Measuring chain for measuring the noise of road vehicles according to the CPX method
The equipment for measuring according to the CPX method (Close ProXimity Method) is a measuring chain of several devices connected in a system. It consists of a dedicated passenger car with standard tires, 2 microphones, a modular precision sound analyzer, a microphone holder attached to the passenger car and a GPS tracker. The system is designed to measure the rolling noise level of car tires and defines driving surfaces according to the noise they generate. Unlike the SPB method, it enables faster noise evaluation for longer sections.

The measurement method is carried out in accordance with the ISO 11819-2 standard. A dedicated passenger car with standard tires is driven over the test field - typically different road sections. The speed of the car is recorded with a GPS tracker. The modular precision sound analyzer in the car measures the rolling noise of the car tire with two microphones mounted on the microphone holder next to the car wheel. The measuring chain enables the classification of different driving surfaces according to the CPX index, an indicator for the noise level of the driving surface. These data can then be the basis for a model analysis of noise emissions in the vicinity of the considered road sections, or the basis for planning the use of less noisy driving surfaces for the purpose of reducing environmental noise pollution - within the framework of the national operational program for noise protection.