AGC and Signal Strength: how to jump in EP calculations

Environmental Forum Forums EddyPro AGC and Signal Strength: how to jump in EP calculations

This topic contains 3 replies, has 3 voices, and was last updated by  vitaly 5 years, 9 months ago.

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  • #1462

    vitaly
    Participant

    Hello All,

    Some time ago I’ve updated LI7500 embedded software from 6.0.0 to 6.5.2, and the meaning of diagnostic value changed accordingly, due to AGC was replaced by Signal Strength. But I would like to process my 10-Hz ASCII data (which contain diagnostic value) uninterruptedly. Since there is no “embedded software” field in dynamic metadata file,whether is it an appropriate way to “calculate back” older AGC-based diagnostic values using linear correction: AvSS=(100-AGC)/0.56, and then process all the data in EddyPro with “LI7500A embedded software version” setting on “6.5.0 and above”?

    Thanks.

    #1849

    gerardo
    Participant

    Hello Vitaly,

    I am not sure the procedure you suggest is appropriate. I would strongly suggest simply splitting the dataset in two parts and perform separate runs using either diagnostic.

    Thanks,

    Gerardo

    #1851

    IsraelB
    Keymaster

    Technically speaking there is no equation that relates AGC and Signal Strength.

    However, they are both represented in the same manner in the diagnostic value. It is only the naming and associated meaning that changes. For example a Diagnostic Value of 245 for embedded version 6.0.0 will have a binary representation 1-1-1-1-(0-1-0-1) the last four of course represent AGC and it will be computed by converting the last four to decimal (which will be 5 in this case) and multiplying by 6.67 (5*6.67 = 33.35). So for this instrument AGC = 33.5 and it is in good condition. If the diagnostic value was the same for a version 6.5.2 instrument since the calculation is the same you will get a signal strength of 33.5 which is very much lower than the good signal strength in the 90-100 range.

    A diagnostic value with a good signal strength for version 6.5.2 will be something like 254 which has a binary representation of 1-1-1-1-(1-1-1-0). The last four digits convert to 14 in decimal representation and the calculated signal strength is 93.38(14*6.67=93.38).

    So as you can see the computation from the diagnostic value is the same and that is what EddyPro does. However what goes into the diagnostic value and what it means in terms of instrument condition has totally different meaning.

    In the end, I think it might be much easier to process them separately.

    #1853

    vitaly
    Participant

    Thank you for your answers,

    I agree that separate processing will be easier, moreover, re-calculation of diagnostic value could be a source of hidden errors.

    Previously I thought that EddyPro has some features which could be applied only to whole-year dataset, but as I clarified recently, it was a delusion.

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