The SEMTECH-DS unit includes a set of gas analyzers, an engine diagnostic scanner, a GPS, an EFM, and embedded software. The gas analyzers measure the concentrations of NOx (NO and NO2), HC, CO, CO2, and oxygen (O2) in the vehicle exhaust. The SEMTECH-DS uses the Garmin International, Inc. GPS receiver model GPS 16 HVS to track the route, elevation, and ground speed of the vehicle on a second-by-second basis.
TTI’s SEMTECH-DS uses the SEMTECH EFM to measure the vehicle exhaust flow. Its post-processor application software uses this exhaust mass flow information to calculate exhaust mass emissions for all measured exhaust gases. The photos to the right show the TTI’s SEMTECH-DS, as well as the EFM installed on a HDDV in a previous test conducted by TTI researchers.