The EMOxxx  series differential barometer/altimeter (patent pending) environmental monitor is a lower accuracy version of the DBOxxx but provides additional metrics of  humidity and gas.   The EM(BR)xxx, EM(BR)Gxxx and EMDxxx models are ruggedized units integrating this module. 
 
This OEM module provides atmospheric pressures and derived elevations at a rover using corrections transmitted from a stationary base.   In traditional systems elevations are calculated based on pressure readings for a stand-alone unit and are subject to the errors inherent with environmental changes in pressure.  Some applications of this versatile engine include indoor elevations, building pressurization monitoring, multi-node telemetry networks and UAV altitude references.