# tie filehandle to read/write from serial port (nmea device)
	my $fh = gensym();
	tie( *$fh, 'Device::SerialPort', $config_file )
	  or die("Can't tie $port: $!");
	my $self = bless {
					   PortName              => $port,
					   FileHandle            => $fh,
					   ConfigurationFileName => $config_file
	}, $class;
	$self->{'FileHandle'}->autoflush(1);
	return $self;