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

The highly anticipated AirSpy HF+ Discovery SDR has been in the hands of early adopters for about two weeks–and I’ve seen nothing but positive comments!

After a long run (2007-2013) with a Microtelecom Perseus, my SDR of choice became the Elad FDM-S2, and more recently an Elad FDM-DUOr “hybrid” SDR receiver. The two Elads have the same core processing components and identical performance when the DUOr is connected via SDR software.

This week I’ve compared the HF+ Discovery ($169) against the FDM-DUOr ($899) using Studio 1 software and identical modes & settings. The following video features the radios’ performance on a crowded daytime medium wave band from suburban Seattle-Tacoma USA.

Click here to view on YouTube.


  • Software used is two “instances” of Studio 1, version 1.06e
  • Antenna is an east-west oriented Wellbrook ALA1530LNP Imperium loop
  • Mode, filter bandwidth, AGC, etc. are the same for each radio
  • 768 kHz sampling bandwidth used for both receivers

Stations tuned are:

  • 1320 KXRO Aberdeen WA, 74 miles @ 5 kW (in-line with antenna)
  • 1110 Oak Harbor WA, 78 miles @ 500 watts (in antenna’s null)
  • 1040 CKST Vancouver BC, 147 miles @ 50 kW (in antenna’s null)
  • 1430 KBRC Mt. Vernon WA, 85 miles @ 5 kW (in antenna’s null)
  • 750 KXTG Portland OR, 118 miles @ 50 kW (in antenna’s null)

I purposely sought out signals difficult to hear in the presence of powerhouse stations. Only 1320 kXRO (in-line with my antenna) and 750 KXTG are what you might consider average or fair quality signals. Headphones are recommended for most of these, particularly 1040 kHz.

You’ll note that the pass band has been “pulled” over the edge of the carrier frequency by a few hundred Hertz. This is an excellent trick that can often reduce noise and/or improve intelligibility. It’s a feature unique to Perseus, Studio 1, and SDRuno software; it works in sideband modes and in selectable sideband Sync AM (SAM) mode.

After listening to the signal comparisons, what are your thoughts on the HF+ Discovery? Please leave your comments below.

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

Spread the radio love

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

  1. Donald Chitester

    Couldn’t even pick up WWV from Boulder with HF+ Discovery (public library w/SDRUno and me for antenna), so became discouraged and sold unit on ebay (to you!). Wish I had asked more now. Had read your article was one of my reasons to purchase! I think I will save up for different one. Android won’t get a driver for it apparently, and power problems aren’t solving.

  2. Stephanie Battaglino

    Thanks for the video,Guy. I can tell you that having just received the Discovery last week and hooking it up to my Wellbrook – the LNP version as I live in a condo community and have it positioned inside my window, it has so far proven to be wonderful at dealing with – and filtering out – the “seasonal static” that comes along for the ride with summer time MW DX. I also own its predecessor, and given the filtering improvements that come along for the ride in the SDR# software, I’d say it’s doing very well in comparison. I also own the Elad, but have yet to see how that performs in comparison to the Discovery, but plan to do so soon! So far, quite pleased – and you really can’t beat the price for the performance you get in return.

    In your vid you are running HDSDR, correct?

    1. Guy Atkins

      I’m running Studio 1 as the software. I like it for a lot of reasons, one of which is the flexibility for running two “instances” of the program for separate SDRs (FDM-DUOr and Discovery in this case). I can position the spectrum / waterfall displays for each radio the way I like… especially useful for an ultrawide-style 2nd monitor.

      By the way, the old version 1.22 of SDRuno (which is based on Studio 1 code) is freely available. It contains an .EXE file that is specifically for “EXTI dll” based radios. It works fine with the Elad, Perseus, and AirSpy radios… the SDRplay receivers too, as long as you add the appropriate EXTIO file to the program folder. There is a lot I personally like about the GUI and features of Studio 1 and SDRuno.

  3. Ryan Herbrechtsmeier

    It seems like the ELAD just edges out the Airspy HF+ Discovery but not by much. Even though the HF+ Discovery is slightly weaker, it really helps that the price point is much lower (170 bucks!) which is more of an offset to the marginal weakness that I heard. That’s pretty nice to be honest, I hope this spurs more competition and development in sub-200 dollar SDRs.

  4. Vince

    No difference to my tinnitus plagued hearing. Even the very little difference some have noticed must take into account the cost difference between the radios.

    It seems to me we are finally able to say there is such a thing as a ‘nearly free lunch’ in the SDR realm.

    I’m convinced, just a matter of placing the order now. :^)

    1. Guy Atkins

      DREAM works as a 3rd party program with most or all SDR software. You just need to do the setup with virtual serial ports to connect them. For the occasional times I have tried to decode DRM on shortwave, I have used Elad’s FDM-SW2 software because it has native DRM support (no DREAM add-on needed).

  5. Thomas

    Wow–thanks for sharing this, Guy. The fact that the $169 Discovery can even compare with the likes of the ELAD DUOr is kind of amazing.

    With headphones on, I’ve closed my eyes to listen to these samples. I can detect when you’re muting/unmuting each receiver. To my ears, there’s very little difference in the samples. In terms of intelligibility, the results are nearly identical.

    Thanks for putting this together and for making such a level playing field for the A/B comparison.

    1. Guy Atkins

      You want to ignore the noise floor level and concentrate on the S/N level. The Discovery’s auto gain setting is very “smart” and adjusts the gain on its own for the best reception in the presence of any strong signals on the band.

      NF levels can be misleading…that’s tripped me up more than once! Compare the S/N results and also trust your ears :^)

  6. Sergio Potes

    Guy thanks for the video. They sound very similar. I like the Elad Duo.I used mainly for swl and qrz. The Airspy is very good too. Thanks Sergio


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.