Review of the Airspy R2 SDR Radio

Could there be a radio better than the Sony XDR-F1HD?  My answer would have been a resounding “no,” that is, until I came across the Airspy R2.

The Airspy R2, which retails at $169 as of the time of publication, is a software-defined radio, or SDR.  A “mini” version with a few less bells and whistles retails for $99.  With an SMA to Coax adapter, $5 on Amazon, the supplied USB wire, and free SDR tuning programs (more on that below), you have all you ever need for DXing.  Let me repeat:  this is the only radio that you will ever need for FM DXing, with one small caveat.

SDR Radios – better than real tuners?

Many DXers have jumped on the SDR “bandwagon” in the past decade.  Up until 2017, I was largely “old school,” relying on actual tuners to DX.  I dabbled with SDR radios in 2014 with the RTL-SDR USB dongle, but the inferior technology of the RTL-SDR made me want to never use an SDR again.  A fellow DXer, Les Rayburn, generously gave me an extra Airspy R2 that he had a few months ago.  I expected to hear medicore quality like I did with the RTL-SDR.  Instead, I was blown away.

The Airspy R2 vs. other radios

The R2 is better, more sensitive, and more selective than the Sony XDR-F1HD.  Some DXers may disagree with me on this, but I have proof: on 6/16/17, while strong DX up to 200 miles away was pounding into my shack, the XDR received local 88.5 WAMU Washington, DC @ 21 miles as usual with HD Radio decoded.  At the same time, the Airspy’s analog reception of WAMU was muddled with interference from 88.5 WHRG Gloucester Point, VA @ 99 miles.  Had I not been using the R2, I would’ve not logged WHRG.  I often hear weaker signals first on the R2 before the XDR picks it up.

RDS is much stronger on the R2 than XDR.  When 98.3 WHRF Belle Haven, VA @ 108 miles came in on 6/16/17 over local WSMD, The R2 received clear RDS from WHRF, while the XDR had a hard time picking up WHRF at all, let alone with RDS.

There’s still one thing the XDR-F1HD has going for it that the R2 doesn’t has: HD Radio.  The R2 can “see” the HD Radio sidebands of FM signals, but it can’t decode them like the XDR does.  If the Airspy did decode HD, I’d probably not use the XDR radios again, other than for screenshots of digital text.

SDR tuning programs

Having the Airspy R2 radio in your shack is only half of the equation.  You need a good software-based program to read the data received from the Airspy radio before you can actually DX.  There are many different SDR programs out there, and from what I’ve seen, all are free.  While installing these programs and calibrating them for suitable use with the Airspy may require some technical expertise, you can usually get up and running within an hour.

I use two programs with the Airspy R2:

SDR# (download link)

and SDR Console (download link)

Both programs only receive data from the Airspy R2, so reception (in terms of selectivity and sensitivity) are identical in both assuming the settings are calibrated correctly.  SDR# seems to be more user-friendly and uses less CPU, while I like the RDS screen on SDR Console much better.

SDR# and SDR Console can show an entire “swath” of the FM band.  The “bulges” appear where signals are, and they fluctuate up and down with the actual signal’s changes in volume, much like an EQ meter in a stereo system.  A “waterfall” function (seen on the SDR# screenshot and also available on SDR Console, although I have it turned off in SDR Console since it distorts the RDS area in the program) shows a vertical waveform from each station received.

What I really like about either program is that it shows you which signals have HD Radio in your area.

Note the mountain-like signal from local 101.5 WBQB.  This is what a normal analog signal that doesn’t run HD Radio appears like in SDR#.

This shows two frequencies in my area that run HD Radio, 103.5 WTOP (left) and 104.1 WPRS (right).  Note the two rectangular “bands” of their digital signals surrounding the center analog signals, which looks much like WBQB’s above.  When looking at a swath of the FM band in either program, I can immediately see which stations have IBOC running or not, without having to tune the station in.

In either program you have a high ability to customize the radio’s parameters.  You can adjust the sensitivity gain so weaker signals can be heard, or so overloaded signals can be tamed.  You can also adjust a virtual “IF filter” to improve on selectivity.  Please contact me if you need help determining the right settings for your SDR program, as this is beyond the scope of this article.

Recording 8 MHz of FM at once

Perhaps the largest benefit of using an SDR radio, outside of their great performance with minimal financial burden, is the fact that you can record 8 MHz of FM radio at once.  This means during a strong FM Es opening, you can easily record, for example, 88.1 FM to about 95.9 FM at the same time.  Or, you can record consecutive upper band frequencies in the same 8 MHz “swath.”  When you hit “play” on the recorded file, you can DX within the recorded 8 MHz live, change frequencies within that 8 MHz, hear every signal received, and receive RDS decodes from all applicable frequencies.  This is very helpful during Sporadic E openings, as you can “set it and forget it,” and then DX the entire opening at your leisure at a later time.

