Piana E., Piana G.

The article describes an innovative Pass by system specially developed to fulfil the Standard requirements. It runs on a high flexible platform system, open to the various needs of the NVH field because of its design and software modularity. Differently from other Pass by Systems, is based on a GPS receiver able to track both the vehicle position and its speed twenty times per second. All the test parameters are fully selectable and the driver can interact directly with the application software installed on a small and light PC. Since the system is GPS operating, there is no need to use any radar or light-barrier. The In-Veichle module acts as an interface for the driver and gathers several kinds of data: vehicle position and speed, engine temperature and engine RPM and throttle position. In the meantime the Ground station collects all the information about the acoustical parameters with audio and video stream of the Pass-By test. Bi-directional high transfer rate data connection via Wireless LAN is established between the in-veichle unit and the ground base station, allowing the real time data transfer of the main data. All the information can be displayed both on the pilot screen and, at the same time, on the base station PC. The acoustic mesurements are performed using a multi channel acquisition system. Each channel of the instrument can measures, in parallel and in real-time, SLM values, FFT and 1/3 octave analysis. At the end of the test, the main acoustical data and the GPS quality parameters are shown to the driver that can decide whether to accept or reject the measurement session. The driver can also decide to store the car paths together with the time history and the overall acoustic data of each session for further post processing.