Over on YouTube Tech Minds has posted a video of him using an Airspy HF+ Discovery to hunt for signals like non-direction beacons (NDB's) and other morse code CW beacons. The Airspy HF+ Discovery is a new software defined radio that builds upon the already excellent original Airspy HF+.
One key improvement that many people have been experimenting with is it's improved VLF and LF capabilities, which is where most beacons are. It is capable of tuning down to 0.5 kHz (500 Hz). Over on Twitter, @prog (creator of these Airspy products) has been experimenting with simple and small ferrite loop antennas for VLF/LF and finding excellent results due to the low noise figure and good impedance matching of the HF+ Discovery.
Hunting LF/MF/HF Beacons With An Airspy HF+ Discovery
You may recall that a few years ago we released a tutorial on how to set up and use [SDRTrunk]. Fast forward a few years and the software has seen numerous changes. This application was designed primarily for tracking trunking radio systems but also has the ability to decode things like MDC-1200, LoJack and more.
The software is compatible with many Software Defined Radios such as our RTL-SDR v3, HackRF and the Airspy. Some of the newer improvements include a bundled copy of java so that an installation of java is not required on the host computer, as well as decoding improvements for P25 among other digital voice modes. You can find a full list of improvements along with the latest release on [GitHub]
The biggest feature many have been waiting for is the ability to import talk groups for their radio system into the application from radio reference. While this has not yet been implemented, user [Twilliamson3] has created a [web application] that will convert table data from radio reference into a format that is supported by SDRTrunk.
The Airspy HF+ Discovery is a smaller, lighter and improved version of the Airspy HF+ which is an HF and VHF SDR with very high dynamic range. The Discovery builds on the HF+ by adding low loss preselectors. This increases the dynamic range even further, and allows the Discovery to compete with some very high end (and much more expensive) SDRs.
Currently the Airspy HF+ Discovery is available for preorder for USD$169. There have been a few delays in getting the unit out, but it appears that the Airspy team will begin shipping very soon.
In the review Fenu-Radio compares the Discovery against the G33DDC and finds absolutely no difference in performance between the two. In the review he's also uploaded several audio comparison samples so that you can hear for yourself how identical the two radios are.
Over on GitHub Ian Wraith has released his design and microcontroller code for a low cost 2.4 GHz downconverter circuit. A downconverter is a hardware device that shifts the signals that it receives into a lower frequency band. This is useful in the case of RTL-SDRs and Airspy SDRs, as their maximum frequency range is only 1.7 GHz. Ian's 2.4 GHz downconverter reduces those 2.4 GHz signals down to 1 GHz, which can then be received with his Airspy.
Rather than designing a circuit from scratch, Ian's design makes use of several very cheap Chinese evaluation/development boards that he found on eBay. It costs of a mixer board, oscillator board, and an STM32 development board for controlling the oscillator board via SPI. The whole set of hardware cost him less than £30 (~37 USD).
After spending some time working through the difficulties in programming the SPI interface on the STM32 board, he was able to get the downconverter circuit fully working. He notes that he's been able to receive WiFi, Zigbee, Bluetooth and ISM band signals at 2.4 GHz, as well as 3G and 4G cellular signals at 2.6 GHz.
Ian Wraith's Downconverter consisting of three off the shelf cheap Chinese eBay boards.
This week on the SignalsEverywhere YouTube channel, host Corrosive gives us a tutorial on common modulations that you'll see on your software defined radio. His tutorial covers Amplitude Modulation (AM), Frequency Modulation (FM), Single Side Band (SSB) and Conintuous Wave (CW) modulations. In the video he shows what they look like and how to select the correct mode and bandwidth settings in SDR#. Corrosive uses an Airspy in the video, but the same concepts are valid for any SDR, like the RTL-SDR.
If you're new to SDR then this is a great introductory video to watch and learn from.
AM FM SSB and CW | Common Modulation You'll See on SDR
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
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.Drone used in the experiment
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
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.
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+
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.
