def init_sdr(self):
        """Initialize SDR

        Do the appropriate action to have a relevant sensor description
        repository for the current management controller
        """
        # For now, return current sdr if it exists and still connected
        # future, check SDR timestamp for continued relevance
        # further future, optionally support a cache directory/file
        # to store cached copies for given device id, product id, mfg id,
        # sdr timestamp, our data version revision, aux firmware revision,
        # and oem defined field
        if self._sdr is None:
            self._sdr = sdr.SDR(self, self._sdrcachedir)
        return self._sdr