Software Defined Radio Vlog Part 4 - Frequency Scanning

I’ve replaced the local oscillator with a Spartan-6 FPGA and scanning with it’s internal PLL.

I show VGA output, IQ processing, 256 point FFT and audio from one bin. The final details will be published with the next Element14 video about communication…
Video Rating: 4 / 5

42 replies
  1. Aleksandar Markovic
    Aleksandar Markovic says:

    Wow! You really want to replace hole PC and use one FPGA 🙂 What to say …
    you rulez! Maybe you just need an little tweaking in analog part (I/Q
    demodulator + OP) to improve noise figure.

    Reply
  2. William Stillwell
    William Stillwell says:

    @JeriEllsworthJabber would be cool if you can build a decoder for the HD
    Sidebands , love this project, very simular to Flex Radio or SDR-IQ Radios
    used by many amateur radio operators.

    Reply
  3. Jeri Ellsworth
    Jeri Ellsworth says:

    @mikikg Most of my analog design is driven from the fact I have to use
    small single sided boards. I could do a better layout if I had a layer to
    route power.

    Reply
  4. scottrharris
    scottrharris says:

    @jeriellsworth Cool. I was reading up on it last night (along with
    investigating DCM stuff. It seems like you could generate the quadrature
    signals there instead of using 4 times the LO and then doing the two D
    flip-flop quadrature shuffle). Hoping to get one going on the Xula-200 I
    won in the 555 contest.

    Reply
  5. Jeri Ellsworth
    Jeri Ellsworth says:

    @mikikg I still don’t have a filter on the front end, so that’s
    contributing to the noise. The noise is not a concern of mine now.

    Reply
  6. preben01
    preben01 says:

    Finally I can understand how a chip is really made by watching your videos.
    People always say that making a ASIC is a million dollar project. Is that
    true? If you are employed by a chip making company and have the tools at
    hand, how expensive is it really?

    Reply
  7. w2aew
    w2aew says:

    @JeriEllsworthJabber @ChrisGammell Actually – there is a entire community
    within the ham ranks that still love and exclusively fiddle with AM
    (ancient modulation). They love the nostalgic sound and wider modulation
    BW…

    Reply
  8. Jeri Ellsworth
    Jeri Ellsworth says:

    @AntiProtonBoy It’s the smallest butterfly architecture that Xilinx offers.
    It takes quite a few passes to calculate to result. I think it was ~40-50
    clocks.

    Reply
  9. Aleksandar Markovic
    Aleksandar Markovic says:

    @jeriellsworth Absolutely understand Your goals, just keep on going …
    this was a side notes … I’m working on similar SDR project but my goals
    is to get maximum SNR and dynamic range out of analog part. Once again, you
    did a great job!

    Reply
  10. Jeri Ellsworth
    Jeri Ellsworth says:

    @scottrharris I am using the free FFT core. It’s configured to be burst
    oriented. I tried the streaming configuration, but it took up too much dsp
    resources in the tiny FPGA.

    Reply
  11. Jeri Ellsworth
    Jeri Ellsworth says:

    @hazydave This is a direct conversion reciever, so I’m using a 4x square
    wave to drive a 4066. Check out the Tayloe detectors.

    Reply
  12. whydontyoublogabouti
    whydontyoublogabouti says:

    @hazydave Is a low pass filtered LO necessary, since it’s a digital mixer?
    The square wave generated by the FPGA should actually be pretty clean, but
    it looks worse on the oscilloscope than it is because of the huge loop area
    (have a look where the CRO probe’s ground is clipped)

    Reply
  13. CurtisStephenson
    CurtisStephenson says:

    Your progress vs time on this just amazes me. Great work! Will you be using
    a reference design for the DSP or doing your own? Also how are you planning
    to control and configure the device when disconnected from the PC?

    Reply
  14. aztek man
    aztek man says:

    I must be a NOOB. I would love to understand exactly what the practicality
    of what Jeri is doing. Jeri, maybe a show of what the reason is for doing
    this to the thing-ama-bob you are creating. THANKS!

    Reply
  15. Jeri Ellsworth
    Jeri Ellsworth says:

    @CurtisStephenson The device will configure from the built in flash. I’m
    not sure what the user interface will look like. I may not put much effort
    into that at first. (few buttons)

    Reply
  16. Jeri Ellsworth
    Jeri Ellsworth says:

    @karmicthreat I’m doing it because it’s a neat circuit. ADC are very
    expensive if you want something in 50mhz or more range.

    Reply
  17. Jeri Ellsworth
    Jeri Ellsworth says:

    The simple boards will avoid all the time and confusion of built in
    peripherals that need to be held in a stable state when you are not using
    them.

    Reply
  18. Angel Guerrero
    Angel Guerrero says:

    wow! you are awesome… there is not many ladies out there that like play
    with electronics and hardware, I fell very identified with part of your
    story, digging into toys and electronics, I used to similar things.. but
    less lucky than you.. where I born and I came I did not have electricity at
    my home until I have 14, no television, only very old Russian radios that I
    use to take apart.

    Reply
  19. w2aew
    w2aew says:

    We’re gonna turn you into ham yet! Looks great Jeri! Can’t wait to see what
    you do with filtering and demod in the FPGA.

    Reply
  20. 300000hp
    300000hp says:

    nice job! what would be the maximum scanning frequency for this radio? and
    do you planning to make some finished board or you just playing around with
    this stuff?

    Reply

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