Over on YouTube Tech Minds has posted a video of him using an Airspy HF+ Discovery to hunt for signals like non-direction beacons (NDB's) and other morse code CW beacons. The Airspy HF+ Discovery is a new software defined radio that builds upon the already excellent original Airspy HF+.
One key improvement that many people have been experimenting with is it's improved VLF and LF capabilities, which is where most beacons are. It is capable of tuning down to 0.5 kHz (500 Hz). Over on Twitter, @prog (creator of these Airspy products) has been experimenting with simple and small ferrite loop antennas for VLF/LF and finding excellent results due to the low noise figure and good impedance matching of the HF+ Discovery.
Hunting LF/MF/HF Beacons With An Airspy HF+ Discovery
You may recall that a few years ago we released a tutorial on how to set up and use [SDRTrunk]. Fast forward a few years and the software has seen numerous changes. This application was designed primarily for tracking trunking radio systems but also has the ability to decode things like MDC-1200, LoJack and more.
The software is compatible with many Software Defined Radios such as our RTL-SDR v3, HackRF and the Airspy. Some of the newer improvements include a bundled copy of java so that an installation of java is not required on the host computer, as well as decoding improvements for P25 among other digital voice modes. You can find a full list of improvements along with the latest release on [GitHub]
The biggest feature many have been waiting for is the ability to import talk groups for their radio system into the application from radio reference. While this has not yet been implemented, user [Twilliamson3] has created a [web application] that will convert table data from radio reference into a format that is supported by SDRTrunk.
The Airspy HF+ Discovery is a smaller, lighter and improved version of the Airspy HF+ which is an HF and VHF SDR with very high dynamic range. The Discovery builds on the HF+ by adding low loss preselectors. This increases the dynamic range even further, and allows the Discovery to compete with some very high end (and much more expensive) SDRs.
Currently the Airspy HF+ Discovery is available for preorder for USD$169. There have been a few delays in getting the unit out, but it appears that the Airspy team will begin shipping very soon.
In the review Fenu-Radio compares the Discovery against the G33DDC and finds absolutely no difference in performance between the two. In the review he's also uploaded several audio comparison samples so that you can hear for yourself how identical the two radios are.
Over on GitHub Ian Wraith has released his design and microcontroller code for a low cost 2.4 GHz downconverter circuit. A downconverter is a hardware device that shifts the signals that it receives into a lower frequency band. This is useful in the case of RTL-SDRs and Airspy SDRs, as their maximum frequency range is only 1.7 GHz. Ian's 2.4 GHz downconverter reduces those 2.4 GHz signals down to 1 GHz, which can then be received with his Airspy.
Rather than designing a circuit from scratch, Ian's design makes use of several very cheap Chinese evaluation/development boards that he found on eBay. It costs of a mixer board, oscillator board, and an STM32 development board for controlling the oscillator board via SPI. The whole set of hardware cost him less than £30 (~37 USD).
After spending some time working through the difficulties in programming the SPI interface on the STM32 board, he was able to get the downconverter circuit fully working. He notes that he's been able to receive WiFi, Zigbee, Bluetooth and ISM band signals at 2.4 GHz, as well as 3G and 4G cellular signals at 2.6 GHz.
Ian Wraith's Downconverter consisting of three off the shelf cheap Chinese eBay boards.
This week on the SignalsEverywhere YouTube channel, host Corrosive gives us a tutorial on common modulations that you'll see on your software defined radio. His tutorial covers Amplitude Modulation (AM), Frequency Modulation (FM), Single Side Band (SSB) and Conintuous Wave (CW) modulations. In the video he shows what they look like and how to select the correct mode and bandwidth settings in SDR#. Corrosive uses an Airspy in the video, but the same concepts are valid for any SDR, like the RTL-SDR.
If you're new to SDR then this is a great introductory video to watch and learn from.
AM FM SSB and CW | Common Modulation You'll See on SDR
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
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.Drone used in the experiment
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
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.
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+
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.