The downside to this function is that it is entirely dependent on the quality (and speed) of hardware your computer.  If you are using an old computer, it may only record 2 or 4 MHz.  A brand new gaming PC may record 10 MHz or more.  You can’t DX outside of the already-recorded swath of MHz when listening to a recorded file, so if you recorded the top portion of the FM band, you cannot go back down to 88.1 and DX up to 95.9 FM.

Space is also a major issue.  You will need an external hard drive in the multiple terabyte range to make use of this function.  At the highest setting, 1 second of 8 MHz can cost you 76 MB of disk space, or 4.5 GB a minute.  Personally, I don’t use the recording function as I have yet to have a strong FM Es opening since I got the Airspy.

DX screenshots

Programs that utilize the Airspy R2 are a great benefit for those who like to receive and screenshot RDS, such as what you can find in my RDS/HD Radio screenshots gallery.  Both SDR# and SDR Console offer quick, often instantaneous decodes of RDS from capable signals.  For strong signals, you can often receive a compatible station’s RDS PI, PS, and PT codes within a split second of tuning.  The PI code, which usually is a slam dunk ID for most stations, is usually the first bit of information received from RDS, meaning a weak signal can often be positively identified.  You can go to the RDS PI Code Converter website, type in the received PI code, and usually get a positive station ID, if the SDR program you use doesn’t already display the call letters.

The SDR# program displays RDS under the frequency area as follows:
[RDS PS] – [RDS PI code] – [RDS RT radiotext]

RDS received via SDR# from 105.3 WNOH Norfolk, VA @ 135 miles.

The SDR Console program shows RDS as follows:
[RDS PTY] Frequency (“thumbs up” icon for decoded RDS)
(Call letters derived from PI code)
[RDS PI code]
[RDS RT radiotext]

RDS received via SDR Console from 98.1 WOCM Selbyville, DE @ 116 miles.  Note how SDR Console automatically decodes the call letters (“WOCM”) under the frequency based on the RDS PI code, which is also displayed near the center in large text.

RDS received with the Airspy isn’t foolproof in regard to a positive ID, especially when it comes to the PI code.  While most PI codes are correct, stations owned by iHeart Media often show incorrect codes.  This is not a downside of the Airspy and is, instead, a problem originating with the broadcast station(s).

Note this RDS decode from iHeart station 97.1 WASH Washington, DC and the derived call letters on the second line (“KCMD.”)  Obviously, as you can see this is a positive decode from WASH, the KCMD call letters are incorrect.

I also found that LPFMs and translators that run RDS, when received by the Airspy, will either display a bogus PI code, or the PI code for their full power parent station, if applicable.

Traveling with the R2

The Airspy radio also revolutionizes traveling as a DXer.  Up until now, successfully DXing while traveling usually meant either only using a rental car radio, or lugging around the Sony XDR-F1HD, a Sony minidisc recorder to amplify the XDR’s audio, and portable speakers.  This was less than ideal, given how delicate the XDR radio is.  The space the needed items took in my carryon bag (including padding to ensure the XDR radio didn’t get damaged) left little space for other things, and it also caught the attention of TSA officials more than once (although they didn’t care what it was once I explained).  Additionally, the setup in a hotel room also was clunky, with wires everywhere.

While using the Airspy R2, all that I now need is my ASUS tablet, the Airspy, its supplied USB cord, and rabbit ears or a dipole to get the same level of reception (sans HD) that the XDR-F1HD receives.

Other uses for the R2

Beyond FM DXing, the R2 can receive anything within 24-1800 MHz.  An add-on SpyVerter converter can get 1 KHz to 60 KHz  This means you can listen to live aviation, ham radio, store security, CB, NOAA, and public safety broadcasts, assuming you are in an area that can receive such signals.  The R2 doesn’t decode encrypted or restricted broadcasts (such as some police or military transmissions), however.

Final verdict

Ignoring the fact that the Airspy R2 cannot decode HD Radio, I would say this is, hands down, the best FM radio available.  It is tiny, robust, and has stellar selectivity/sensitivity that is better than the Sony XDR-F1HD.  The customization of settings, as well as the ability to directly screenshot RDS decodes without having to use an actual camera makes this radio lightyears ahead of the 2008-era XDR-F1HD.  The R2 is the radio I now recommend to new DXers, and to those who wants the best at a cheap price.