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  1. Data Management
  2. DM-35640

Fix units of accelerationPSD in ESS

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      The units reported by the LabJackAccelerometerDataClient for acceleration PSD are wrong in several ways:

      • ts_config_ocs: the scales need to be inverted. They should be in units of (m/s2)/V rather than V/(m/s2).
      • ts_ess_labjack: the data needs scaling to take into account the sampling rate and possibly the number of datapoints. A discrete Fourier transform (DFT) has the same units as the input. Thus it needs to be scaled by something like the sampling rate to give input units / Hz. Furthermore the 0th element is the sum of all input elements, suggesting that the output of the DFT should be divided by the number of input elements.
      • ts_xml: the claimed units are m2 / (Hz s4). They should be m2 / (Hz2 s4) – Hz needs to be squared.

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            rowen Russell Owen added a comment - - edited

            I also added method psd_from_scaled_data to LabJackAccelerometerDataClient and modified the unit test file for this class to test that method and centralize computation of raw data and predicted PSDs.

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            rowen Russell Owen added a comment - - edited I also added method psd_from_scaled_data to LabJackAccelerometerDataClient and modified the unit test file for this class to test that method and centralize computation of raw data and predicted PSDs. Pull requests: https://github.com/lsst-ts/ts_config_ocs/pull/93 https://github.com/lsst-ts/ts_ess_labjack/pull/16 https://github.com/lsst-ts/ts_xml/pull/602
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            cslage Craig Lage added a comment -

            I have reviewed the code changes and I believe they are correct.

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            cslage Craig Lage added a comment - I have reviewed the code changes and I believe they are correct.
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            rowen Russell Owen added a comment -

            Merged ts_config_ocs and ts_xml to develop.
            Tagged ts_ess_labjack v0.6.4.

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            rowen Russell Owen added a comment - Merged ts_config_ocs and ts_xml to develop. Tagged ts_ess_labjack v0.6.4.

              People

              Assignee:
              rowen Russell Owen
              Reporter:
              rowen Russell Owen
              Reviewers:
              Craig Lage
              Watchers:
              Craig Lage, Patrick Ingraham, Russell Owen
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                Updated:
                Resolved:

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