Tagged: airspy hf+ discovery

New Magazine Reviews of the Airspy HF+ Discovery

Recently three new reviews of the Airspy HF+ Discovery have come out in various radio  enthusiast magazines from around the world. All three reviews have been released for free in PDF form over on the Airspy reviews page. Unsurprisingly each review praises the HF+ Discovery as it's clearly a great radio.

The first review comes from the September Edition of "The Spectrum Monitor" and is written by Larry Van Horn (N5FPW).

” Most the low-priced SDRs have never been preselected, mostly for cost reasons, and will suffer strong signal overload especially in high RF areas (urban/metro areas). Without exception, these devices usually have major problems with the antennas that radio hobbyist use. They overload very quickly, which makes serious reception on long, medium and shortwaves rather difficult. The HF+ Discovery is the big exception. Based on our testing, the Airspy HF+ Discovery has no equal at its price point. You will find world-class performance and an amazing piece of hardware wrapped up in a package smaller than a matchbox. The Airspy line has a very fine reputation in the radio hobby. In reviews published in Gayle Van Horn’s 2018 Global Radio Guide and the 2019 World Radio TV Handbook, the Airspy HF+ received high marks by the testers and a “Best Value” rating. ”

The second review is by Nils Schiffhauer (DK8OK) which was published in the October 2019 edition of "Radio User". For German readers, Nils also published a similar review written in German for the December edition of "Radio-Kurier".

Just another SDR? Wait, this beast is different – not only in size and price but also in terms of its concept and performance. In common with some former models of AirSpy SDRs, the new AirSpy HF+ Discovery model (henceforth: ‘Discovery’) is a joint venture of Youssef Touil and his team at the Chinese ITEAD studio and ST Microelectronics. This smart team has already developed, for example, the ground-breaking AirSpy HF+, which is widely considered to be the top performer in its class. The Discovery continues this success story.

The Discovery shines with less noise, and, astonishingly, less crackle. In at least 80% of these diffi cult cases, intelligibility with the Discovery is clearly better. With very few stations, this receiver will even make the difference between understanding the identification of a station and not copying it. In August, I also tested the Discovery with the most ‘demanding’ band, the Very Low Frequency range (VLF). Here most SDRs – and certainly the majority of budget SDRs – reach their limits, lacking sensitivity and filling up the band with internally-generated signals. Thanks to a newly developed input section to start at even 500Hz, this receiver shows outstanding strong and clean signals from as far as the US Navy in Australia.

Covers from the Spectrum Monitor and Radio User Airspy HF+ Discovery Reviews
Covers from the Spectrum Monitor and Radio User Airspy HF+ Discovery Reviews

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

rx7compare-part3

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

rx7compare-part4

Part 5: Here here second order intermodulation is studied.

Results @ 13:07

rx7compare part5

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.

rx7compare-part2

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.

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.

rx7compare-part1

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.

AirSpy HF+ Discovery: First Impressions on Medium Wave vs. Elad FDM-DUOr

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.

Using an Airspy HF+ Discovery to Hunt for HF Beacons

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 HF Beacons With An Airspy HF+ Discovery

Fenu Radio Reviews the Airspy HF+ Discovery

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.

Over on his blog, radio product reviewer Fenu-Radio has received an Airspy HF+ Discovery, and has given it an in depth review and put it through several real world tests. Fenu-Radio notes that while the initial prototype unit that he received had some issues with overload above 19 MHz, the latest production version has completely remedied this, resulting in impressive performance that competes favorably with the high end USD$2000 Winradio G33DDC software defined radio.

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.

Fenu-Radio's Airspy HF+ Discovery Review Unit
Fenu-Radio's Airspy HF+ Discovery Review Unit

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.

New Magazine Reviews of the Airspy HF+ Discovery

Recently three new reviews of the Airspy HF+ Discovery have come out in various radio  enthusiast magazines from around the world. All three reviews have been released for free in PDF form over on the Airspy reviews page. Unsurprisingly each review praises the HF+ Discovery as it's clearly a great radio.

The first review comes from the September Edition of "The Spectrum Monitor" and is written by Larry Van Horn (N5FPW).

” Most the low-priced SDRs have never been preselected, mostly for cost reasons, and will suffer strong signal overload especially in high RF areas (urban/metro areas). Without exception, these devices usually have major problems with the antennas that radio hobbyist use. They overload very quickly, which makes serious reception on long, medium and shortwaves rather difficult. The HF+ Discovery is the big exception. Based on our testing, the Airspy HF+ Discovery has no equal at its price point. You will find world-class performance and an amazing piece of hardware wrapped up in a package smaller than a matchbox. The Airspy line has a very fine reputation in the radio hobby. In reviews published in Gayle Van Horn’s 2018 Global Radio Guide and the 2019 World Radio TV Handbook, the Airspy HF+ received high marks by the testers and a “Best Value” rating. ”

The second review is by Nils Schiffhauer (DK8OK) which was published in the October 2019 edition of "Radio User". For German readers, Nils also published a similar review written in German for the December edition of "Radio-Kurier".

Just another SDR? Wait, this beast is different – not only in size and price but also in terms of its concept and performance. In common with some former models of AirSpy SDRs, the new AirSpy HF+ Discovery model (henceforth: ‘Discovery’) is a joint venture of Youssef Touil and his team at the Chinese ITEAD studio and ST Microelectronics. This smart team has already developed, for example, the ground-breaking AirSpy HF+, which is widely considered to be the top performer in its class. The Discovery continues this success story.

The Discovery shines with less noise, and, astonishingly, less crackle. In at least 80% of these diffi cult cases, intelligibility with the Discovery is clearly better. With very few stations, this receiver will even make the difference between understanding the identification of a station and not copying it. In August, I also tested the Discovery with the most ‘demanding’ band, the Very Low Frequency range (VLF). Here most SDRs – and certainly the majority of budget SDRs – reach their limits, lacking sensitivity and filling up the band with internally-generated signals. Thanks to a newly developed input section to start at even 500Hz, this receiver shows outstanding strong and clean signals from as far as the US Navy in Australia.

Covers from the Spectrum Monitor and Radio User Airspy HF+ Discovery Reviews
Covers from the Spectrum Monitor and Radio User Airspy HF+ Discovery Reviews

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

rx7compare-part3

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

rx7compare-part4

Part 5: Here here second order intermodulation is studied.

Results @ 13:07

rx7compare part5

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.

rx7compare-part2

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.

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.

rx7compare-part1

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.

AirSpy HF+ Discovery: First Impressions on Medium Wave vs. Elad FDM-DUOr

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.

Using an Airspy HF+ Discovery to Hunt for HF Beacons

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 HF Beacons With An Airspy HF+ Discovery

Fenu Radio Reviews the Airspy HF+ Discovery

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.

Over on his blog, radio product reviewer Fenu-Radio has received an Airspy HF+ Discovery, and has given it an in depth review and put it through several real world tests. Fenu-Radio notes that while the initial prototype unit that he received had some issues with overload above 19 MHz, the latest production version has completely remedied this, resulting in impressive performance that competes favorably with the high end USD$2000 Winradio G33DDC software defined radio.

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.

Fenu-Radio's Airspy HF+ Discovery Review Unit
Fenu-Radio's Airspy HF+ Discovery Review Unit

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.

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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.