SDR Cape for BeagleBone

In the old days if you wanted to listen to shortwave you had to turn a dial. Later, you might have been able to tap in a frequency with a keypad. With modern software-defined radio (and the right hardware) you can just listen to the entire high-frequency spectrum at one time. That’s the idea behind KiwiSDR, an open source daughterboard (ok, cape) for the BeagleBone.

The front end covers 10 kHz to 30 MHz and has a 14-bit converter operating at 65 MHz. There is a Xilinx Artix-7 A35 FPGA onboard and a GPS, too. The design is open source and on GitHub.

The interface uses the OpenWebRX project for a powerful HTML 5 interface. You can see a video of its operation below or, if you can get one of the four available slots, you can listen online. From a network point of view, the demo station in Canada worked best for us. However, there are also stations in New Zealand and Sweden.

Reading a huge swath of spectrum at once is a different approach from the trunked radio SDR we covered earlier this month. That project used multiple SDRs to divide a wide band into easy-to-process slices. You could use a KiwiSDR to replace a pan adapter and never have to worry about tuning it.

Thanks [Mike] for the tip.

24 thoughts on “SDR Cape for BeagleBone

        1. It really doesn’t perform well… It seems to be more than just NF related though. If it were just NF, an external LNA would significantly improve the overall performance by lowering the chained NF.

  1. I think the HackRF One goes up to 5 or 6GHz. At least the Rad1oBatch from the CCCCamp does, which is derived from it. It uses a converter to use a 2,5GHz chipset. So the A2D does not need to cover the whole band, just the bandwidth which is used.

      1. A bit of a weird question. But I’ll flip it on its head first.
        Direct sampling gives you all the power at each frequency.
        When down converting half the power goes to f+lo and half goes to f-lo. So you need to band pass filter the side that you want to keep, usually the lower one (and attenuate the one that you do not). So literally you are throwing half the power away.

        So in an ideal world if you could get cheap 12GSPS ADC’s you would use them instead of a down converter, if you were looking at RF signals between 5GHz and 6GHz.

        1. But then you do not only need this 6Gs/sec ADC but also processing speed and memory to process that amount of data. So the next step would be filtering and down conversion anyway. Although theoretically this can be done more “ideally” in the digital domain.
          And 12Gs/sec sampling with sufficient dynamics is more something for a high end laboratory equipment (e.g. oscilloscope) with a 6 figure price tag than for a radio receiver
          You could do undersampling, e.g. sample your BANDPASS FILTERED 5GHz to 6GHz signal with 2Gs/sec. Of course you need a good, fast sampling stage for this and the end result is, of course, the down converted signal.

  2. It is odd that the article doesn’t mention that KiwiSDR has a Kickstarter going on right now. Thy are a little over half way to their goal. Although I don’t have enough interest to buy and set up a unit myself, I offered the project $20 as I do have enough interest to want to connect to a remote KiwiSDR and listen in once in a while.

      1. Maybe HaD is like me and they don’t want to get into the quagmire of linking themselves to kickstarters anymore. While still wishing to support the concept and open source aspect of some projects.

        But either way, they gave the link and following the link made it clear there was a kickstarter. And if people are so disinterested that they don’t even click the link they aren’t likely to invest.

  3. Unrelated to this specific kickstarter I just want to remark that due to the many previous and ongoing bullshit kickstarters you see constantly popping up I have pretty much lost all confidence in the concept.
    For me the bad apples, and that those are not being successfully picked out of the basket by the management, have ruined the thing for a large part :/

    I blame all the assholes that misuse kickstarter sites for attempting to defraud people, Because I know how hard it is for a normal somewhat positive person to prevent such misuse of your project and there is only so much you can do.

    1. how do you expect kickstarter to figure out who is going to be successful or not?

      they try to weed out outright fraud, but beyond that kickstarter and similar are ways to fund projects YOU judge have a good chance at succeeding and want to support.

      So you are blaming kickstarter for your bad judgement (aka bad luck)

  4. Many thanks for the feedback and comments I have received. And for the many listeners world-wide that have tried the SDR. I can see from the logs that not all connection attempts are successful. Although I have fixed a number of bugs there are still problems with some, possibly older, browsers. If you’ve had problems in the past please try connecting again. I have added much debugging code to try and understand the issues. If possible, try and use the most recent versions of Safari, Firefox, Chrome or Opera that support HTML5. Thank you.

  5. Many thanks for the feedback and comments I have received. And for the many listeners world-wide that have tried the SDR. I can see from the logs that not all connection attempts are successful. Although I have fixed a number of bugs there are still problems with some, possibly older, browsers. If you’ve had problems in the past please try connecting again. I have added much debugging code to try and understand the issues. If possible, try and use the most recent versions of Safari, Firefox, Chrome or Opera that support HTML5. Thank you.
    http://1tour.vn

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