_transmitter_valid = (tacan != NULL);
if ( _transmitter_valid ) {
SG_LOG( SG_INSTR, SG_DEBUG, "transmitter valid " << _transmitter_valid );
_transmitter_valid = (tacan != NULL);
if ( _transmitter_valid ) {
SG_LOG( SG_INSTR, SG_DEBUG, "transmitter valid " << _transmitter_valid );