SEMTECH-DS is based on several years of intensive development of in-use emission test systems by Sensors’ engineering department, whose expertise in gas analysis stretches over 35 years. All of the technologies were investigated for their accuracy and robustness, two essential requirements for making measurements on vehicles operating under real-world conditions. The final configuration of the instrument represents the best in available technology, comprising a combination of Flame Ionization Detection (FID) with Non-Dispersive InfraRed (NDIR) and Non-Dispersive Ultra Violet (NDUV). These methods provide direct comparison to test cell measurements for THC, CO, CO2, NO and NO2 in compliance with CFR-40, 1065 Subpart J. They provide essential accuracy, resolution and response time while being rugged enough to withstand the shock and vibration encountered in on-board, real-time testing. Using Sensors’ tailpipe exhaust flowmeter and our link to the vehicle’s on-board computer, emission data can be instantaneously measured and presented in g/m (or g/km), g/kg fuel or g/bhp-hr.

Further enhancing the functionality of SEMTECH-DS are optional communications and GPS modules. Data can be provided over cellular or internet links in addition to on-board collection and storage. Location and gradient can also be provided as part of the data file for further processing and analysis.

Today, the SEMTECH-DS was the PEMS system being used to determine measurement allowances, for future in-use compliance testing. Correlation testing at EPA's Ann Arbor laboratory has demonstrated the equivalence of SEMTECH-DS instrumentation with FTP systems (data are available upon request).

SEMTECH-DS' relatively light weight and small size compared to other systems makes it a tremendously adaptable and powerful tool for a variety of purposes. For example, SEMTECH-DS has been used in engine and sub-system development and for on-road fuel economy measurements. Engine performance is carefully monitored through the vehicle interface, while simultaneous emission measurements are captured. Such testing is particularly useful for tracing drivability problems as well as in developing engine and vehicle electronic control strategies.