Kiwi phase/frequency stability & Ebnaut decoding

SystemSystem
edited December 2019 in KiwiSDR Discussion
This discussion was created from comments split from: offset for vhf wspr decode.

Comments

  • HB9TMCHB9TMC
    Does anybody have data on the stability of the frequency/phase of the kiwi? I tried to decode Ebnaut (coherent PSK on VLF/LF) without success so far, but yet without a good SNR signal source.
  • G0LUJG0LUJ
    edited December 2019
    Stefan, perhaps a new topic on the subject of Ebnaut decoding?

    I have also tried without success - perhaps due to incorrect post-processing of the output audio file.

    http://abelian.org/ebnaut/software_linux.shtml
  • n6gnn6gn
    edited December 2019
    @HB9TMC
    I haven't documented the kiwiSDR onboard GPS performance but I have examined it, particularly in comparison to use of the Kiwi with an external clock. You can do the same by comparing two of my kiwis, one with a Bodnar GPSDO which generally appears to be better than 1 ppb and to not limit the phase noise performance of the kiwi with another using the on-board GPS reference.
    Bodnar referenced Kiwi
    and
    on-board kiwi GPS
    are both looking at US NIST LOS/"groundwave" signals transmitted from less than 20 km distant.
    This may not be entirely satisfactory since the on-board kiwi's GPS antenna is outdoors but not very well located.
    HB9TMC
  • HB9TMCHB9TMC
    Thanks for the links with the comparison. Although the external reference is clearly better, I think considering the low frequency used for EbNaut, phase stability/noise it isn't a problem. But I haven't done the math.
    A known problem at receiving EbNaut with the kiwi (at least on my side) is the lack of timestamps. I think kiwiclient would support timestamps, We only have to get them to the vlfrx-tools somehow. Did you compensate the buffer delay during your attempt @G0LUJ ?
  • G0LUJG0LUJ
    I ran into the timestamps issue as well and could not get a correct delay value. I moved on to other modes, but I still retain an interest in receiving EbNaut with the KiwiSDR if it is possible.
  • jksjks
    edited December 2019
    Kiwi TDoA certainly works using the timestamps embedded in the .wav file recorded by kiwirecorder when the "-w" or "-kiwi_wav" argument is used (IQ mode files only).

    There is some example code in kiwi/wavreader.py of the kiwiclient repo that shows how to extract the timestamp info from the .wav file.
    G0LUJWA2ZKD
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