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Thread: Enhanced PyDSA software spectrum analyser using Rigol DS1054Z scope

  1. #1
    dtrewren's Avatar
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    Default Enhanced PyDSA software spectrum analyser using Rigol DS1054Z scope

    Good afternoon everyone,

    I thought this might be of interest to anyone needing a spectrum analyser but not wanting to spend a fortune.

    I am embarking on a WSPR project and wanted to build/test my own RF PA and filters and generate some nice plots to document the project. To that end I needed a spectrum analyser but didn't want to shell out shed loads of cash for occasional use.

    I found a software spectrum analyser PyDSA using a Rigol oscilloscope as a sampling front end. I took the original software design and enhanced it so that is was calibrated against a known input signal and was immune to changes in oscilloscope signal levels.

    Rather than wittering on in text I have wittered on in a video to show what the analyser can do and what might be done to further enhance.

    Hope you like, comments or suggestions (non rude ) very welcome.

    Cheers,

    Dave (G7IYK)



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    Super Moderator pmh's Avatar
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    Good work. Spectrum analysers are a great bit of kit but, as you say, are expensive for occasional use.

    Kind regards,



    Phil

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    dtrewren's Avatar
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    Cheers Phil,

    I surprised myself with the level of restraint exercised in order to resist the temptation of buying the Rigol analyser

    Once I get going with the RF PA and filters I will crack on and incorporate the tracking generator mode.

    So many projects and so little time (need to retire PDQ) !

    73's

    Dave

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    Super Moderator pmh's Avatar
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    Interesting to see how you got on.

    I ended up with a Siglent scope as it had a better spec, and higher frequency, for the same price.

    Kind regards,



    Phil

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    dtrewren's Avatar
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    I will add updates to the thread as the software gets enhanced

  6. #6

    Default is the code available?

    Is the code available for this project? I have the original code running on my pc with the ds1054 and these enhancements look great!

    Gene

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    dtrewren's Avatar
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    Hello Gene,

    This is very good timing. I have been using the spectrum analyser quite a bit working on my stand alone WSPR beacon (soon to be published).

    In the last week or so I have added more functions to the analyser .... peak search, delta marker and offset measurement. I am in the process of adding control for a low cost signal source to act as a tracking generator. This will allow frequency response plots to be made. Also the ability to store multiple plots in different colours.

    I am on holiday at the moment for a few days. When I get back will finish and test the modification then will post a link to the code.

    Cheers,

    Dave

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    Hello All,

    Not sure whether to add to this thread or start another .....

    I have been making lots of modifications and enhancements to the PyDSA spectrum analyser. I intend to make another little video
    to show the changes but in a nutshell ...

    Today's work covered the following:

    - Correct calibration into a 50ohm load
    - Peak markers
    - Delta markers and delta power in dBc
    - Tracking generator support using a FY6600 signal generator
    - Multiple trace store and clear

    The purpose of all this development has been to support my WSPR stand alone beacon project such that I can better document the RF output and filter responses.

    Attached is a plot from the enhanced spectrum analyser showing three traces.

    - The brown trace is the response of the 20m filter from QRP labs using the tracking generator feature I have added
    - The yellow trace is the output of the PA with no filtering , peak output is about 32dBm (30dB attenuator in place)
    - The red trace is the filter PA output using the QRP filter

    It can be seen the filter is attenuating the 2nd harmonic by around 35dB

    Any comments/suggestions very welcome before a proper write up.

    Cheers & 73's,

    Dave (G7IYK)


    Spectrum analyser 3 plots.jpg
    Last edited by dtrewren; Wed 9th May 2018 at 20:28.

  9. #9

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    Hello Dave,

    Will you be able to share the source code, please? I'm looking forward to trying these features.

    Many thanks,
    Krzysztof

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