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Friday, February 17, 2017

Back from the Raspberry Pi SDR Brink

Earlier this week I shocked Pete Juliano by telling him that I was taking a break from my normal analog, discrete component, no-chips mode of construction so that I could put together a Raspberry Pi-based SDR receiver.  Even from 3000 miles away, his astonishment was clearly perceptible. He seemed briefly disoriented by it.  I'm sure some of you may have a similar reaction.  

I'd been lured in by that video of the Raspberry Pi RTL-SDR receiver with the very cool  touch screen display.  It has a waterfall!  And a touch screen! How could I resist?

I went to Amazon, but there I discovered that that attractive display is not exactly cheap. And maybe I'd need a new Raspberry Pi.  At this point, in search of economy and convenience, I began rummaging through my digital junk box.  There I found a Rasp Pi Model B.  And an old computer monitor.  This will be easy, I thought.  Just get some SDR code into that Pi, hook up the RTL-SDR dongle and Bob's my uncle, right? 

Not so fast.  I quickly began to run into daunting digital obstacles. Sure, the Raspberry Pi fired right up and filled the computer display with lines of code.  But it was all Linux.  Yuck.  Sorry Linux fans, but for some of us mere mortals,  Linux is a weird opaque world in which every little thing is somehow a lot harder.

I also began to suspect that my 2013 Model B might be sort of a Model T in the Rasp Pi world.  It might not be up to the computing task.

And finally, as I poked around the internet, I began to conclude that the Raspberry Pi software for SDR is not quite done yet.  All the sites seemed to have the word "experimental" in there.  And lots of "I'm pulling my hair out" comments Maybe I'm wrong, but maybe we just need to give this more time.

Let me ask the distinguished group some questions:

Is my Model B really useless for SDR purposes, even if I don't need all the bells and whistles?

Is there an SDR program that can be easily placed in a Raspberry Pi by someone who has NOT mastered the mysteries of Linux? 

For now, I have cleared the raspberries from the bench and am back to working on HDR stuff. 


  1. It's only a mystery to you because you have not started the journey. The journey begins with the first step. If you are going to experiment with a Linux SDR, I'd suggest that you start with one of your roadkill PC's. Unbuntu or similar.

  2. Grasshopper, for one so used to slaying solder and smoke, discrete components, phase noise, and manhatan pathways, Linux is just another step on the path to enlightenment.

  3. Bill, you might want to explore the more "canned" SDR solutions as you work to slay your inner SDR n00b. Airspy + SDRsharp come to mind. At the other end of the SDR ecosystem are the Gnuradio based approaches (far more powerful, more amenable to experimentation) with radio hardware such as LimeSDR, Ettus/NI devices, RTL-SDR dongles, and so on. Build on success, but don't start in the deep end - there be dragons..

    SDRsharp runs on Windows, but if you truly want to experiment, then work on overcoming your Linux barrier.

  4. You can use a rasp B and works just fine. I advise you to use it with rtl_tcp and stream the control of the sdr over the lan to a Windows machine running sdr sharp

  5. Bill,

    the best (and kewlest) thing you can do in Linux with RPi and ham radio is

    1) boot the lil bugger up
    2) get a term window (xterm lets you type at the command line like window and mac)
    3) type apt-get update (collects all the available software into a local database)
    4) then apt-get install fldigi (recognize anything?:)
    5) After that has installed go to your menu under "internet goodies" (or something like that) and you'll see FLDigi sitting there happy as a clam in a mudflat
    6) open fldigi and have a ball

    NOTE: Raspberry Pi B's and older don't have a boatload of audio capability so if you want to TRANSMIT as I have using a Signalink and IC700 then you may need a Wolfson Audio card.

    In the end for $35 on Amazon the newest Pi is the EEI Play with me!" bargain of the century.

    Have Fun!

    Rob, KC4NYK

  6. Take a look at Medo's guide to SDR on the RPi3.

    It's a step-by-step walk thru and covers both Hardware and Software.

    Good Luck and 73!


  7. Or you could build a microwave L.O. like i just did and loose the rest of your hair. I think ill put linux on this computer just for some relaxation.... Hi Hi


  8. I suggest you build a simple regen receiver, sit down, and contemplate the error of your ways. Hi


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