| 摘要 |
<p>A system and method for providing navigational direction toward an exit portal or some other point of refuge in an underground mine or other passageway for the benefit of a user carrying a wireless mesh network mobile radio unit. The system provides visual, audible or tactile indication, or a combination of such indications, of navigational direction when beset by emergency conditions including but not limited to reduction of visibility by smoke, airborne particulates such as coal dust or other dust, or fog or other vapor. The system uses properties of data incorporated in digital radio network message packets and measurements of signal strength to determine whether the bearer is moving toward or away from an exit portal or other point of refuge.</p> |
