def init_cal_coeff_dict(obstreemodel):
    """
    Initiate dict for storing meter calibration coefficients.

    Parameters
    ----------
    obstreemodel : ObsTreeModel

    Returns
    -------
    dict
        key: Meter (str), value: float

    """
    try:
        meter_list = {}
        for i in range(obstreemodel.invisibleRootItem().rowCount()):
            survey = obstreemodel.invisibleRootItem().child(i)
            for ii in range(survey.rowCount()):
                loop = survey.child(ii)
                if loop.meter not in meter_list:
                    meter_list[loop.meter] = 1.000
        return meter_list
    except Exception:
        return None