NBitWonder

Fun with Software-Defined Radio

by on Dec.12, 2011, under Experiments, Projects, Software Defined Radio

As you may know, one of the projects in the pipeline here at NBitWonder is a software-defined radio receiver, loosely modeled after Jeri Ellsworth’s receiver published earlier this year.  As of this past weekend, NBW-SDR (as we call the project) is operational!

The video features a live reception of WWV, one of the United States’ atomic clock stations (much more information here).  The station is located near Fort Collins, Colorado, some 2000 miles from the receiver’s location in Virginia.

There is much more work to be done on the software, as you can tell from watching the video.  For instance, only AM reception is implemented right now.  The signal processing functions still need some work, and more appropriate gains should be chosen for the entire signal chain.  Still, it is rewarding and reassuring to see the project working at some level.

Be sure to watch the github repository and the forum for much more information as project development proceeds.

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6 Comments for this entry

  • Tony P
    December 21st, 2011 on 5:50 PM

    Kit this baby up and sell it for $100 and I’ll buy one!

  • Ben
    December 21st, 2011 on 11:16 PM

    Thanks, Tony!

    We don’t have immediate plans to make this into a kit, but we’ll let you know if that changes. Thanks for your support!

  • John
    December 22nd, 2011 on 10:11 AM

    If you decided to do a Kickstarter project for this, or any other fund gathering drive, please include me in that list. I and other Midsouth Makers would gladly contribute to this

  • AE5PH
    December 22nd, 2011 on 4:44 PM

    It is interesting that you are using a Maxim DS1085 for your x4 local oscillator. The accuracy and frequency stability of the device are problematic. I’m using it in a radio application as a signal generator for an antenna analyzer. I have to feed back the signal output by the DS1085 to a frequency counter in my microcontroller to adjust the frequency closer to what is desired. Even then, I can only obtain an accuracy of about 1 KHz. I may yet switch to a more stable device for that application.

    For my SDR applications, I use a Silicon Labs Si570. True, it is an order of magnitude more expensive, but much more accurate and stable. The Si570 is used a lot in SDR applications. I think that much of the noise and distortion you are currently experiencing is due to the DS1085.

    73

  • AE5PH
    December 22nd, 2011 on 5:08 PM

    Forget my previous comment. I found a link to the SDR thread on the forum. You’ve already reached the same conclusion and you are already using the Si570. That’s what I get for not chasing down all of the information on the project.

    73

  • George
    December 22nd, 2011 on 7:25 PM

    No worries, happens to all of us ;-) If you want even more information about the state of the SDR thus far, check out our github repository for the SDR. The “Documentation” section of the hierarchy contains Ben’s project notebook, which is a reasonably detailed narrative of the SDR build progress thus far.

    Thanks for looking into the project, we love fans!

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