Confessions of an SDRaholic: when 4.5 terabytes is not enough

WinRadioExcaliburFullScreen Alas, ever since I started using Software Defined Receivers (SDRs) last year, I’ve found that I fill up hard drives faster than I can buy them. As you may have noted, I like to make spectrum recordings–especially during the night-time hours, as I slumber. The following morning, upon waking, I’ll “tune” through, say, the 31 meter band as if it were live. What makes it even more amazing for me, is that I can fast-forward through time and scan for DX stations even more quickly.  Great fun–highly addictive.  And did I say, space-consuming?

On my WinRadio Excalibur, I find that I use about 4 gigabytes of hard drive space for a one-hour-long spectrum recording, 100 kHz wide. Of course, if I were to record a 2,000 kHz (2 MHz) chunk of spectrum, it would chew through 4 GB in, roughly, 3.5 minutes.

Fortunately, I rarely ever record spectrum that wide. I find that the maximum width I ever record is 1.25 MHz, which I reserve for occasions once in a blue moon. Most of the time, I stick to 100 kHz-160 kHz widths.

After I record a chunk of spectrum, I usually listen to it, create an AF recording of anything of interest, then delete it from my drive. You’d think this would effectively keep my hard drive cleared out, ready to receive the next installment? Not so. Well, at least, not in my undisciplined SDR beginnings.

The flaw in my logic

Quite often, I make spectrum recordings while traveling, and do so remotely (using TeamViewer to control my PC). In the past eight months, I’ve done a lot of traveling. When I return from a trip, I find that I’ve often amassed a sizable collection of spectrum recordings. Upon returning from travel I also find (not surprisingly) that I’m typically busier than normal, catching up with email, phone calls, and delayed appointments. Thus, I never quite get around to reviewing–and therefore deleting–these files. Most of the spectrum recordings taking up space on my internal drives are those I’ve recorded remotely.

Last year, I thought I’d solve the space problem on my ailing laptop by purchasing a dedicated tower PC (Core i5) maxed-out with RAM and with a 1TB internal (7200 RPM) hard drive. This particular Gateway PC also has a bay that accepts cheap internal SATA drives; I simply insert an internal SATA hard drive in the ejectable bay, load the drivers, and it’s good to go. When I purchased an additional 2 TB SATA drive for spectrum recordings, I thought I would be set for years to come…Ah, how the mighty crumble…

As I write this today, I find I only have a total of 350 GB available on my PC. I’ve also filled an entire 1.5 TB external hard drive with recordings I plan to archive and share with a fellow SWLer.

The Tandy Color Computer 2 (or, "CoCo 2") was my first personal computer. (Image: Wikimedia Commons)

The Tandy Color Computer 2 (“CoCo 2”) was my first personal computer. (Image: Wikimedia Commons)

My, how times have changed

Reverse to the 1980s:  When I was ten years old, I thought my Tandy Color Computer 2 was the best thing since sliced bread.  Its 16 kB was surely plenty of memory for whatever I wanted to do, and the cassette tapes I used as a form of external hard drive gave me the certainty of a virtually limitless supply of memory.

Today, I doubt I could make an intelligible MP3 recording, even with aggressive compression, that would fit a 16 kB file size.

Facing the truth

The frank fact is that I’ve gotten much better at managing hard drive space, now that I’ve been doing spectrum recordings for more than a year. I shouldn’t need to buy additional hard drive space unless it’s specifically for archiving/sharing purposes. I just need to regularly face the music (or static)–dig through spectrum recordings made last year, and delete those I no longer need.

How do I manage space now? Here are my tricks for staying on the wagon, and saving both space and time:

  • Use the minimum amount of bandwidth possible while making recordings
  • If possible, have your SDR parse files into 2GB chunks. This makes it easier to delete sections of recording that are no longer needed without having to delete the entire recording. Happily, the WinRadio Excaliber allows for this.
  • Each time you create a new spectrum recording, have it saved into a specific directory with a label that will help you identify the contents.  For example, “Saturday Night Pirates” or “31 M Tues AM.”
  • Use Notepad or any simple text application and create a log sheet for the spectrum recording; make notes, then save it in the same directory as your spectrum recording.
  • When saving MP3/WAV files, use a standard file-naming convention to help you quickly ID a recording (you’ll notice all of my recordings do this). Mine follow this pattern: “StationName-Fequency-Date-StartingTimeInUTC.mp3” –e.g., “RadioAustralia-9580kHZ-05Feb13-1000Z.mp3”
  • Delete unwanted spectrum recordings as soon as you decide they are not worth keeping. If you wait a few days, you may forget that they’re okay to delete.
  • I also use my Bonito RadioJet for narrow IF recordings (of, say, one station).  It allows me to adjust filters and “tune,” but takes very little hard drive space. The same can be achieved by narrowing your SDR spectrum width to 20-48 kHz.

Are you an avid shortwave/medium wave audio archivist (aka, audio addict)?  What are your tricks of the trade?  Please comment!

