselectors improve dynamic range and have no noticeable insertion loss.

Weather Satellite Images from Geostationary COMS-1 Received

COMS-1 Geostationary Satellite Footprint
COMS-1 Geostationary Satellite Footprint https://www.wmo-sat.info/oscar/Satellites/view/33

COMS-1 is a geostationary weather satellited operated by the Korean Meteorological Agency (KMA) which was launched back in 2010. It is similar to NOAA GOES satellites as it is also geostationary orbit (@128.2°E - footprint covers all of Asia + AUS/NZ), and so is far away enough to image the entire disk of the Earth at once. Unfortunately, unlike the GOES satellites which have in the past few years become relatively easy for hobbyists to decode, the COMS-1 LRIT and HRIT downlink data is encrypted by KMA. KMA only appear to provide decryption keys to governments, research institutes and large organizations upon request.

However, recently Australian @sam210723 was able to successfully create code to decrypt the key message file and obtain the images. From a previous Twitter post of his, it appears that the encryption keys from the KMA example code are actually valid and can be used without needing to apply for a key.

Sam notes that he'll soon release a full blog post on his results, but for now he has an older post from last year that explains a bit about the satellite and decryption of the LRIT Key. His code is available on GitHub, and in a recent Twitter post he shows some example images that he's been able to receive using an Airspy SDR.

Receiving Voice Communications From the Soyuz MS-12 Expedition to the ISS

On March 14 the Soyuz MS-12 spacecraft mission was launched and this carried three astronauts to the International Space Station (ISS). Back on the ground, YouTube creator Tysonpower was able to receive the voice communications of Russian cosmonaut Alexey Ovchinin while the Soyuz spacecraft was approaching the ISS. To do this he used an Airspy SDR and home made QFH antenna, and he notes that reception could just have easily been achieved with an RTL-SDR.

Tysonpower has uploaded a video explaining what he received along with a subtitled and translated recording of the communication. More information also available on his blog post.

[EN subs] Empfang von Cosmonaut Alexey Ovchinin im Soyuz MS-12

Reducing HF Electrical Noise by Using a Faraday Cage for Switch-Mode Power Supplies

Over on his blog, DXer OH2-2192 was frustrated by lots of local electrical noise showing up on the HF bands on his Airspy + Spyverter SDR receiver. He discovered that the majority of the noise he was seeing was coming from the switch mode power supplies that power the electronic devices used in his setup. Switch mode power supplies are very common in the modern world, with almost every electronic device using one to efficiently convert wall AC into DC power. However, they convert power by rapidly switching on and off, and these on/off square wave pulses cause a lot of RF noise especially on the HF spectrum.

Instead of changing to noise free linear regulators which are expensive, very heavy and big, OH2-2192 decided that he'd try creating a Faraday cage shield out of metal mesh to enclose all his switch-mode power supplies. Using a simple AM loop antenna and Airspy's Spectrum Spy software he measured the amount of noise produced by a switch-mode supply placed inside and outside of the cage. The results he saw were very promising with the shielded supply eliminating the noise almost entirely.

Faraday Cage Shield for Switch Mode Power Supplies
Faraday Cage Shield for Switch Mode Power Supplies (Right image shows the results of a switching supply placed outside and inside the Faraday cage)

Using an Airspy HF+ with SDR# and WSJT-X to Decode FT8 + SpyServer FT8 Decoding Demo

Over on YouTube user TheGazLab has uploaded a video that reviews the Airspy HF+, and also shows how to use the HF+ with SDR# and WSJT-X in order to create a FT8 monitor. The Airspy HF+ is high dynamic range HF/VHF receiver designed for DXing.

In the video TheGazLab demonstrates to us the decoding in real time, and explains the CAT control SDR# plugin that he's using. The CAT control plugin when combined with a virtual serial port driver allows the WSJT-X program to automatically tune SDR# to the FT8 frequency selected in WSJT-X.

Later in the video he also discusses the SpyServer network which allows SDR# users to connect to remote public Airspy and RTL-SDR units over the internet. He demonstrates connecting to a public server in the UK, and decoding FT8 via the remote server. The video also shows the new SpyServer interface by  which nicely lays out the world SpyServer network on a map, making it easy to choose a desired location to listen to.

Airspy HFPlus, SDR# and WSJT-X with full CAT control decoding FT-8

moRFeusQT Updates: Automatic Tracking Generator Plotting with Airspy

Outernet's moRFeus is a signal generator and frequency mixer that can be controlled either by it's built in LCD screen, or via software on a Windows or Linux PC. It can generate a clean low phase noise tone anywhere between 85 to 5400 MHz. Because it can be computer controlled it is possible to use moRFeus as a tracking generator for characterizing filters and measuring antenna SWR. A tracking generator is just a signal generator that can be set to output at the same frequency that the measurement receiver is tuned to.

In the past we've posted about some software developed by Ohan Smit, which allows a moRFeus to be controlled on a Windows/Linux PC via a nice GUI. Recently he's updated the software and it can now draw power (dbFS) graphs for characterizing filters when combined with an Airspy and TCP comms to GQRX. Ohan writes:

So when you press sweep, it detects if there is any TCP servers on port 7356 and if so tunes the radio and gets a power measurement and after the sweep is done, morfeusqt renders a graph on the fly.

It now also supports multiple devices, no configurations required. It just opens another window for the second device.

These features thus far work on both Windows 10 and Ubuntu 18.04.1, these are my two testing environments with GQRX and the Airspy.

Ohan also notes that he's working on several new features such as the ability to plot VSWR, remote control of the moRFeus via TCP, support for multiple SDR TCP protocols such as rtl_tcp, soapytcp etc, threading and progress bars, as well as possibly support for cheap Osmo-FL2K devices as a tracking generator.

You can follow his developments live on the Outernet forums.

moRFeus used as a tracking generator with an Airspy with the morfeusQT software
moRFeus used as a tracking generator with an Airspy with the morfeusQT software