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4 thoughts on “Confessions of an SDRaholic: when 4.5 terabytes is not enough

  1. David Goren

    My approach to recording SDR band captures is like assembling a collection of fine wines. I tend to record captures when there are unusual propagational openings…and while recording a whole swath of frequencies for an hour or so you can still tune around and make discoveries and even record them singly.. And then once the capture is done, you have it as long as you want to keep it.. So, on a static-y summers day I can go to the shelf and pull down “Ye Olde Auroral MW Opening 10/15/11” or “Hot Bolivian evening on 60 meters.” and I can make discoveries to my heart’s content. Since I can listen to an hour’s worth of each frequency it will take a long time to exhaust the potential of any particular capture, esp. with the ability to refilter and change. multiple parameters of reception.

  2. Myke

    I think it’s fascinating that technology has now made it such that even shortwave radio – perhaps the most stereotypically inconvenient hobby in the universe – can now be effectively “downloaded” in such undifferentiated chunks. We can now join the ranks of those with GB upon GB of new media which we never actually get around to listening to! I imagine the effect would be magnified in the SWL world, since we are so accustomed to hearing only select strands at a time, mitigated by numbers of receivers and peak listening hours and our ability to stay awake / focused / interested. This removes the constraints in a totally novel and interesting way, and one which has been proselytized to me again and again by my fellow SWL obsessives.

    But one thing I’ve always treasured about shortwave is the intimate relationship between listener and content. If you’re determined to listen to, say, Voix du Sahel, despite the deleterious effects of a solar storm, or a neighboring apartment’s sizzling dimmer switches, or an extremely inconvenient time difference, then the act of hearing that station (even under relatively poor conditions) still provides a charge. People are always excitedly sharing recordings of stations buried in the murk, just for a chance to hear an elusive interval signal or station ID. And I still believe in that element of chance, of stumbling across something unexpected and staying with it, allowing it to pull you aside for a few seconds or minutes (or tens of minutes or even hours). To me, that’s the great game of shortwave, and an approach that yields thrilling accidents nearly every time.

    That being said, I totally understand the appeal of the SDRs. I don’t think I ever turn on a radio without wondering what else I might be missing just a few kHz away, whether there’s something more stirring or exotic (or even just plain readable) on an adjacent frequency. But I also think there’s something to be said for accepting the limitations as part of the bargain; of understanding that you can never hear everything, even if you had a 500TB drive and an array of SDRs; that you’ll always be drawn in by that one thing that moves you to distraction, and whatever else is out there is just immaterial in that moment. Each catch is a story unto itself, a little moment of potential where you can say “Oh man, you’ll never believe this station I stumbled upon…”, and while SDRs may give you more of everything else, they can never give you that.

    1. Thomas Post author

      Hey, Myke–well said and I totally relate to your point of view. In 2011 and before, I would have completely agreed with you. To a large extent, I still do because it’s the mystery and serendipity of SWLing that keeps me hooked. I find, though, that recording spectrum hasn’t had an effect on that at all.

      There is only so much spectrum you can capture at once, and only so much you can listen to once recorded (hence my need for HD space). I liken my SDR to a time machine. Right now, I know of several band captures I’ve archived that I can’t wait to listen to on a night that I can’t listen “live”; say, when there’s a storm nearby or I’m travelling. So many times, I listen to a band capture and discover something new, hidden deep in the static.

      The “time machine” aspect is huge for me–being a guy who loves to listen, but whose family and work life make it difficult to stay up into the wee hours like I once could.

      And my time machine holds treasures…

      Last night, I watched a live stream of the Canadian Senate hearings where CBC president Hubert LaCroix was questioned regarding the drastic cuts to RCI. (I’ll be posting my thoughts about that later today.) The hearing was disappointing. Only one senator really spoke of the benefits of using shortwave radio and asked if RCI had lost listeners due to the switch to web/mobile only solutions. Otherwise, it was a cheerleading rally for management; painting the cuts as a catalyst for much needed change and innovation at RCI. Shortwave radio was painted as a technological anachronism. Though I didn’t expect a miracle to happen in that room, I at least expected a wrongful death inquiry. Sackville was a friend that I’ve listened to since I was an 8 year old kid.

      I do, however, have no less than 7 days worth of RCI Sackville in the form of band captures taken over the course of several months last year. This morning, as I type this, I’m listening to the North Quebec service on 9625 kHz as if it were live–this particular recording, from October 2012. The archivist in me loves this aspect of band captures; an opportunity to listen “live” again, to tune through a bit of aether that is no more.

      I also have a band capture of the entire medium wave band recorded on election night last year. Conditions were brilliant and I’m betting that this could be a fun bit of radio history for the future. It’s actually the capture that I pull out when someone is visiting my house and asks, “what do all of these radios do?”

      Also, I can take my SDR on family vacations to the coast, where conditions are superb, and record spectrum while there. It doesn’t take Daddy vacation time away from my little girls, and later, back home, I can tune through my band captures as if it were live.

      For what it’s worth, I still fire up my BC-348-Q and listen to it hours on end; tuning with it’s fairly precise analog dial. It’s 70 years old this year and still works. When I listen to stations via this analog boat anchor, I wonder what it must have meant to the original listener; most likely a radio op on a B-17 in WWII.

      Yessir. I love my time machines.

      Myke, by the way, I can’t wait to dig into some of the recordings from your trip.



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